Peripancreatic paraganglioma: a potential diagnostic challenge in cytopathology and surgical pathology.

Paragangliomas are rare neuroendocrine neoplasms arising in extra-adrenal chromaffin cells of the autonomic nervous system. In rare instances, paragangliomas present around and involve the pancreas, thereby mimicking one of the more common primary pancreatic lesions. These neoplasms present considerable diagnostic difficulty not only for the clinician and radiologist but also for the pathologist. We have collected a series of 9 peripancreatic paragangliomas clinically simulating a primary pancreatic lesion. The paragangliomas were diagnosed in 4 men and 5 women with an age range of 37 to 78 years (mean, 50 y). Patients presented clinically either with diffuse epigastric and abdominal pain (7 of 9, 78%) or with an incidental mass (2 of 9, 22%) discovered on routine radiographic imaging. All patients were found to have mass lesions suspicious for a primary pancreatic neoplasm on radiographic examination. The lesions were predominantly located in the body of the pancreas (5 of 9, 56%) and ranged in size from 5.5 to 17.0 cm (mean, 10.0 cm). Five of 9 (56%) neoplasms also demonstrated cystic change. Fine-needle aspiration (FNA) was performed on 6 cases; however, the diagnostic accuracy was low, with 3 of 6 (50%) neoplasms misdiagnosed as pancreatic neuroendocrine tumor (PanNET) (n=1), spindle cell neoplasm (n=1), or pseudocyst (n=1). In addition, 2 of 8 (25%) surgically resected tumors were misdiagnosed by the referring pathologist as a PanNET. Immunohistochemistry was performed on all cases, confirming the characteristic 2-cell populations: chief cells (synaptophysin positive and chromogranin A positive) and sustentacular cells (S-100 protein positive). Follow-up information was available for all patients and ranged from 2 months to 11.6 years (mean, 2.7 y). Three of 9 (33%) patients developed metastatic disease, and 2 of these 3 died of their disease at 2.8 and 4.6 years after diagnosis. In summary, in unsuspected cases, interpretation of FNA and surgical pathology resections can be diagnostically challenging. Awareness and proper recognition of this entity, including differential diagnosis, are imperative in establishing the correct diagnosis. Further, close follow-up of these cases should be considered because of the significant risk of metastatic disease.