Journal of Pathology and Translational Medicine

Case Study

Non-keratinizing immature squamous metaplasia in the pancreas mimicking malignancy: a diagnostic pitfall in cytology: Hiroko Hayashi, Tomoaki Kubo, Takuya Hara, Saeko Jinnai, Keisuke Iwasaki; J Pathol Transl Med. 2026;60(4):444-450. Published online July 15, 2026; DOI: https://doi.org/10.4132/jptm.2026.02.19

Abstract PDF: This report describes a challenging case in which atypical immature squamous metaplasia was misinterpreted as malignancy. A 69-year-old man presented with abdominal pain and loss of appetite. Imaging revealed mild pancreatic duct dilation, parenchymal enlargement, and increased fat attenuation in the transverse mesocolon. Endoscopic ultrasound revealed a hypoechoic lesion in the pancreatic body. The serum amylase level was markedly elevated (1,785 U/L), consistent with acute pancreatitis. Repeated pancreatic juice cytology examinations demonstrated atypical epithelial clusters, which raised concerns about possible pancreatic ductal adenocarcinoma. Therefore, distal pancreatectomy with splenectomy and transverse colon resection were performed. However, histopathological examination revealed only atypical immature squamous metaplasia. Retrospective review of the cytological specimens showed overlapping cell clusters with coarse chromatin, prominent nucleoli, nuclear pleomorphism, and peripheral dissociation in a neutrophilic background with focal hemorrhagic necrosis. Although rarely encountered, squamous metaplastic cells can appear in pancreatic cytology and represent a potential pitfall by mimicking adenocarcinoma.

Case Reports

Fine Needle Aspiration Cytology of a Pilomatrixoma Misdiagnosed as Carcinoma: A Case Report.: Ji Han Jung, Young Shin Kim, Kyo Young Lee, Chang Suk Kang, Sang In Shim; J Pathol Transl Med. 1999;10(1):91-96.

Abstract PDF: Sometimes a pilomatrixoma on upper neck can be misdiagnosed as primary salivary gland tumor, skin adnexal tumor or metastatic carcinoma. On fine needle aspiration cytology(FNAC), characteristic features are ghost cells, basaloid cells, and calcium deposits, among which presence of ghost cells seems to be the key to recognize it. Here we present a cytologically misdiagnosed case of pilomatrixoma. A 32-year-old man presented a subcutaneous mass on the right posterior neck. It has grown slowly for 1 year, and was nontender, well circumscribed, hard, and movable mass. An initial FNAC yielded only monomorphic population of highly mitotic basaloid cells, without anucleated ghost cells, chronic inflammatory cells or foreign-body giant cells, suggestive of a poorly differentiated carcinoma. However, that was inconsistent with patient's clinical findings. For further correct diagnosis, FNAC was repeated, which yielded the basaloid cells and foreign-body giant cells. The diagnosis of pilomatrixoma could be made and the mass was excised. This case demonstrates that the pilomatrixoma should be considered in the differential diagnosis of subcutaneous aspirates containing not ghost cells but a dominant population of basaloid cells.

Fine Needle Aspiration Cytology of Inflammatory Pseudotumor of the Lung: Report of A Case Misdiagnosed as Adenocarcinoma .: Wan Seop Kim, Eun Kyung Hong, Moon Hyang Park; J Pathol Transl Med. 1999;10(2):145-149.

Abstract PDF: Cytologic features of inflammatory pseudotumor of the lung have not been described frequently. We report fine needle aspiration cytologic(FNAC) finding of a case of inflammatory pseudotumor misdiagnosed as adenocarcinoma in a 63-year-old man. The FNAC displayed a mixture of histiocytes, myofibroblasts, pneumocytes, and plasma cells. Some histiocytes and myofibroblasts had large nuclei with irregular nuclear membrane and prominent nucleoli, which mislead the diagnosis of adenocarcinoma on FNAC. The heterogeneous cell population is the unique cytologic features of inflammatory pseudotumor, which are helpful to distinguish it from other circumscribed benign and malignant lesions. Familiarity with these features is essential to avoid misdiagnosis and possible overtreatment.

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