Atypical squamous epithelium in cytologic specimens from the pancreas: Cytological differential diagnosis and clinical implications

Abstract

Atypical squamous epithelium is an uncommon finding in cytologic specimens obtained from pancreatic lesions. A variety of pathologic conditions can result in the presence of these cells, including primary or metastatic carcinomas, chronic pancreatitis, and squamous metaplasia related to pancreatic or biliary duct stent placement. Primary adenosquamous and squamous-cell carcinomas of the pancreas are rare, representing 3.4% and 1.4 % of pancreatic carcinomas, respectively. Cytologic separation of these malignancies from less ominous metaplasias has immense clinical importance. We reviewed Indiana University Hospital's and Duke University's experiences with atypical squamous epithelium occurring within pancreatic aspirates. Study cases were identified using a computer to search the cytology records of these two institutions. Nine cases with a diagnosis of squamous-cell carcinoma, adenosquamous carcinoma, or atypical squamous epithelium were retrieved from the two institutions' Department of Pathology files. One case of pure squamous-cell carcinoma occurred in a patient with a known pulmonary primary; a single case of adenosquamous carcinoma was diagnosed in a patient with a coexistent endometrial primary; a single sample of adenocarcinoma with squamous differentiation was diagnosed in a patient without other known disease; and four primary squamous-cell carcinomas of the pancreas were detected. In addition, a single case of atypical squamous metaplasia associated with a stent was identified, and one case of atypical squamous epithelium associated with chronic pancreatitis was diagnosed. Despite the reactive atypia present in the examples of metaplastic squamous epithelium, separation of these cases from true squamous-cell carcinoma and adenosquamous carcinoma was achievable by cytologic evaluation. No cytologic criteria aided in separating primary pancreatic carcinomas with squamous differentiation from metastatic lesions. In this study, we report our findings in a series of nine cases where cytology disclosed atypical squamous epithelium in the aspirates derived from pancreatic lesions.

The Serine Protease Marapsin Is Expressed in Stratified Squamous Epithelia and Is Up-regulated in the Hyperproliferative Epidermis of Psoriasis and Regenerating Wounds

“…Further analysis of a panel of human pancreatic tissues and pancreatic cell lines confirmed the low expression level in a small number of specimens. Since pancreatic ductal epithelium can undergo squamous metaplasia under pathologic conditions (21,22), it is possible that these pancreas samples had some evidence of this squamous metaplastic change. Although we are unable to reconcile these results with the strong pancreatic marapsin expression observed by Bhagwandin et al (3), our data are very consistent with the stratified squamous epithelium-restricted expression pattern.…”

Primary squamous cell carcinoma of pancreas diagnosed by EUS-FNA: A case report

“…If there is a solid component, it should be targeted during EUS-FNA rather than the cyst. In general, dense orangeophilic keratin debris, atypical parakeratosis, and nuclear atypia including hyperchromasia and nuclear membrane irregularities help us to differentiate cancer from reactive squamous metaplastic cells [24] . A glandular component should also be sought when noting atypical squamous carcinoma cells, as adenosquamous carcinoma is more common than the pure squamous cell type [3] .…”

Squamous Cell Carcinoma of the Pancreas

“…Cubilla and Fitzgerald (as quoted by Layfield et al) in their autopsy study, did not find a primary squamous cell carcinoma of pancreas, but 261 of 411 neoplasms within the pancreas were metastatic, with 49 metastases being from the lung, 12 from the cervix, and 10 from the esophagus 10 . Statistically, the presence of pure squamous cell carcinoma in the pancreas favours a metastatic lesion until proven otherwise, and appropriate radiographic and endoscopic evaluations are needed to rule out this possibility.…”

“…Atypical squamous epithelium can also be seen in cytologic specimens obtained from pancreatic lesions arising from other than inflammatory conditionsfor example, chronic pancreatitis. These conditions may include squamous metaplasia related to pancreatic or biliary duct stent placement, and primary or metastatic squamous cell carcinoma 10 . Differentiation between the atypical squamous epithelium of benign conditions and the cytologic aspirates of carcinoma is possible by noting the small number of atypical cells and the lower degree of nuclear atypia found in the former condition 10 .…”

“…These conditions may include squamous metaplasia related to pancreatic or biliary duct stent placement, and primary or metastatic squamous cell carcinoma 10 . Differentiation between the atypical squamous epithelium of benign conditions and the cytologic aspirates of carcinoma is possible by noting the small number of atypical cells and the lower degree of nuclear atypia found in the former condition 10 . Squamous metaplasia of the pancreatic ducts is found in 9%-64% of pancreases routinely examined at necropsy, and despite the relative frequency of squamous metaplasia, transformation to squamous cell carcinoma of pancreas is an extremely rare occurrence [4][5][6]8 .…”