Microcystic adenomas (serous cystadenomas) of pancreas. A clinicopathologic investigation of eight cases with immunohistochemical and ultrastructural studies.

Microcystic adenomas are rare tumors, which have only recently been distinguished from other cystic pancreatic lesions. This study details eight cases diagnosed at the Cleveland Clinic. Seven occurred in females. The mean age at diagnosis was 66 years. Abdominal or epigastric pain was the most common symptom. A history of extrapancreatic tumors was frequent, and one patient had a concomitant renal carcinoma with adrenal and renal cysts. The adenomas were multicystic, ranging in size from 2 to 14 cm. Cuboidal epithelial cells with vacuolated or clear cytoplasm containing abundant glycogen lined the cysts. The intervening stromal septa were collagenous and hypocellular. The epithelial cells exhibited strongly positive immunostaining for cytokeratins AE1 and AE3, but did not stain with CEA and Uro-2,3, and 4. Ultrastructurally, the epithelial cells rested on well-formed basal lamina and a delicate subepithelial capillary network. They had blunted apical microvilli and contained glycogen, few lipid droplets, and occasional apical secretory granules. Five adenomas were resected, and three had only a diagnostic biopsy. There were no metastases, but one patient died of postoperative complications following local excision. Elderly or high-risk patients may benefit more from biopsy alone than from attempts at total surgical resection of these benign tumors.