Cutaneous myositis ossificans: an appropriate descriptor for fibro-osseous lesion of the external auditory canal.

Myositis ossificans is a benign pseudosarcomatous bone-forming lesion, histologically characterized by 2 components: a spindle (myo)fibroblastic cell population and a bony component that is arranged in a "zonal" pattern. It mainly affects the deep soft tissues of limbs, but its occurrence in other unusual locations, such as abdomen, inside nerves, and the subcutaneous fat, has been reported. The existence of myositis ossificans restricted to the skin has rarely been published under the term "fibro-osseous lesion of the external auditory canal." Here, we describe an additional case in the external auditory canal, emphasizing its differential diagnosis and alerting dermatopathologists and pathologists to the possibility of encountering such lesion in this anatomic location. For purposes of unifying terms, we propose that cases similar to ours be called "cutaneous myositis ossificans" instead of fibro-osseous lesion of the external auditory canal.