title: A Rare Pediatric Example of Subcutaneous Extraskeletal Osteosarcoma: A Case Report and Review of the Morphologic Differential Diagnosis.
abstract: Primary extraskeletal osteosarcoma is an exceedingly rare malignant neoplasm that accounts for approximately 1% of soft tissue sarcomas and most often occurs in the deep soft tissues of adults. Extraskeletal osteosarcoma is characterized by the production of osteoid, bone, and/or chondroid matrix. The diagnosis of extraskeletal osteosarcoma requires careful radiologic and clinical correlation to ensure that the patient does not have an underlying bone primary. This is a case report of primary subcutaneous extraskeletal osteosarcoma arising in the thigh of a 15-year-old girl with a complex karyotype, and the morphologic differential diagnosis is reviewed.
authors.affiliation: Departments of *Laboratory Medicine and Pathology, and †Orthopedic Surgery, Mayo Clinic, Rochester, MN.
authors.forename: Riyam T
authors.initials: RT
authors.lastname: Zreik
authors.forename: Reid G
authors.initials: RG
authors.lastname: Meyer
authors.forename: Robert B
authors.initials: RB
authors.lastname: Jenkins
authors.forename: Germán A
authors.initials: GA
authors.lastname: Norambuena
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Fritchie
mesh_terms: D000293:Adolescent; D005260:Female; D006801:Humans; D012516:Osteosarcoma / Q000473:pathology*; D012983:Soft Tissue Neoplasms / Q000473:pathology*; D013848:Thigh / Q000473:pathology