Journal of Pathology and Translational Medicine

Original Articles

HER2-low and ultralow breast cancer: interobserver challenges and lessons from a consensus study: Jiwon Koh, Yoon Jin Cha, Eun Yoon Cho, Ahwon Lee, Ja Seung Koo, So Yeon Park, Min Hwan Kim, Jae Ho Jeong, Gyungyub Gong; Received December 17, 2025 Accepted January 8, 2026 Published online March 20, 2026; DOI: https://doi.org/10.4132/jptm.2026.01.08 [Epub ahead of print]

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Abstract PDF: Background
The recent approval of trastuzumab deruxtecan for human epidermal growth factor receptor 2 (HER2)–low and HER2-ultralow breast cancer mandates an adequate assessment of these categories. Methods: Seven breast pathologists from the Breast Pathology Study Group of the Korean Society of Pathologists held an on-site expert consensus meeting. Fifteen sets of virtual whole slide images (WSI) of hematoxylin and eosin stain and HER2 immunohistochemistry were provided. The pathologists were given 60 minutes to submit their diagnosis of HER2 expression into null, ultralow, 1+, 2+, or 3+. Afterwards, in-depth discussion and consensus diagnoses were made by real-time visualization of the WSI. Results: After the consensus meeting, unanimous 100% agreements were seen only in five (33.3%) of the examined cases, which consisted of three 1+ cases and two 2+ cases. Two cases (13.3%) had mild disagreement, with only one pathologist’s disagreement. Of note, eight cases (53.3%) showed significant disagreement, defined by more than two pathologists’ disagreement. All HER2-null cases were reclassified as ultralow after consensus review, suggesting potential widespread underclassification of ultralow cases in clinical practice. Conclusions: Experts had significant discrepancies in interpreting HER2-low/ultralow status. It is important to assess if the distinction between HER2-low and ultralow is strictly required and if HER2-null breast cancer exists in reality.

Progastrin, annexin A2, and tumor-associated macrophages in gastric adenocarcinoma: Konstantinos Christofidis, Rodanthi Fioretzaki, Stylianos Mavropoulos Papoudas, Nikolaos Charalampakis, Nikolaos Kavantzas, Dimitrios Schizas, Stratigoula Sakellariou; J Pathol Transl Med. 2026;60(2):263-279. Published online March 10, 2026; DOI: https://doi.org/10.4132/jptm.2025.12.20

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Abstract PDF Supplementary Material: Background
Gastric adenocarcinoma is a major cause of cancer mortality worldwide, and reliable biomarkers remain insufficient. This study investigates the immunohistochemical expression of progastrin (hPG) and annexin A2 (ANXA2) and the polarization of tumor-associated macrophages in gastric adenocarcinoma to explore their potential prognostic and biological significance. Methods: A retrospective analysis was conducted on formalin-fixed, paraffin-embedded tissue samples from 60 patients with gastric adenocarcinoma (primary tumors, lymph node metastases, and non-tumoral gastric mucosa) and gastric biopsies from 23 healthy controls. The expression of hPG and ANXA2 was quantified using the H-score, and the CD163/human leukocyte antigen–DR (HLA-DR) ratio was used to represent macrophage polarization (M2/M1). Statistical analyses included non-parametric tests, Spearman correlations, Kaplan-Meier survival curves, and Cox proportional-hazards models. Results: ANXA2 expression was significantly elevated in cancer cells from primary tumors and lymph node metastases, compared with the non-tumoral gastric mucosa tissues and gastric mucosa tissues from healthy controls. ANXA2 expression increased with the tumor grade. High ANXA2 levels were associated with shorter overall and disease-free survival, but they did not have independent prognostic value. Although hPG expression correlated positively with ANXA2, it showed no significant prognostic association. The CD163/HLA-DR ratio increased with tumor progression and negatively correlated with ANXA2, but it did not influence survival outcomes. Conclusions: This study is the first to demonstrate the adverse prognostic impact of ANXA2 overexpression in gastric adenocarcinoma tissues from Caucasian patients. Our results suggest that ANXA2 might have utility as a prognostic biomarker and therapeutic target, if further large-scale studies validate and expand our findings.

3-Dimensional reconstruction reveals frequent intraluminal growth of submucosal veins in surgically resected pT1 colorectal cancers: Jihyun Park, Mi-Ju Kim, Yeon Wook Kim, Byong-Wook Lee, Junyoung Shin, Jinho Shin, Chan-Gi Pack, Dong-Hoon Yang, Jihun Kim, In Ja Park, Ralph H. Hruban, Seung-Mo Hong; J Pathol Transl Med. 2026;60(2):246-262. Published online March 10, 2026; DOI: https://doi.org/10.4132/jptm.2025.12.19

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Abstract PDF: Background
Although venous invasion (VI) is associated with distant metastasis and observed in >50% of pT2–4 colorectal cancers (CRCs), the role of VI in pT1 CRCs is not well-defined. Methods: Thirty-four surgically resected pT1 CRCs were reevaluated for 2-dimensional (2D) VI using hematoxylin and eosin (H&E)–stained slides with additional elastic and desmin immunohistochemical staining (cohort A). Additionally, 27 pT1 CRCs without knowing VI status were selected for 3-dimensional (3D) VI evaluation only (cohort B). All 61 cases (cohorts A and B) were studied in 3D using tissue clearing. Results: VI was detected more commonly in 3D (17/34, 50.0%) than in 2D H&E slide evaluation (9/34, 26.5%, p = .047). When VI was identified in 3D (27/61, 44.3%), the most common phase was that of intraluminal growth (22/27, 81.5%), followed by intravasation (7/27, 25.9%) and extravasation (5/27, 18.5%). E-cadherin expression was characterized in 3D in foci of VI and varied in each phase of invasion. Conclusions: All three phases were observed in VI of pT1 CRCs. The extravasation of neoplastic cells from foci of VI in pT1 CRC suggests that VI could be a route of intratumoral spreading in a subset of pT1 CRCs.

