Schwannomas are benign, slow-growing peripheral nerve sheath tumors commonly occurring in the head, neck, and flexor regions of the extremities. Although most schwannomas are easily diagnosable, their variable morphology can occasionally create difficulty in diagnosis. Reporting pathologists should be aware that schwannomas can exhibit a broad spectrum of morphological patterns. Clinical and radiological examinations can show correlation and should be performed, in conjunction with ancillary tests, when appropriate. Furthermore, deferring a definitive diagnosis until excision may be necessary for small biopsy specimens and frozen sections. This report underscores these challenges through examination of two unique schwannoma cases, one predominantly cellular and the other myxoid, both of which posed significant challenges in histological interpretation.
Background The cytologic diagnosis of poorly differentiated thyroid carcinoma (PDTC) is difficult because it lacks salient cytologic findings and shares cytologic features with more commonly encountered neoplasms. Due to diverse cytologic findings and paucicellularity of PDTC, standardization of cytologic diagnostic criteria is limited. The purpose of this study is to investigate and recognize diverse thyroid findings of fine needle aspiration (FNA) cytology and frozen smear cytology in diagnosis of this rare but aggressive carcinoma.
Methods The present study included six cases of FNA cytology and frozen smears of histologically diagnosed PDTCs.
Results PDTC showed cytologic overlap with well-differentiated thyroid carcinomas (WDTCs). Five of six cases showed dedifferentiation arising from well differentiated thyroid carcinomas. Only one de novo PDTC showed highly cellular smears composed of discohesive small cells, high nuclear/cytoplasmic (N/C) ratio, prominent micronucleoli, and irregular nuclei. Retrospectively reviewed, these findings are highly suspicious for PDTC. Cytologic findings of nuclear atypia, pleomorphism, and irregularity were frequently found, whereas scattered small cells were seen only in the de novo case.
Conclusions Heterogeneous cytologic findings of PDTCs are shared with those of WDTCs and contribute to difficult preoperative cytologic diagnoses. Most PDTCs show dedifferentiation from WDTCs. Albeit rare, de novo PDTC should be considered with cytology showing discohesive small cells with high N/C ratio. This will enable precise diagnosis and prompt treatment of this aggressive malignancy
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J Pathol Transl Med. 2019;53(2):104-111. Published online January 14, 2019
Background Pathologic diagnosis of central nervous system (CNS) neoplasms is made by comparing light microscopic, immunohistochemical, and molecular cytogenetic findings with clinicoradiologic observations. Intraoperative frozen cytology smears can improve the diagnostic accuracy for CNS neoplasms. Here, we evaluate the diagnostic value of cytology in frozen diagnoses of CNS neoplasms.
Methods Cases were selected from patients undergoing both frozen cytology and frozen sections. Diagnostic accuracy was evaluated.
Results Four hundred and fifty-four cases were included in this retrospective single-center review study covering a span of 10 years. Five discrepant cases (1.1%) were found after excluding 53 deferred cases (31 cases of tentative diagnosis, 22 cases of inadequate frozen sampling). A total of 346 cases of complete concordance and 50 cases of partial concordance were classified as not discordant cases in the present study. Diagnostic accuracy of intraoperative frozen diagnosis was 87.2%, and the accuracy was 98.8% after excluding deferred cases. Discrepancies between frozen and permanent diagnoses (n = 5, 1.1%) were found in cases of nonrepresentative sampling (n = 2) and misinterpretation (n = 3). High concordance was observed more frequently in meningeal tumors (97/98, 99%), metastatic brain tumors (51/52, 98.1%), pituitary adenomas (86/89, 96.6%), schwannomas (45/47, 95.8%), high-grade astrocytic tumors (47/58, 81%), low grade astrocytic tumors (10/13, 76.9%), non-neoplastic lesions (23/36, 63.9%), in decreasing frequency.
Conclusions Using intraoperative cytology and frozen sections of CNS tumors is a highly accurate diagnostic ancillary method, providing subtyping of CNS neoplasms, especially in frequently encountered entities.
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Background When differential diagnosis is difficult in thyroid follicular lesions with overlapping histological features, the immunohistochemical staining can help confirm the diagnosis. We aimed to evaluate the effectiveness of rapid immunohistochemical stains of CD56 and cytokeratin 19 on frozen sections of thyroid follicular lesion and explore the possible gains and limitations of the practice. Methods: Eighty-six nodules of 79 patients whose intraoperative frozen sections were selected as the control group, and 53 nodules of 48 patients whose intraoperative frozen sections were subject to rapid immunohistochemistry were selected as the study group. Results: Five nodules (6%) in the control group were diagnosed as follicular neoplasm and six nodules (7%) were deferred. In the study group, six nodules (11%) were follicular neoplasm and none were deferred. Three nodules (4%) in the control group showed diagnostic discrepancy between the frozen and permanent diagnoses, but none in the study group. The average turnaround time for the frozen diagnosis of the control group was 24 minutes, whereas it was 54 minutes for the study group. Conclusions: Intraoperative rapid immunohistochemical stains significantly decreased the diagnostic discrepancy in this study. Considering the adverse effects of indefinite frozen diagnosis or discrepancy with permanent diagnoses, the intraoperative rapid immunohistochemical stain can help to accurately diagnose and hence provide guidance to surgical treatment.
