Case report: Sinonasal teratocarcinosarcoma.

Sinonasal teratocarcinosarcoma (SNTCS) is a rare, teratoma-like lesion of the nasal cavity and paranasal sinus. To the best of our knowledge, SNTCS is highly malignant. We report a case of SNTCS arising in the nasal cavity of a 71-year-old male who complained of nasal obstruction and epistaxis. In spite of intensive treatment, the tumor recurred three times and the patient died from a local extension into the anterior cranial fossa 7 years after initial onset. The resected tumors consisted of variegated components, such as epithelial elements, including cystic, ductal and glandular structures occasionally associated with squamous differentiation, neuroectodermal ones exhibiting neural rosette formation, and mesenchymal ones with prominent rhabdomyoblastic differentiation. Immunohistochemical and ultrastructural studies clearly demonstrated characteristic cellular differentiation of each component. These three principal elements were often topographically related and showed morphological transition with each other. These findings suggest the derivation of divergent components from common progenitor cells. Although the cellular atypia of the primary lesion was inconspicuous, the recurrent tumors became anaplastic and mitotically active. Histologic anaplasia may be somewhat related with aggressiveness of recurrent lesions. Appropriate sampling of specimens, and awareness of this rare teratoid tumor are important to make the correct diagnosis.