Can micro-CT distinguish between solid lung tumors? A comparative evaluation including solid adenocarcinoma, non-keratinizing squamous cell carcinoma, and carcinoid tumor: Selim Sevim, Serpil Dizbay Sak, Kaan Orhan, Arda Buyuksungur, Duru Karasoy, Hilal Ozakinci, Ayten Kayi Cangir; J Pathol Transl Med. 2026;60(2):231-245. Published online March 10, 2026; DOI: https://doi.org/10.4132/jptm.2025.12.16

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Abstract PDF Supplementary Material: Background
Some pulmonary carcinomas display a solid pattern, and immunohistochemistry is commonly used for tumor differentiation. Micro–computed tomography (micro-CT), with its ability to produce detailed three-dimensional images using small voxel sizes, may offer additional insights. This study investigates whether three solid tumor types, solid adenocarcinoma (sAC), non-keratinizing squamous cell carcinoma, and carcinoid tumor (CaT), can be differentiated using micro-CT. Methods: Fifteen paraffin blocks, five for each type, were scanned with micro-CT (Skyscan 1275, Bruker). These images were compared to whole slide images (WSIs) of the same tumors. Consequently, tumoral (n = 74) and non-tumoral (n = 49) regions of interest (tumor ROIs [tROIs] and non-tumor ROIs [ntROIs]) were selected on the micro-CT images and evaluated in terms of certain structural variables (percent object volume, structure model index, structure thickness, structure linear density, connectivity, connectivity density, open porosity, closed porosity) to investigate whether tumors can be differentiated from normal parenchyma and from each other. Results: Although detailed images comparable to WSIs could not be obtained, it was considered an important advantage to be able to examine the entire depth of the paraffin blocks. tROIs and ntROIs could be distinguished based on all variables (p < .001). Additionally, sAC showed a notable difference from CaT in “percent object volume” (p = .011). Conclusions: With ongoing technological advancements, improving image quality without compromising tissue integrity will likely accelerate the adoption of micro-CT in pathology labs. Moreover, structural variables derived from micro-CT images may support differentiation among tumor types.

Correlation between HER2 gene copy number and immunohistochemistry categories in HER2-negative breast cancer: diagnostic utility for differentiating HER2-null, ultralow, and low tumors: Min Chong Kim, Young Kyung Bae; J Pathol Transl Med. 2026;60(2):193-201. Published online February 25, 2026; DOI: https://doi.org/10.4132/jptm.2025.11.07

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Abstract PDF: Background
The recent recognition of human epidermal growth factor receptor 2 (HER2)–low and HER2-ultralow breast cancers (BCs) has expanded the therapeutic relevance of HER2 testing in the antibody-drug conjugate era. However, the biological continuum of HER2 expression measured by immunohistochemistry (IHC) and its relationship with the HER2 gene copy number remain unclear. Methods: We retrospectively analyzed 135 HER2-negative invasive BCs and reclassified them as HER2-null (IHC 0), HER2-ultralow (0+), or HER2-low (1+ or 2+ without amplification). HER2 gene copy number was determined using silver-enhanced in situ hybridization. Statistical analyses were performed to compare HER2 copy number among IHC categories and evaluate the discriminatory value of HER2 copy number for distinguishing IHC subgroups. Results: The mean HER2 copy number increased stepwise across IHC categories: 1.95 ± 0.54 (null), 2.03 ± 0.43 (ultralow), 2.25 ± 0.65 (low, 1+), and 3.29 ± 1.05 (low, 2+). Significant differences were observed between the ultralow and low groups (p = .003) and between the null and low groups (p < .001), but not between the null and ultralow groups or between the ultralow and 1+ groups. Conclusions: HER2 gene copy number was positively correlated with protein expression as reflected by IHC categories. Although HER2 gene copy number was statistically higher in HER2-low than in HER2-null tumors, the substantial overlap in copy number ranges likely limits its utility in distinguishing HER2-low from HER2- null BCs.

Mutational status of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP): molecular analysis should be performed for NIFTPs with nuclear score 3: Ayaka Sako, Mitsuyoshi Hirokawa, Michiko Matsuse, Miyoko Higuchi, Akira Miyauchi, Takashi Akamizu, Atsushi Kawakami, Norisato Mitsutake; J Pathol Transl Med. 2026;60(2):214-219. Published online February 23, 2026; DOI: https://doi.org/10.4132/jptm.2025.12.06