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BACKGROUND Molecular tools for tissue profiling generally require collection of fresh frozen tissues (FFT) as sources of high-quality DNA and RNA. Nowadays, researchers carry out large-scale, multi-center studies and they request inter-institutional minimal intrinsic bias, some fundamental similarities, and the same standardized and validated procedures. METHODS This study reports standardized quality control procedure for fresh frozen tissue of the National Biobank of Korea. RESULTS The main procedures for quality control for FFT are as follows: records related to sample collection such as labeling of samples, transport temperature, lag time from excision of tissue to freezing, and sample size were reviewed for all fresh frozen samples. The stability of RNA and DNA in fresh frozen tissue was evaluated for 3% of collected samples and purity was assessed (ratio of the absorbance at 260 and 280 nm) as was integrity (agarose gel electrophoresis). Stained hematoxylin and eosin sections were reviewed by a pathologist to confirm the diagnosis and to assess how representative the frozen sample was. CONCLUSIONS We introduced that the quality-control criteria for fresh frozen tissue of the NBK. We expect that this study contributes to standardization of collection, storage, and quality control of fresh frozen tissue.
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A retrospective quality assurance study of intraoperative consultation (frozen section) was carried out to assess the accuracy and to determine the reasons of discordance. Of 14,977 surgical pathology cases accessioned over a 6-month period in Asan Medical Center, frozen sections were done on 1,270 (8.5%) patients and 2,392 frozen sections (1.88 frozen sections/case) were performed. Discordance was noted in 106 cases (4.4%) and diagnosis was deferred in 26 cases (1.1%).
All deferred cases were reviewed with the result of 53.8% justified and 46.2% unjustified. The discordant cases were divided into three categories as to their clinical significances: category A (no affect on patient care) 61.3%, B (minimal affect) 9.4%, and C (major affect) 29.2%. Of 31 category C cases, 7 cases were false positive and 24 cases were false negative. Misinterpretation (70.8%) was the leading cause of discordance, followed by sampling error (15.1%), failure to identify lesion (8.5%), and technical problem (5.7%). More than one-third (35.8%) of all discordances were of central nervous system cases. Total central nervous system cases were 403 (16.8%) with a significantly higher disordance rate (9.8%) and deferral rate (2.5%) in comparison to the other cases with 3.4% discordance rate and 0.8% deferral rate. There were 43 colorectal cancer cases of intraoperative consultation for adequacy of resectional margins. The surgical margins were between 0.4 cm and 28 cm (mean: 6.7 cm) away from the tumor and there was no tumor-positive case. The study indicates surgical pathology should 1) promote interpretative skills in cases involving minute fragments of neurosurgical cases, 2) defer the diagnosis and ask for more tissue on inadequate or inappropriate specimens and 3) give only gross opinions without unnecessary frozen section procedures in the event of simple, clear-cut cases.
Quality assurance analysis of frozen section diagnosis is very important for the pathologists to improve the diagnostic ability and the quality of medical service. We analysed 5,273 consecutive cases of frozen section diagnosis which were done in Samsung Medical Center during 10 months from June 1, 1998 to March 31. 1999 with special reference to the discordance between frozen section diagnosis and final diagnosis.
The concordance rate was 97.65%, discordance rate 1.34%, and deferred diagnosis (type 1) rate 1.01%. Category A (discordant diagnosis without any effect on the patients) was 53 cases (1.01%), category B (discordant diagnosis with minimal but no serious effect on the patients) was 10 cases (0.19%), and category C (discordant diagnosis with serious effect on the patients) was 8 cases (0.15%). Type 2 (discordant diagnosis by extra-pathologist problem) was 22 cases (0.42%) and type 3 (discordant diagnosis by pathologist problem) was 49 cases (0.93%). The most frequent causes of type 2 and 3 discordant diagnosis were presence of new lesions on deeper sections and the misinterpretation of lesions. Discordant diagnosis was noted in lymphoreticular system, central nervous system, thyroid, gastric resection margin, breast, female genital organs, intestine, hepatobiliary system, upper aerodigestive tract, urinary tract, lung, and soft tissue in descending order of frequency. Frozen section diagnosis was deferred in central nervous system, lymphoreticular system, gastric resection margin, female genital organs, thyroid, intestine, upper aerodigestive tract, lung, and soft tissue in descending order of frequency. The most important cause of discordant diagnosis was a misinterpretation of the lesions. Based on our results, a continuous and careful follow-up of quality assurance analysis of frozen section diagnosis and a share of experience of problematic cases are mandatory for the pathologists to improve the quality of medical services.
BACKGROUND Core needle biopsy (CNB) is widely used as the initial sampling method for breast cancer. And because frozen section (FS) diagnosis is rapid and reliable, we studied the diagnostic agreement between the diagnosis of FS of CNB and final diagnosis after surgery to evaluate the diagnostic accuracy of the FS of CNB. METHODS Of 409 patients who were preoperatively diagnosed by FS of CNB and who underwent final surgery from 1996 through 2000, 24 cases were found to be ductal carcinoma in situ (DCIS) and 385 cases invasive carcinoma (IC). The diagnoses of FS of CNB were compared with final diagnoses. RESULTS The diagnostic accuracy of carcinoma is 63.6% for DCIS and 86.9% for invasive carcinoma. Five cases (1.2%) could not be diagnosed because of material insufficiency for diagnosis. Twenty two cases (5.4%) were diagnosed as benign on FS, among which 20 (90.9%) were misdiagnosed by sampling error. Twenty seven cases (6.7%) were deferred on FS, 4 of these cases were DCIS, 5 were invasive lobular carcinoma (ILC), the rest displayed low nuclear grades or marked freezing artifacts. CONCLUSIONS The diagnostic accuracy of FS of CNB is very high except for cases of ILC and low grade DCIS. Considering the advantage of rapid evaluation, more definitive diagnosis, familiarity by pathologists and availability of ancillary study, FS of CNB is very useful method as the preoperative evaluation.