Ossifying fibroma: an uncommon differential diagnosis for T2-hypointense sinonasal masses.

Ossifying fibroma is a benign fibro-osseous lesion that occurs most commonly in the mandible of female patients. In rare cases, it affects the nasal cavity. The magnetic resonance imaging features may vary depending on the amount of fibrous and bony tissue in its composition. In these tumors, T2-hypointensity is a feature described in the peripheral ossified areas of the lesion, but it may present diffusely, especially when the degree of ossification is extensive. In this scenario, this particular characteristic on T2-weighted imaging is superimposable to the commonly described appearance of other lesions, such as non-Hodgkin's lymphoma, melanoma, and other sinonasal neoplasms with high cellularity and high nucleocytoplasmic ratio. In the present study, we report a case of ossifying fibroma of the nasal cavity that presented as a diffusely and homogeneously T2-hypointense mass, a finding that may cause difficulty in the differential diagnosis with other expansive sinonasal lesions.