von Hippel-Lindau disease-associated solid microcystic serous adenomas masquerading as pancreatic neuroendocrine neoplasms.

Background Patients with von Hippel-Lindau disease (VHL) commonly develop pancreatic cysts and neuroendocrine neoplasms (PNENs or PNETs). Solid microcystic serous adenoma (SMSA), a rare neoplasm described in VHL patients, can be mistaken for PNEN on imaging. Methods Clinical, pathologic, and radiologic data were reviewed on VHL patients who underwent surgery for a preoperative diagnosis of PNEN since 1994 at 1 institution. Blinded to the pathologic diagnoses, radiologists reassessed available imaging. Results For 55 patients, 79 pancreatectomies were performed for presumed PNENs. Ten (18%) patients underwent 12 (15%) resections for neoplasms diagnosed as SMSA on final pathology. The average size of a SMSA leading to operation was 3.6 ± 0.4 cm. Four out of 11 SMSAs were still mistaken for PNENs when imaging was reassessed. The mean FDG-positron emission tomography (PET) standardized uptake value was greater for 17 PNENs (12.1 ± 1.2) compared with 6 SMSAs (4.2 ± 0.5; P = .002). The mean doubling time of SMSAs and PNENs was similar. Seven (15%) patients with pathologically proven PNENs had malignant disease. Conclusion SMSAs can mimic PNENs on nonfunctional imaging; FDG-PET may help to differentiate them. A high index of suspicion is needed to minimize operations performed for SMSA and to counsel VHL patients of their risks of undergoing operation for a lesion with no known malignant potential.