Fibrodysplasia ossificans progressiva

Objective: To report a case of fibrodysplasia ossificans progressiva (FOP) initially presenting as a neck mass and highlight the clinical relevance to the practicing otolaryngologist. Setting: Tertiary care children's hospital. Methods: Chart review, case report Results: A 2 yo male presented with a 5-week history of a firm and enlarging left posterior neck mass. CT scan showed a hypodense area infiltrating the posterior neck musculature. Infected lymphangioma was first considered and initial treatment consisted of antibiotics and oral steroids. On follow up, the lesion was even larger. At surgical biopsy, the mass was pale, gray, firm, avascular, and infiltrating the soft tissues. The histopathologic results showed low grade fibromyxoid and adipose tissue favoring lipofibromatosis. Rheumatology service was consulted and made the diagnosis of FOP based on these pathological findings, bilateral great toe deformities, and stiff joints. Genetic testing confirmed the diagnosis. The patient was started on anti-inflammatories and steroids. Summary: FOP is a rare disease characterized by malformation of the great toes and heterotopic ossification of skeletal muscle and connective tissue. The chest cavity becomes restricted leading to an early death due to thoracic insufficiency syndrome. Surgical intervention leads to explosive flare-up and painful new bone growth. Knowledge of this disease can be valuable to otolaryngologists to facilitate early diagnosis and prevent aggressive surgical management which can lead to harmful progression of disease. As in our case, this rare condition can manifest primarily as a neck mass and present a diagnostic challenge for the practicing otolaryngologist.