Primary pancreatic squamous cell carcinoma with duodenal invasion: Literature review and a case report.

Pancreatic squamous cell carcinoma (PSCC) is a rare pancreatic exocrine tumor. Pancreas does not contain squamous cells, which further makes it a rare tumor. However, several theories have explained histogenesis and mechanism of carcinogenesis. PSCC is very rare, has a poor prognosis and an aggressive nature with limited survival time. We report a 76-year-old African American man with multiple chronic comorbidities who presented with new-onset nausea, vomiting, and abdominal pain. His work-up revealed anemia, and CT scan imaging showed a locally advanced pancreatic body and tail mass with splenic artery encasement and stomach and duodenal obstruction. The tumor caused a mass effect on surrounding structures, namely displacement of the celiac axis, splenic flexure of colon, and distal transverse colon. After discussion with a multidisciplinary hepatopancreaticobiliary tumor board, we elected to proceed for a subtotal pancreatectomy, splenectomy, side to side gastrojejunostomy and a palliative tumor resection. Pathology report confirmed an invasive, moderately differentiated SCC of the pancreas, with direct invasion of duodenum, perineural and lymphovascular invasion, positive peripancreatic soft tissue margin, and 5/24 lymph nodes were positive for metastasis. Immunohistochemistry showed positivity for p40, CK5/6, and CK7, consistent with squamous differentiation. This case aims to shed light on this rare tumor in the differential diagnosis of the pancreatic masses and adds to the growing evidence. It highlights a vigilant clinical evaluation, multidisciplinary approach, and literature review of this rare tumor type.