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Abstract PDF: Background
The classification of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was introduced to prevent the overtreatment of indolent tumors that were formerly diagnosed as non-invasive encapsulated follicular variant papillary thyroid carcinomas (NIEFV-PTCs). Although NIFTP was initially estimated to account for 10%–20% of papillary thyroid carcinomas in Western populations, its incidence is substantially lower in Asian cohorts. However, a multi-institutional Japanese study revealed that 31.0% of tumors previously diagnosed as follicular adenomas (FAs) were reclassified as NIFTPs. NIFTP diagnosis requires a nuclear score (NS) of 2–3, and according to the recent World Health Organization criteria, molecular analysis is recommended, but not mandatory, to exclude high-risk subtypes, namely cases with the BRAFV600E mutation, particularly for NS3 tumors. Methods: We performed genetic analysis on 92 archival thyroid tumor samples, including 69 previously diagnosed as FA, of which 34 remained as FA upon re-evaluation (group A) and 35 were reclassified as NIFTP with NS2 (group B). Additional 23 tumors previously diagnosed as NIEFV-PTC were reclassified as NIFTP with NS3 (group C). Results: RAS mutations were detected in 8.8%, 34.3%, and 21.7% of the tumor samples in groups A, B, and C, respectively, whereas BRAF mutations were present in 43.5% of the tumor samples in group C only. Conclusions: These findings suggest the presence of two distinct tumor subsets within NIFTP-NS3, underscoring the need for routine molecular diagnostics in NIFTP-NS3 to facilitate appropriate clinical management.

Multicenter evaluation of the PASS score as a negative predictive tool and the impact of inter-observer variability in pheochromocytoma and paraganglioma risk stratification: Sungyeon Jung, Hye-Ri Shin, Su-Jin Shin, Hee Young Na, Soon-Won Hong, So Yeon Park, Chan Kwon Jung, Kyeong Cheon Jung, Young Lyun Oh, Jae-Kyung Won; J Pathol Transl Med. 2026;60(2):202-213. Published online February 23, 2026; DOI: https://doi.org/10.4132/jptm.2025.11.05

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Abstract PDF: Background
The Pheochromocytoma of the Adrenal Gland Scaled Score (PASS) is widely used for risk stratification in pheochromocytoma and paraganglioma (PPGL), but its clinical utility is limited by inter-observer variability of its parameters and inconsistent predictive performance. Methods: We conducted a multicenter retrospective study of 1,518 patients with PPGL from five tertiary referral centers in Korea. Prognostic utility of PASS system was assessed using logistic regression, Kaplan-Meier analysis, and receiver operating characteristic (ROC) curve analysis. Inter-observer variability was inferred by comparing area under the ROC curve (AUCs) across institutions. Simplified PASS systems were developed based on multivariable analysis of key histopathological parameters. Results: The PASS system was a significant predictor of adverse events and recurrence-free survival. Although the PASS system demonstrated only modest discriminative ability (AUC, 0.673), it showed a high negative predictive value (NPV, 0.885), supporting its usefulness as a screening tool for benign behavior. However, there was significant inter-institutional variability in PASS performance (AUC; range, 0.513 to 0.727; p < .05). The 3-factor Simple PASS, which incorporates necrosis, spindling, and mitotic figures, exhibited less inter-observer variation. The 4-factor Simple PASS, which adds vascular invasion to the 3-factor model, also showed reduced inter-observer variability and improved AUC and NPV compared to the original PASS system. Conclusions: In this multicenter cohort, the PASS system demonstrated high NPV and screening potential, but significant inter-observer variability remains a challenge. Simplification of the PASS system and enhanced pathologist training may improve reproducibility and clinical utility in PPGL risk stratification.

Prevalence of HER2-ultralow breast cancer in South Korea: a multicenter study by reassessment of HER2-zero cases: Min Chong Kim, Eun Yoon Cho, Hee Jin Lee, Ji Shin Lee, Jee Yeon Kim, Wan Seop Kim, Chungyeul Kim, Sun-Young Jun, Hye Jeong Choi, So Mang Lee, Ahrong Kim, Ji-Young Kim, Jeong Yun Shim, Gyungyub Gong, Young Kyung Bae; J Pathol Transl Med. 2026;60(2):184-192. Published online February 23, 2026; DOI: https://doi.org/10.4132/jptm.2025.10.22

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Abstract PDF Supplementary Material: Background
This study aimed to determine the prevalence of human epidermal growth factor receptor 2 (HER2)–ultralow breast cancer among cases initially classified as HER2 immunohistochemistry (IHC) 0 and assess interobserver variability in interpreting low-level HER2 expression. Methods: In this multicenter retrospective study, all invasive breast cancer cases diagnosed between January and December 2022 across 10 Korean institutions were retrieved. Institutional pathologists reexamined HER2 IHC slides originally reported as IHC 0 according to the 2018 American Society of Clinical Oncology/College of American Pathologists guidelines and reclassified them as HER2-null (0), HER2-ultralow (0+), or HER2-low (1+). Slides from 10% of HER2-null and HER2-ultralow cases were digitized for central review and independently assessed by two pathologists, with discrepancies resolved by consensus. Results: Among 8,026 cases, 2,836 cases (35.5%) were initially reported as IHC 0. Upon re-review, 1,673 (59.0%), 1,139 (40.2%), and 24 (0.8%) cases were reclassified as HER2-null, HER2-ultralow, and HER2-low, respectively. The prevalence of HER2-ultralow breast cancer varied considerably across institutions (23.7%–78.1%). Central review of 268 digitized cases showed concordance in 193 cases (72.0%). Among the 75 discordant cases, 54 tumors (72.0%) were upgraded from HER2-null to HER2-ultralow, and 18 (24.0%) tumors were upgraded from HER2-ultralow to HER2-low. Furthermore, two tumors (2.7%) were downgraded from HER2-ultralow to HER2-null. Conclusions: Approximately 40% of cases initially categorized as IHC 0 were reclassified as HER2-ultralow. The substantial inter-institutional variability observed in interpreting low-level HER2 expression highlights the need for standardized training and quality assurance to ensure accurate identification of patients eligible for HER2-targeted antibody–drug conjugates.

