Acinar cell carcinoma of the pancreas metastatic to the ovary: a report of 4 cases

We report 4 cases of acinar cell carcinoma of the pancreas, 3 presenting as metastases in the ovary, the first report of this circumstance, which may pose a broad differential diagnosis and caused significant diagnostic difficulty in all the cases. The average patient age was 57 (range: 28 to 81) years. In 3 cases, the ovarian tumors were detected before the pancreatic tumor; in 1 case, a large abdominal mass and ovarian tumors were discovered synchronously. The ovarian tumors were large, solid, white-tan on gross examination, and bilateral in 3 cases; the single case involving only 1 ovary had 2 discrete masses of tumor. Microscopic examination showed highly cellular neoplasms with a small amount of fibrous stroma. Two cases had a predominant acinar growth pattern of cells with brightly eosinophilic, granular cytoplasm. In 2 cases, the pattern was predominantly solid-cribriform with areas of comedolike necrosis, and the cells had pale eosinophilic, finely granular cytoplasm. Nuclei in all cases were uniform with prominent nucleoli. The main differential diagnostic consideration was well-differentiated neuroendocrine neoplasm (carcinoid tumor); positive immunostaining with antibodies against chymotrypsin and trypsin and negative immunostaining with antibodies against synaptophysin and chromogranin helped exclude this diagnosis. We observed focal alpha-inhibin immunostaining in 2 cases, which may represent a potential diagnostic pitfall, as a Sertoli cell tumor or unusual granulosa cell tumor may also enter the differential diagnosis. Inclusion of antibodies against the pancreatic enzymes chymotrypsin and trypsin in the immunohistochemical panel is critical in establishing the correct diagnosis and should be considered when evaluating ovarian tumors with architectural (mainly acinar) and cytologic (granular eosinophilic cytoplasm) characteristics that should bring a metastatic acinar cell carcinoma into consideration.