RECURRENT INTRAPULMONARY MALIGNANT SMALL-CELL TUMOR OF THE THORACOPULMONARY REGION WITH METASTASIS TO THE ORAL CAVITY - REVIEW OF LITERATURE AND CASE-REPORT

Malignant small cell tumor of the thoracopulmonary region (MSCT) was f irst described in 1979 and has been referred to as the Askin tumor. Th is malignant neoplasm is a member of the peripheral primitive neuroect odermal tumor (PPNET) family and typically involves the periosteum, so ft tissue, and extrapulmonary tissue of the thoracic wall. MSCT may al so involve the lung parenchyma by local extension or may arise de novo in peripheral lung tissue. Local recurrence, abdominal involvement by tumor extravasation across the diaphragm, and skeletal metastatic dis ease are relatively common. However, metastasis to the head and neck r egion and in particular to the oral cavity is extremely rare. We prese nt a recurrent intrapulmonary MSCT with metastasis to the oral cavity in an adolescent Hispanic boy, and review the literature regarding thi s member of the PPNET family. Differentiation from neuroblastoma may b e made based on immunoreactivity for beta(2) microglobulin and HBA71 a nd lack of immunoreactivity for chromogranin in PPNET and MSCT. Ultras tructural features commonly seen in MSCT and PPNET are round to ovoid tumor cells with occasional cytoplasmic processes with relatively few pleomorphic dense core granules. These tumors lack the gangliocytic an d Schwann cell differentiation that is characteristic of neuroblastoma . MSCT and PPNET have a common reciprocal cytogenetic translocation [t (11;22)q(24;q12)], which is shared with Ewing's sarcoma. Prognosis in MSCT is quite dismal, with a 2-year survival of 38% and a 6-year survi val of only 14%.