Significance of KM55 immunohistochemical staining in the diagnosis and prognosis of IgA nephropathy: Hoe In Jeong, Beom Jin Lim, Minsun Jung; J Pathol Transl Med. 2026;60(1):69-82. Published online January 14, 2026; DOI: https://doi.org/10.4132/jptm.2025.09.17

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Abstract PDF: Background
Galactose-deficient IgA1 (Gd-IgA1) plays a crucial role in IgA nephropathy (IgAN). The monoclonal antibody KM55 has emerged as a simplified method for detecting Gd-IgA1; however, the clinicopathological significance of immunohistochemistry for Gd-IgA1 remains underexplored. This study evaluated the prognostic and clinicopathological significance of KM55 immunohistochemistry in IgAN. Methods: A total of 114 native kidney biopsies showing at least mild mesangial IgA positivity on immunofluorescence were retrospectively analyzed. Patients were categorized as having IgAN or non-IgAN diseases. The KM55 immunohistochemical staining was graded as 0, 1+, 2+, 3, or 4+. Data on Oxford classification, laboratory parameters, and renal outcomes were collected. Results: The IgAN group showed significantly higher KM55 scores than the non-IgAN group (median: 3 vs. 1; p < .001). IgAN cases were further stratified into KM55-high (≥3+, n = 38) and -low groups (≤2+, n = 37). The KM55-high group had significantly higher diastolic blood pressure, blood urea nitrogen, creatinine, urine protein/creatinine ratio, and Oxford mesangial hypercellularity scores, along with lower estimated glomerular filtration rate (eGFR) and serum albumin. Cox analysis revealed significantly poorer outcomes in the KM55-high group for chronic kidney disease stage 4 (p = .015), end-stage renal disease (p = .024), and 75% eGFR decline (p = .016). Conclusions: Mesangial Gd-IgA1 deposition graded by KM55 immunohistochemistry may be a useful adjunct for IgAN diagnosis and a potential prognostic biomarker.

The significance of papillary architecture in the follow-up biopsies of patients with progestin-treated atypical endometrial hyperplasia: Wangpan J. Shi, Oluwole Fadare; J Pathol Transl Med. 2026;60(1):58-68. Published online January 8, 2026; DOI: https://doi.org/10.4132/jptm.2025.09.12

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Abstract PDF: Background
Follow-up biopsies in patients with progestin-treated atypical endometrial hyperplasia/endometrioid intraepithelial neoplasia (AH/EIN) may show papillary structures, the significance of which is unclear. Methods: The authors reviewed 253 serial specimens of 84 consecutive patients diagnosed with AH/EIN, inclusive of each patient's pre-progestin treatment sample and all post-treatment specimens. We assessed the predictive relationship between papillary architecture in a post-treatment biopsy and two study outcomes: AH/EIN or carcinoma in at least one sample subsequent to the one in which papillae were identified, and/or the last specimen received for that patient. Results: Papillae were identified in only 51.5% of pre-treatment samples but were present in at least one subsequent post-treatment sample for all patients. Post-treatment samples that exhibited papillae and no glandular crowding were associated with AH/EIN in at least one subsequent specimen in 39.7% (29/73) of cases, compared to 24.0% (6/25) in samples with neither papillae nor glandular crowding (p = .227) and 64.0% (16/25) in samples with concurrent gland crowding and papillae (p = .048). Univariate logistic regression analyses showed that the presence of papillae was not associated with study outcomes (odds ratio [OR], 0.99; 95% confidence interval [CI], 0.49 to 1.99; p = .985), as compared with gland crowding (OR, 1.54; 95% CI, 1.04 to 2.27; p = .031), or concurrent papillae and gland crowding (OR, 2.36; 95% CI, 1.01 to 5.52; p = .048). Conclusions: In post-treatment samples of progestin-treated AH/EIN, the presence of papillary architecture was not demonstrably associated with study outcomes independent of gland crowding, although the concurrent presence of both features may be significantly predictive.

Review Article

Solitary fibrous tumor: an updated review: Joon Hyuk Choi; J Pathol Transl Med. 2026;60(1):20-46. Published online December 29, 2025; DOI: https://doi.org/10.4132/jptm.2025.10.08

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Abstract PDF: Solitary fibrous tumor (SFT) is a fibroblastic neoplasm characterized by a branching, thin-walled dilated staghorn-shaped (hemangiopericytoma-like) vasculature and a NAB2::STAT6 gene fusion. SFTs can occur in almost any anatomical location, including superficial and deep soft tissues, visceral organs, and bone. They most commonly occur in extrapleural locations, equally affect both sexes, and are typically present in adults. Although metastasis is rare, SFTs frequently show local recurrence. The diagnosis of SFTs is difficult because of their broad histological and morphological overlap with other neoplasms. An accurate diagnosis is important for guiding disease management and prognosis. Despite advances in molecular diagnostics and therapeutic strategies, the biological complexity and unpredictable clinical behavior of SFTs present significant challenges. This review provides an updated overview of SFT, with a focus on its molecular genetics, histopathological features, and diagnostic considerations.

