Primary tenosynovial giant cell tumor arising in the nasal cavity with molecular confirmation: the first reported case.

Tenosynovial giant cell tumors (TGCT) arising in the head and neck region are rare, and to date, no primary TGCT originating in the nasal cavity has been reported. Here, we report an extremely rare primary TGCT in the nasal cavity in a 28-year-old female. Computed tomography scan revealed a soft tissue density nodule measuring 1.6 × 1.4 cm in the left nasal cavity. Histologically, the tumor is mainly composed of mononuclear cells with round to oval nuclei, mild to moderate atypia. Scattered multinucleated giant cells and nests of foamy histiocytes were also identified. FISH analysis detected CSF1 gene rearrangement. Next-generation sequencing identified a CBL gene missense mutation (c. 1250C > G/ p.P417R). To the best of our knowledge, this is the first example of genetically confirmed TGCT in the nasal cavity. Our study broadens the anatomical spectrum of TGCT and highlights the inclusion of TGCT in the differential diagnosis of nasal cavity lesions.