A Case of Primary Squamous Cell Carcinoma of the Duodenum Definitively Diagnosed by p16 Immunostaining

Abstract

A patient with primary squamous cell carcinoma of the duodenum that was definitively diagnosed by p16 immunostaining is reported. An 81-year-old woman underwent plain chest computed tomography (CT) during a regular examination in which a tumor of the descending part of the duodenum was identified incidentally. Upper gastrointestinal endoscopy showed signs suggestive of Type 2 advanced carcinoma. Biopsies were taken from four sites in the lesion, all of which contained squamous cell carcinoma with invasive proliferation of keratinized cells. Since contrast-enhanced CT and positron emission tomography-CT did not show any obvious distant metastasis, pancreaticoduodenectomy was performed. Due to its morphology, the possibility of squamous cell carcinoma of the pancreas was also suggested during pathological testing, but p16 immunostaining demonstrated that it was actually primary squamous cell carcinoma of the duodenum.

Primary squamous cell carcinoma of the duodenum is a rare condition. Immunostaining is useful for definitive diagnosis, and this may be helpful for diagnosis of future cases.