Original Articles

Diagnostic value of cytology in detecting human papillomavirus–independent cervical malignancies: a nation-wide study in Korea: Hye-Ra Jung, Junyoung Shin, Chong Woo Yoo, Eun Na Kim, Cheol Lee, Kyeongmin Kim, Ho-chang Lee, Yonghee Lee, Ji Hye Kim, Soo Jin Jung, Yumin Chung, Joo Yeon Kim, Hye Eun Park, Tae Hoen Kim, Wonae Lee, Min-Sun Cho, Ran Hong, Yoon Jung Choi, Younghee Choi, Young Sub Lee, Sang-Ryung Lee, Myunghee Kang, Young Jin Seo, Seung-Sook Lee, Yoon-Jung Hwang, Hyun-Jung Kim; J Pathol Transl Med. 2025;59(6):444-452. Published online November 11, 2025; DOI: https://doi.org/10.4132/jptm.2025.10.21

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Abstract PDF: Background
Human papillomavirus (HPV) independent cervical malignancies (HPV-IDCMs) have recently been classified by the World Health Organization (WHO) 5th edition. These malignancies have historically received limited attention due to their rarity and the potential for evasion of HPV-based screening.
Methods
We retrospectively reviewed 5,854 biopsy-confirmed cervical malignancies from 22 institutions over 3 years (July 2020–June 2023). Histologic classification followed the WHO guidelines. HPV independence was confirmed by dual negativity for p16 and HPV; discordant cases (p16-positive/HPV-negative) underwent additional HPV testing using paraffin-embedded tissue. Cytological results were matched sequentially to histological confirmation.
Results
The prevalence of HPV-IDCM was 4.4% (257/5,854) overall and was 3.6% (208/5,805 cases) among primary cervical malignancy. Patient age of HPV-IDCM was 29 to 89 years (median, 57.79). Its histologic subtypes included primary adenocarcinoma (n = 116), endometrial adenocarcinoma (n = 35), squamous cell carcinoma (n = 72), metastatic carcinoma (n = 14), carcinoma, not otherwise specified (n = 10), neuroendocrine carcinoma (n = 3), and others (n = 7). Among 155 cytology-histological matched cases, the overall and primary Pap test detection rates were 85.2% (132/155) and 83.2% (104/125), respectively. The interval between cytology and histologic confirmation extended up to 38 months.
Conclusions
HPV-IDCMs comprised 3.6% of primary cervical malignancies with a high detection rate via cytology (83.2%). These findings affirm the value of cytological screening, particularly in patients with limited screening history or at risk for HPV-independent lesions, and may guide future screening protocols.

E-cadherin expression and tumor-stroma ratio as prognostic biomarkers of peritoneal recurrence in advanced gastric cancer: a digital image analysis-based stratification study: Somang Lee, Binnari Kim; J Pathol Transl Med. 2025;59(6):408-420. Published online November 6, 2025; DOI: https://doi.org/10.4132/jptm.2025.08.27

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Abstract PDF: Background
Gastric cancer remains a significant global health burden, with a high peritoneal recurrence rates after curative surgery. E-cadherin and the tumor-stroma ratio (TSR) have been proposed as prognostic indicators, but their combined prognostic utility remains unclear. Methods: This retrospective study included 130 patients with T3/T4a gastric cancer who underwent curative gastrectomy at Ulsan University Hospital between 2014 and 2019. Immunohistochemistry for E-cadherin and Vimentin was performed. Digital image analysis using QuPath’s object classifier quantified E-cadherin expression and TSR. Results: Low E-cadherin expression was associated with diffuse-type histology and advanced T stage. Low TSR was linked to younger age, female sex, and XELOX treatment. In Kaplan-Meier analysis, low TSR showed a non-significant trend toward higher peritoneal recurrence (p = .054), while low E-cadherin expression was significantly associated with increased peritoneal recurrence (p = .002). Combined biomarker analysis also revealed a significant difference in recurrence-free survival (RFS) among the four groups (p = .005); patients with both high TSR and high E-cadherin expression experienced the most favorable RFS. In multivariable analysis, E-cadherin expression remained the only independent predictor of peritoneal recurrence (high vs. low; hazard ratio, 0.348; 95% confidence interval, 0.149 to 0.816; p = .015). Conclusions: E-cadherin and TSR reflect distinct tumor biology such as epithelial integrity and stromal composition, and their combined evaluation improves prognostic stratification. Digital image analysis enhances reproducibility and objectivity, supporting their integration into clinical workflows.

Spectrum of thyroiditis types: clinical, cytomorphological, and radiological findings: Anam Singh, Indrajeet Kundu; J Pathol Transl Med. 2025;59(6):421-433. Published online November 6, 2025; DOI: https://doi.org/10.4132/jptm.2025.08.13

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Abstract PDF: Background
Thyroiditis encompasses a range of inflammatory conditions affecting the thyroid gland. Lymphocytic thyroiditis (LT) is a common form of thyroiditis, with acute suppuration of the thyroid, while tuberculous thyroiditis is relatively rare. Fine-needle aspiration cytology (FNAC) remains a safe and cost-effective tool for diagnosing thyroid-related diseases, especially when paired with ultrasound (US) and clinical examination. Methods: This is a cross-sectional study including 21 cases. The cases were reported as thyroiditis on US and FNAC, and the findings were correlated with patient clinical history, symptoms during presentation, and serological profiles. Results: The cases of thyroiditis encompassed the more common forms, LT and subacute granulomatous thyroiditis (SAT), as well as relatively rare forms like tuberculous thyroiditis and thyroid abscess. Cases of follicular neoplasms (FN) arising in the context of LT also are included in this study. The case of tuberculous thyroiditis presented as a bulky thyroid gland that appeared heterogeneous on US with extensive necrosis on FNAC. The cases of thyroid abscess and SAT presented with painful neck swellings, with granulomas in the latter cases. US features of LT showed an array of appearances ranging from pseudonodular to an atrophic thyroid gland. All cases of FN showed a lymphocytic background. Conclusions: Thyroiditis is a commonly encountered condition that needs to be sub-categorized accurately into acute, subacute, and chronic types for appropriate clinical management, as they can sometimes show overlapping features. Though rare, acute suppurative and tuberculous thyroiditis are often encountered and warrant immediate care and treatment.

