Infantile fibromatosis of the nose and paranasal sinuses: report of a rare case and brief review of the literature.

Infantile fibromatosis is an uncommon, usually cutaneous, nonmetastasizing but locally aggressive fibroblastic proliferation. Involvement of the sinonasal area is extremely uncommon, and only 5 cases have been previously reported. We report a new case, which occurred in a 2-year-old boy. The mass involved the nasal cavity and the paranasal sinuses and extended into the cranial cavity. We also discuss the clinicopathologic features of this lesion, including its ultrastructural characteristics, and we review the literature.