Fibrodysplasia ossificans progressiva presenting as a neck mass

Objective To report a case of fibrodysplasia ossificans progressiva (FOP) initially presenting as a neck mass and alert the practicing otolaryngologist to the imperative to avoid harmful biopsy. Case A 2-year-old male presented with a firm left posterior neck mass and bilateral great toe malformations. Imaging was non-diagnostic and after 2 weeks of antibiotics the lesion was larger. At surgical biopsy, the mass was pale, firm, and avascular. Histopathology showed low grade fibromyxoid tissue. Rheumatology service diagnosed FOP based on clinical examination of neck mass, bilateral great toe deformities, stiff joints. Biopsy proved unnecessary and the patient developed heterotopic ossification at the site of surgical trauma. The patient was started on anti-inflammatories and steroids with minimal benefit. This case highlights the need for a broader understanding among clinicians who may encounter patients with FOP regarding the clinical aspects of diagnosis and the potential harm caused by surgical interventions.