Dual CD117 expression in gastrointestinal stromal tumor (GIST) and paraganglioma of Carney triad: a case report.

Carney triad is a rare syndrome, with only 20 complete cases reported. We report a 36-year-old white woman with complete Carney triad, including metastatic gastric stromal tumor (GIST), pulmonary chondroma, and nonfunctioning extra-adrenal paraganglioma. Immunohistochemistry was positive for CD34 and CD117 (c-kit) in the GIST, and positive for chromogranin and CD117 in the paraganglioma. Ultrastructural studies demonstrated skeinoid fibers in the GIST. To our knowledge, this is the 21st complete Carney triad case reported and the first report of dual expression CD117 in both GIST and paraganglioma, a finding with intriguing pathogenetic implications related to the organization of the autonomic nervous system.