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A retroperitoneal mass confirmed as a pancreatic adenosquamous carcinoma by endoscopic ultrasound-guided fine-needle aspiration.

Adenosquamous carcinoma is a rare subtype of pancreatic adenocarcinoma, accounting for less than 4% of all exocrine pancreatic malignancies and representing a ductal adenocarcinoma mixed with at least 30% of malignant squamous cells [1–3]. Herein, we report a patient with a retroperitoneal mass in whom endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) and immunohistochemical evaluation confirmed a pancreatic adenosquamous carcinoma (▶Video1). A 65-year-old white man with epigastric pain and weight loss was referred for investigation of a pancreatic mass detected on abdominal computed tomography. Results of clinical laboratory examinations were unremarkable. Sectorial endoscopic ultrasound (Olympus GF-UCT140AL5 [Olympus America Inc., New York, USA], coupled to an ultrasound unit Aloka ProSound alpha-5 SX) detected a solid lesion with irregular borders measuring 4.9 ×3.5 cm in the pancreatic body. EUSFNA was performed via a transgastric approach using a 19-gauge needle (EchoTip Ultra Echo-19; Cook Medical, Winston-Salem, North Carolina, USA) for a total of three passes. There was no on-site cytopathologist. Histopathology on cell blocks demonstrated a mixture of adenocarcinoma cells with malignant squamous epithelium. Immunohistochemistry panel was positive for S100p, cytokeratin 7 (both markers of glandular differentiation), p63, and cytokeratin 5/6 (both markers of squamous epithelium), but negative for chromogranin A andmucin 5AC. Optimal treatment remains undefined for the disease. The patient was offered chemotherapy with gemcitabine. After two cycles, liver metastases were detected. A new chemotherapy protocol was begun with oxaliplatin, folinic acid, and fluorouracil. There was no response and the patient died 6 months later.