[Aggressive fibromatosis of the frontal sinus].

Aggressive fibromatosis (AF) is a benign tumour with expansive and locally invasive growth. It is very rarely seen in the head and neck area. We present a 52-year-old female patient with AF localized to the left frontal sinus. The condition was initially mistaken for chronic sinusitis however computed tomography indicated tumour. A biopsy showed AF and the patient received surgical treatment. Symptoms, signs and treatment are discussed. It is concluded that AF in the sino-nasal tract is a rare, but potentially life threatening condition which might be mistaken for a simple sinusitis.