Nodular fasciitis of the lip mucosa: a rare but clinically important entity.

Oral nodular fasciitis (NF) is a rare benign entity of significant clinical importance, which presents as a rapidly growing soft tissue mass. Awareness of this entity is essential, because histologically it resembles a malignancy at first glance, owing to its spindled histological nature and numerous typical mitoses. Thus, it is often misdiagnosed as an aggressive sarcoma, resulting in unnecessary radical surgery. In total, 45 cases of oral NF have been reported since 1966, of which only 2 were reported in the dermatological literature. Patients with NF of the lip mucosa will frequently present to a dermatologist. Therefore, it is critical that dermatologists recognize this benign neoplasm to correctly manage it and avoid potentially catastrophic unnecessary surgery, as these lesions typically spontaneously resolve. We describe the clinical, histological and immunohistochemistry findings of NF in a 51-year-old woman, and discuss its differential diagnosis.