Review Article

Breast schwannoma: review of entity and differential diagnosis: Sandra Ixchel Sanchez, Ashley Cimino-Mathews; J Pathol Transl Med. 2025;59(6):353-360. Published online November 3, 2025; DOI: https://doi.org/10.4132/jptm.2025.08.12

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Abstract PDF: Schwannomas are benign peripheral nerve sheath tumors composed of Schwann cells, which uncommonly involve the breast. Most breast schwannomas are clinically present as a superficial palpable breast mass but may also be detected on screening mammography. Excision is the preferred treatment if symptomatic, and these are not known to recur. Histomorphology is similar to other anatomic sites: bland spindle cells with wavy nuclei, nuclear palisading (Verocay bodies), variably hypercellular (Antoni A) and hypocellular (Antoni B) areas, myxoid stroma, hyalinized vessels and variable cystic degeneration. Classic immunohistochemistry is diffuse and strong labeling for S100 and Sox10. Notable diagnostic pitfalls specific to the breast include myofibroblastoma, particularly the palisaded variant, and fascicular pseudoangiomatous stromal hyperplasia.

Case Study

Clinicopathological characteristics of digestive system angioleiomyomas: case report and literature review: Georgios Kalliopitsas, Christos Topalidis, Constantine Halkias, Theodora Gkeka, Konstantinos Sapalidis, Triantafyllia Koletsa; J Pathol Transl Med. 2025;59(6):453-459. Published online October 28, 2025; DOI: https://doi.org/10.4132/jptm.2025.08.04

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Abstract PDF: Angioleiomyomas are benign soft tissue tumors originating from the vascular wall. Although angioleiomyomas mainly occur in extremities, followed by head, neck, and trunk, they can also be found throughout the digestive system and especially in the oral cavity. Herein, the fourth case of a rectal angioleiomyoma in the English literature is reported and the clinicopathological features of digestive system angioleiomyomas were investigated. In contrast to their soft tissue counterparts, digestive system angioleiomyomas mainly affect males at a slightly younger age. Angioleiomyomas are mainly asymptomatic and only rarely elicit pain. Clinicians consider angioleiomyomas infrequently and instead include more common soft tissue or epithelial tumors in their differential diagnosis. To prevent angiomyolipoma misdiagnosis, pathologists should exercise caution when examining an angioleiomyoma composed of adipose tissue, smooth muscle, and blood vessels. Pathologists, radiologists, and surgeons should be aware that angioleiomyomas can occur in the digestive system.

Original Article

Clinicopathological implications of miR-3127 in melanoma: Truong Phan-Xuan Nguyen, Minh-Khang Le, Chau M. Bui, Vuong Gia Huy; J Pathol Transl Med. 2025;59(6):371-381. Published online October 16, 2025; DOI: https://doi.org/10.4132/jptm.2025.07.08

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Abstract PDF Supplementary Material: Background
Cutaneous melanoma is the most lethal of all skin cancers. Recent studies suggested that miR-3127 is dysregulated in multiple tumor types and has important roles in tumorigenesis and cancer progression, giving it potential as a prognostic biomarker. The aim of this study was to use bioinformatic analysis to assess miR-3127 expression and correlate expression patterns with disease course in patients with cutaneous melanoma. Methods: miRNA, mRNA sequencing, DNA methylation data, and clinical information of cutaneous melanoma cases were downloaded from the Human Cancer Atlas – Skin Cutaneous Melanoma (TCGA-SKCM). miR-3127 expression was classified into miR-3127–low and miR-3127–high clusters using maximally selected rank statistics. Results: Clustering analysis showed that high expression of miR-3127 (≥20.3 reads per million) was associated with worse progression-free (p < .001) and overall (p = .011) survival compared to low miR-3127 expression. More than five thousand differentially expressed genes between the two miR-3127 sample groups encoded cell differentiation markers, cytokines, growth factors, translocated cancer genes, and oncogenes. Pathway analysis revealed that miR-3127–high samples related to activity of proliferation, DNA repair, and ultraviolet response. Conclusions: The expression level of miR-3127 could act as a prognostic indicator for patients with melanoma.

Case Study

Cytological characteristics of Müllerian adenosarcoma of the uterine corpus: a case report and literature review: Junko Kuramoto, Chihiro Matsubara, Yasuko Sasamoto, Hitomi Tsukada, Shigemichi Hirose; J Pathol Transl Med. 2025;59(5):340-347. Published online September 11, 2025; DOI: https://doi.org/10.4132/jptm.2025.08.11

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Abstract PDF: Müllerian adenosarcoma of the uterus is a rare morphological variant of uterine sarcoma. Müllerian adenosarcoma has been described histologically, though it is rare in the cytological literature. This report describes the cytological findings of a case of adenosarcoma arising from the endometrium. The patient was a Japanese woman in her 40s. Endometrial cytological and histological findings were observed for 5 years, from the appearance of a polypoid lesion until adenosarcoma was suspected, and then hysterectomy was performed. Based on these longitudinal cytological and histological observations, it was possible to identify the cytological characteristics of adenosarcoma: decrease in the glandular-to-stromal ratio; increase in stromal cell density; and progression of stromal cell atypia. This case stresses the importance and usefulness of endometrial cytology in the identification of the sarcomatous component in adenosarcoma.

