Paraganglia of the Gallbladder: An Underrecognized Incidental Finding and Potential Diagnostic Pitfall.

The identification of paraganglia (PG) in the gallbladder (GB) is infrequent, and easily overlooked as it is not something routinely reported. Occasionally they may be misinterpreted as neoplastic cells, such as low-grade carcinomas, germ cell tumors, or because of their close resemblance to neuroendocrine cells, as low-grade neuroendocrine neoplasms. To evaluate the incidence and histological features of PG of the GB in patients that underwent cholecystectomy, and discuss the potential misinterpretation of these benign structures as clusters of neoplastic cells. A retrospective study of cholecystectomy specimens performed during a 6-month period were reviewed for identification of PG. Immunohistochemical studies for chromogranin, synaptophysin, S100, and cytokeratin AE1/AE3 were performed in selected cases. A total of 365 GBs were reviewed and in 16 cases (4.4%) PG was identified within the subserosal connective tissue of the GB wall or cystic duct adjacent to small capillaries, nerves, and ganglia. They consisted of well-demarcated, lobular structures ranging in size from 0.2 to 0.5 cm, which were predominantly composed of chief cells, with strong expression for chromogranin and synaptophysin and negative CKAE1/AE3, and a minor component of S100-positive sustentacular cells. PG is an uncommon finding with a prevalence of 4.4% in our study. Awareness of their location, histologic features, and immunohistochemical profile may help practicing pathologists to confirm their benign nature, avoid a misdiagnosis of malignancy, and prevent unnecessary diagnostic work-up and treatment.

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