Pancreatic-type acinar cell carcinoma of the stomach beneath a focus of pancreatic metaplasia of the gastric mucosa

Summary Acinar cell carcinoma is an uncommon type of carcinoma of the pancreas that can exceptionally arise in ectopic pancreatic tissue. Herein, we report a case of a 52-year-old man with pancreatic-type acinar cell carcinoma of the stomach and concomitant pancreatic metaplasia of the adjacent nonneoplastic gastric mucosa. There was neither clinical nor radiographic evidence of a tumor in the pancreas itself. A subtotal gastrectomy was performed. Macroscopically, an ulcerated tumor, measuring 4 × 1.7 cm, was found in the distal antrum. Microscopically, the biopsy and the surgical specimen revealed a neoplasm with a predominantly trabecular architecture composed of moderately atypical cells with finely dispersed chromatin and indistinct nucleoli. The neoplastic cells and those of the adjacent metaplastic mucosa were both strongly immunoreactive for alpha-1-antitrypsin, consistent with pancreatic acinar cell differentiation. Ectopic pancreatic-type acinar cell carcinoma is an extremely rare condition, having been previously reported only in 5 occasions, none of them in association with pancreatic acinar cell metaplasia of the gastric mucosa.