Metastatic parachordoma.

Tumors traditionally classified as parachordomas are rare, usually indolent, soft tissue neoplasms. This case report describes a 6-year-old girl with a mass in her left forearm measuring 11 × 6 cm. Foci of moderate nuclear atypia and various areas of necrosis were found in the tumor. Lung metastases were detected 3 months after diagnosis. Immunophenotyping revealed a strong, diffuse expression of pancytokeratin, S-100 protein, vimentin, glial fibrillary acidic protein and focal expression of chromogranin A. This is the fifth documented report on cases of metastasized parachordomas. It is rare for these neoplasms to show such aggressive behavior; moreover, immunoreactivity to chromogranin A is unexpected in these tumors. The relationship between the so-called parachordomas and soft tissue myoepithelioma/mixed tumors is discussed, including the recently defined pediatric myoepithelial carcinoma. [ABSTRACT FROM AUTHOR]