Original Articles

Characterization of undifferentiated carcinoma of the salivary gland: clinicopathological and immunohistochemical analyses in comparison with lymphoepithelial carcinoma: Sangjoon Choi, Gyuheon Choi, Hee Jin Lee, Joon Seon Song, Yoon Se Lee, Seung-Ho Choi, Kyung-Ja Cho; J Pathol Transl Med. 2025;59(6):361-370. Published online September 8, 2025; DOI: https://doi.org/10.4132/jptm.2025.07.07

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Abstract PDF: Background
This study aimed to reclassify a subset of poorly differentiated salivary gland carcinoma that do not conform to any entities of the current World Health Organization (WHO) classification into the category of undifferentiated carcinoma (UDC) because they lack specific histologic differentiation or immunophenotype. Methods: Cases of salivary gland carcinomas from Asan Medical Center (2002–2020) that did not fit any existing WHO classification criteria and were diagnosed as poorly differentiated carcinoma, high-grade carcinoma, or UDC, were retrospectively reviewed. Immunohistochemical (IHC) staining for p40, neuroendocrine markers, androgen receptor (AR), and gross cystic disease fluid protein 15 (GCDFP-15) and Epstein-Barr virus (EBV) in situ hybridization (ISH) were performed. Clinical data were collected from the electronic medical records. Results: Six salivary gland carcinomas did not align with any specific entities and lacked distinct differentiation. Two of six cases displayed lymphoepithelial carcinoma (LEC)-like morphology but were negative or showed negligible immunoreactivity for p40 and EBV ISH, distinguishing them from LEC of the salivary gland. Two cases showed strong AR positivity, suggesting a potential overlap with salivary duct carcinoma (SDC) but lacked classic SDC morphologies and GCDFP-15 expression. No cases expressed neuroendocrine markers. Conclusions: This study proposes reclassifying these poorly differentiated or high-grade salivary gland carcinomas as UDC based on their indeterminate differentiation and IHC profiles. This may lead to a clearer diagnostic category and enhance our understanding of these high-grade tumors.

Evaluation of potential prognostic significance of JUNB in human prostate cancer: a bioinformatic and histopathological study: Noha R. Noufal, Einas M. Yousef, Mohamed Taha; J Pathol Transl Med. 2025;59(5):291-305. Published online September 8, 2025; DOI: https://doi.org/10.4132/jptm.2025.06.06

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Abstract PDF Supplementary Material: Background
Prostate cancer is one of the most common malignancies in males worldwide. Serum prostate-specific antigen is a frequently employed biomarker in the diagnosis and risk stratification of prostate cancer; however, it is known for its low predictive accuracy for disease progression. New prognostic biomarkers are needed to distinguish aggressive prostate cancer from low-risk disease. This study aimed to identify and validate potential prognostic biomarkers of prostate cancer. Methods: Two prostate cancer datasets from the Gene Expression Omnibus were analyzed to identify differentially expressed genes between benign prostatic hyperplasia (BPH) and prostatic carcinoma. Immunohistochemistry was used to evaluate the JUNB proto-oncogene, a subunit of the AP-1 transcription factor (JUNB), in 70 prostate cancer patients and 10 BPH samples. Results: Our findings showed that JUNB was significantly enriched in prostate cancer-related pathways and biological processes. JUNB expression was considerably higher in prostatic adenocarcinoma patients than in BPH patients. Regarding JUNB expression in prostate cancer cases, lower levels of JUNB expression were associated with higher grades of prostatic adenocarcinoma. Lower JUNB expression was associated with a higher risk of prostatic adenocarcinoma progression and shorter overall survival. Conclusions: These results suggest that JUNB is a promising prognostic biomarker and a potential tumor suppressor in prostate cancer.

Review Article

Central nervous system tumors with BCOR internal tandem duplications: a systematic review of clinical, radiological, and pathological features in 69 cases: Ji Young Lee, Sung Sun Kim, Hee Jo Baek, Tae-Young Jung, Kyung-Sub Moon, Jae-Hyuk Lee, Kyung-Hwa Lee; J Pathol Transl Med. 2025;59(5):273-280. Published online September 1, 2025; DOI: https://doi.org/10.4132/jptm.2025.07.23

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Abstract PDF Supplementary Material: Central nervous system tumors with BCL6 corepressor (BCOR) internal tandem duplications (ITDs) constitute a rare, recently characterized pediatric neoplasm with distinct molecular and histopathological features. To date, 69 cases have been documented in the literature, including our institutional case. These neoplasms predominantly occur in young children, with the cerebellum representing the most frequent anatomical location. Radiologically, these tumors present as large, well-circumscribed masses frequently demonstrating necrosis, hemorrhage, and heterogeneous enhancement. Histologically, they are characterized by a monomorphic cellular population featuring ependymoma-like perivascular pseudorosettes, myxoid stroma, and elevated mitotic activity. Immunohistochemically, these tumors exhibit sparse glial fibrillary acidic protein expression while consistently demonstrating positive staining for vimentin and CD56. The defining molecular hallmark is a heterozygous ITD within exon 15 of the BCOR gene, with insertions ranging from 9 to 42 amino acids in length. BCOR immunohistochemistry reveals nuclear positivity in 97.9% of examined cases, although this finding is not pathognomonic for BCOR ITDs. This comprehensive review synthesizes data from all published cases of this novel tumor entity, providing a detailed analysis of clinical presentation, neuroimaging findings, histopathological features with differential diagnostic considerations, therapeutic approaches, and prognostic outcomes.

