Sinonasal Teratocarcinosarcoma: A Case Report in a 13-Year-Old Male.

Teratocarcinosarcoma is rare malignant sinonasal neoplasm with immature and malignant endodermal, mesodermal, and neuroepithelial elements resembling immature teratoma, commonly with SMARCA4 loss or activating CTNNB1 mutation. The carcinoma component may be either squamous or adenocarcinoma and the mesenchymal component may be composed of spindle cells, cartilage, bone, smooth muscle, or skeletal muscle. Due to the uncommon nature of this malignancy, there are frequently diagnostic difficulties that result in management problems. Herein we report a teratocarcinosarcoma arising in the nasal cavity of a 13-year-old boy with CTNNB1 activating mutation and copy number variations by next-generation sequencing along with an abnormal karyotype. This tumor must be included in the differential of neoplasms with immature elements, more likely seen in pediatric patients.