title: Benign calcifying fibrous-myofibroblastic tumor mimicking myositis ossificans in a 22-month-old girl.
abstract: Myositis ossificans circumscripta (MOC), with nonneoplastic heterotopic bone formation in soft tissue and skeletal muscle, is rare in children. Extraskeletal osteosarcoma is a very rare malignant mesenchymal neoplasm of soft tissues in children. At onset, it may be difficult to distinguish MOC from a musculoskeletal infection or neoplasm, particularly in the absence of trauma, and a biopsy is frequently required. However, differentiating MOC from malignant neoplasm is imperative. We describe the case of a 22-month-old girl who presented with a benign fibrous-myofibroblastic tumor mimicking MOC. However, extraskeletal osteosarcoma was also considered in the differential diagnosis due to the absence of attachment of the lesion to the skeleton. Pathologic findings after a previous needle biopsy and posterior marginal resection exclude both differential diagnoses. Close follow-up during 3 years postoperatively showed no signs of recurrence.
authors.affiliation: Servicio de Cirugía Ortopédica y Traumatología, Hospital Universitario Miguel Servet, Avda. de Isabel la Católica 1-3, 50009 Zaragoza, Spain. jgilalba@unizar.es
authors.forename: Jorge
authors.initials: J
authors.lastname: Gil-Albarova
authors.forename: Victoria Eugenia
authors.initials: VE
authors.lastname: Gómez-Palacio
authors.forename: Ana
authors.initials: A
authors.lastname: Fuertes-Zarate
authors.forename: Antonio
authors.initials: A
authors.lastname: Herrera
mesh_terms: D002114:Calcinosis / Q000209:etiology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D058628:Myofibroblasts / Q000473:pathology; D009221:Myositis Ossificans / Q000175:diagnosis*; D018218:Neoplasms, Fibrous Tissue / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D012516:Osteosarcoma / Q000175:diagnosis; D011859:Radiography; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D013848:Thigh