A unique temporal bone lesion resembling juvenile active ossifying myxoma.

Juvenile active ossifying fibroma (JAOF) is a lesion characterized by early age of onset, slow growth, frequent recurrence, and locally aggressive behavior. Histologically, it consists of three major components: cellular fibrous stroma, osteoid bodies, and myxomatous matrix, which may become cystic. This article describes a case of a slowly growing destructive lesion of the mastoid in a 2-year-old girl with histologic features resembling those of juvenile active ossifying myxoma (JAOM). Histologically, its prominent features were myxoid and fibromyxoid stroma with cystic areas, vascular spaces, bone, and multinucleated giant cells. This is the first pediatric temporal bone lesion with these features recorded These histologic components led to the diagnosis of JAOM of the temporal bone, probably developing in relation to the development of the mastoid air spaces.