title: Primary Epithelioid Sarcoma of the Zygomatic Bone.
abstract: Primary epithelioid sarcoma (ES) of bone is extremely rare with only 2 reported cases in the English literature. A previously healthy 18-year-old man presented with a 6-month history of right facial numbness and tingling and right eye diplopia. A computerized tomography scan revealed an ill-defined mass with dense osseous matrix centered in the right zygomatic bone. An outside biopsy was read as osteosarcoma. The resection specimen revealed large epithelioid and spindle cells embedded in a prominent hyalinized matrix with focal metaplastic bone formation. The tumor cells were strongly and diffusely positive for AE1/AE3 and epithelial membrane antigen, but a definitive diagnosis of ES was not immediately reached due to the presence of dense hyalinized matrix and weak expression of SAT2B by tumor cells. Deficient INI1 protein expression by immunohistochemistry and homozygous loss of the SMARCB1 gene by chromosomal microarray analysis ultimately justified this tumor's designation as ES.
authors.affiliation: 1 Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, Los Angeles, California.
authors.forename: Henry
authors.initials: H
authors.lastname: Tran
authors.affiliation: 1 Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, Los Angeles, California.|2 Keck School of Medicine, University of Southern California, Los Angeles, California.
authors.forename: Nick
authors.initials: N
authors.lastname: Shillingford
authors.affiliation: 2 Keck School of Medicine, University of Southern California, Los Angeles, California.|3 Division of Hematology, Department of Pediatrics, Children's Hospital Los Angeles, Los Angeles, California.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Thomas
authors.affiliation: 2 Keck School of Medicine, University of Southern California, Los Angeles, California.|4 Plastic and Maxillofacial Surgery, Children's Hospital Los Angeles, Los Angeles, California.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Hammoudeh
authors.affiliation: 1 Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, Los Angeles, California.|2 Keck School of Medicine, University of Southern California, Los Angeles, California.
authors.forename: Shengmei
authors.initials: S
authors.lastname: Zhou
mesh_terms: D000293:Adolescent; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001706:Biopsy; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D018396:Mucin-1 / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D012516:Osteosarcoma / Q000000981:diagnostic imaging / Q000473:pathology; D000071796:SMARCB1 Protein / Q000235:genetics / Q000378:metabolism; D012509:Sarcoma / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed; D015050:Zygoma / Q000000981:diagnostic imaging / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D018396:Mucin-1; D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human
keywords: INI1; bone tumors; epithelioid sarcoma; head and neck tumors; zygomatic bone