Trismus and multifocal soft tissue ossification. A presentation of fibrodysplasia ossificans progressiva?

A 21-year-old female patient presented with trismus, initially diagnosed as related to pericoronitis. Computed tomography demonstrated heterotopic soft tissue ossification involving both medial pterygoids which was later followed by similar features in the submandibular muscles and right quadriceps. A variant of fibrodysplasia ossificans progressiva was considered the likeliest diagnosis. The computed tomographic features of the condition and the importance of early diagnosis are stressed.