Uncommon location of myositis ossificans in a nine-year-old female German Shepherd dog. A case report

Objective: A case of muscular metaplastic ossification (myositis ossificans) in an unusual and hitherto undescribed location is described and compared with the more common forms of this entity. Materials and methods: A nine-year-old female German Shepherd dog had a recurrent, focal, suppurative inflammation in the ventrolateral cervical soft tissue with multiple fistulae and a firm, hardly movable mass in the skeletal muscle ventral of the first three cervical vertebrae. The lesion was examined clinically, radiologically and histopathologically. Results: The lesion was identified as myositis ossificans circumscripta in the ventral neck musculature with secondary perifocal suppurative dermatitis and cellulitis. Conclusion: In addition to the commonly described locations of myositis ossificans, this entity can also be found in more unusual locations, including the ventral neck musculature. Clinical relevance: The therapeutically and prognostically important diagnostic differentiation from ossifying malignancies including extraskeletal osteosarcoma can be achieved by histopathologic examination of surgical biopsies.