Pulmonary gangliocytic paraganglioma: a case report and review of the literature.

Gangliocytic paraganglioma (GP) is a rare histologic type of neuroendocrine tumors. We report a case of pulmonary GP in a 29-year-old male presenting with an asymptomatic endobronchial nodule. Grossly, the tumor showed a 4.0x3.8x3.5 cm well-defined nodule with yellowish cut surface. Microscopically, the tumor was composed of three distinct cellular types: epithelioid cells, ganglion-like cells and spindle cells. Meanwhile, transitional cells, having morphologic features between ganglion-like and epithelioid cells, were also presented. The epithelioid cells arranged in various morphologic architectures, including Zellballen, papillary, cystic and microcystic pattern. The epithelioid cells were positive for AE1/AE3, CAM 5.2, chromogranin A and synaptophysin. Ganglion-like cells showed immunoreactivity for chromogranin A and synaptophysin. A few ganglion-like cells were also positive for AE1/AE3 and/or CAM 5.2. The spindle cells were positive for S-100 protein and neurofilament. The transitional cells showed a similar immunohistochemical profile to the epithelioid cells. The authors believe stem cell theory is a reasonable explanation for the origin of GP. GP probably originate from some kind of mucosa associated stem cell which can differentiate into diverse cellular lineages.