Fine needle aspiration cytology of a cutaneous metastasis from an extraadrenal paraganglioma: a case report.

BACKGROUND: Pheochromocytomas/paragangliomas are rare tumors originating from neuroectodermic cells, which metastasize in only 10% of cases. CASE: A case of cutaneous metastasis of an extramedullary paraganglioma was diagnosed by fine needle aspiration cytology (FNAC). A 39-year-old woman complained of a recently arisen subcutaneous nodule located on the scalp. Two years before she had suffered from a sporadic extraadrenal paraganglioma located on the sacrum, and it had been evaluated by FNAC. Smears were highly cellular and monomorphous; the cells were uniform and mainly isolated with round or ovoid nuclei, dense chromatin and inconspicuous nucleoli, if any. The cytoplasm was ill defined, clear or granular. Oval-spindle-shaped cells and occasional cells with larger nuclei were also observed. Abundant fibrillar material was present in the background, intermingled with the surrounding cells. The immunocytochemical staining performed on cell block sections showed negativity for CK20, HMB45 and LCA and positivity for chromogranin and S100. The cytologic diagnosis was a neuroendocrine tumor, consistent with a metastasis from the former sacral paraganglioma. CONCLUSION: On conventional samples the cytologic features of paraganglioma are typical enough to allow a cytologic diagnosis of a neuroendocrine tumor; this neoplasm should be considered in the differential diagnosis, even in such unusual locations, because of its unpredictable biologic behavior.