Original Article

AMACR is a highly sensitive and specific immunohistochemical marker for diagnosing prostate cancer on biopsy: a systematic review and meta-analysis: Johannes Cansius Prihadi, Stevan Kristian Lionardi, Nicolas Daniel Widjanarko, Steven Alvianto, Fransiskus Xaverius Rinaldi, Archie Fontana Iskandar; J Pathol Transl Med. 2025;59(4):235-248. Published online July 3, 2025; DOI: https://doi.org/10.4132/jptm.2025.04.16

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Abstract PDF Supplementary Material

Background
Alpha-methylacyl-CoA racemase (AMACR) is the preferred biomarker for distinguishing malignant from benign glands in prostate biopsies, showing high sensitivity and specificity for prostate cancer. A meta-analysis of immunohistochemistry (IHC) for AMACR is essential to further assess its diagnostic accuracy across diverse sample sources. Methods: A systematic search of databases including MEDLINE, ScienceDirect, ProQuest, Google Scholar, and the Cochrane Library was performed, focusing on studies of AMACR to diagnose prostate cancer, particularly in biopsy samples analyzed through IHC over the last 20 years. Quality of studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 tool, followed by a meta-analysis of regions and subgroups to calculate summary estimates of diagnostic test accuracy. Results: In the final analysis, 37 studies, with a pooled size of 5,898 samples, were included from the examination of 94 full-text papers. Among them, 27 studies with similar sample sources and testing methodologies underwent meta-analysis, yielding a combined sensitivity estimate of 0.90 (95% confidence interval [CI], 0.86 to 0.93) and specificity of 0.91 (95% CI, 0.83 to 0.95), both with significant heterogeneity (p < .01). The region beneath the hierarchical summary receiver operating characteristic curve was 0.95 (95% CI, 0.93 to 0.97), positive likelihood ratio was 9.6 (95% CI, 5.3 to 17.4), negative likelihood ratio was 0.11 (95% CI, 0.08 to 0.15), and diagnostic odds ratio was 88 (95% CI, 42 to 181). Conclusions: Our meta-analysis findings substantiate AMACR as a highly accurate tool for diagnosing prostate cancer, specifically in biopsy samples, via immunohistochemical staining. Further studies involving diverse samples are needed to enhance our understanding of the AMACR diagnostic accuracy in a range of clinical settings.

Citations

Citations to this article as recorded by

Pathogenesis-Guided Biomarker Assessment: A Shift in Prostate Cancer Diagnostics
Jessica M. Logan, Victoria Malone, John J. O’Leary, Doug A. Brooks
International Journal of Molecular Sciences.2025; 26(24): 11786. CrossRef

Case Studies

Acquired aberrant partial CD3 expression in recurrent Epstein-Barr virus–negative solitary plasmacytoma of tonsil: Chenchen Niu, Dong Ren, Truc Tran, Ashley Gamayo, Sherif Rezk, Xiaohui Zhao; J Pathol Transl Med. 2025;59(4):262-268. Published online May 15, 2025; DOI: https://doi.org/10.4132/jptm.2025.04.17

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Abstract PDF: The aberrant expression of specific T-cell maker CD3 in B-cell neoplasms can be a potential diagnostic pitfall leading to a misclassification of cell lineage. Here, we report a case of recurrent solitary plasmacytoma with new aberrant expression of CD3. The neoplastic plasma cells of the recurrent tumor were kappa restricted, positive for CD138, MUM1, negative for CD20, cyclin D1, and Epstein-Barr virus. CD79a was positive in majority of the tumor cells, except for a small focus which was strongly positive for CD3, but negative for other T-cell markers (CD2, CD5, CD7, CD4, and CD8) and CD56. The neoplastic plasma cells of the original tumor were negative for CD3. To the best of our knowledge, only one case of recurrent plasmacytoma with aberrant expression of CD3 has been published, which revealed disease progression in the recurrence. However, we did not observe morphologic evidence of disease progression in our case.

Cytological features of atypical adenomatous hyperplasia and adenocarcinoma in situ of the lung: a case report: Misa Takahashi, Seiya Homma, Chisato Setoguchi, Yoko Umezawa, Atsuhiko Sakamoto; J Pathol Transl Med. 2025;59(3):195-200. Published online May 9, 2025; DOI: https://doi.org/10.4132/jptm.2025.04.09

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Abstract PDF: Atypical adenomatous hyperplasia (AAH) and adenocarcinoma in situ (AIS) are generally treated as different lesions, depending on the differences in lesion size and histological findings. However, these differences are not absolute; thus, AAH and AIS are often difficult to distinguish. Moreover, whether AAH and AIS can be regarded as different lesions remains unknown because cytological specimens, especially those of AAH, are rare. In this study, we examined these uncommon cytological specimens and compared the cytological findings between AAH and AIS. We observed many common cytological features with no obvious differences between AAH and AIS. These findings suggest that these two distinct lesions can be grouped into a single category. Therefore, we propose creating a new cytological category.

Original Articles

Primary Merkel cell carcinoma of the salivary gland: a clinicopathologic study of four cases with a review of literature: Gyuheon Choi, Joon Seon Song, Hee Jin Lee, Gi Hwan Kim, Young Ho Jung, Yoon Se Lee, Kyung-Ja Cho; J Pathol Transl Med. 2025;59(3):171-179. Published online April 30, 2025; DOI: https://doi.org/10.4132/jptm.2025.03.25

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