Gangliocytic paraganglioma associated with duodenal adenocarcinoma. Case report with immunohistochemical evaluation.

We present the first reported case (to our knowledge) of duodenal gangliocytic paraganglioma (GPG) to be associated with an underlying invasive adenocarcinoma. The patient, a 71-year-old man, presented with epigastric tenderness and was found to have metastatic adenocarcinoma in two regional lymph nodes. Immunohistochemical evaluation of the GPG demonstrated positive staining for gastrin, glial-fibrillary acidic protein, glucagon, neuron-specific enolase, pancreatic polypeptide, S100 protein, somatostatin, and substance P. The clinical, pathologic, and immunohistochemical features of GPG are discussed, with a review of the literature.