title: Clinicopathological features of five unusual cases of intraosseous myoepithelial carcinomas, mimicking conventional primary bone tumours, including EWSR1 rearrangement in one case.
abstract: Primary intraosseous myoepithelial tumours, including carcinomas are rare tumours. The concept of histopathological spectrum of these tumours is evolving. We describe clinicopathological and immunohistochemical features of five myoepithelial carcinomas, including molecular cytogenetic results in one case. There were five male patients within age-range of 8-40 years (median = 26). Four tumours occurred in the long bones, including two tumours, each, in the femur and fibula, respectively, while a single tumour occurred in the proximal phalanges. Tumour size (n = 3 cases) varied from 5.6 to 8.6 cm. On radiological imaging, most tumours appeared as expansile, lytic and destructive lesions. Two tumours appeared as sclerotic lesions. Two cases were referred with diagnoses of chondrosarcomas and a single case was referred with two different diagnoses, including an adamantinoma and an osteosarcoma. Histopathological examination in all these cases showed multinodular tumours comprising mostly polygonal cells, exhibiting moderate nuclear atypia and interspersed mitotic figures within a stroma containing variable amount of myxoid, chondroid, hyalinised and osteoid-like material. Three tumours revealed prominent squamous differentiation. By immunohistochemistry, tumour cells were positive for EMA (5/5), pan CK (AE1/AE3) (3/3), CK5/6 (4/4), CK MNF116 (1/1), S100 protein (5/5) and GFAP (3/5). The first tumour revealed EWSR1 rearrangement. The first patient, 10 months after tumour resection and a simultaneous lung metastatectomy, is free-of-disease (FOD). The second patient, 11 months after tumour resection is FOD. The third and fourth patients underwent wide resections and are on follow-up. The fifth patient underwent resections, including a lung metastatectomy. Primary intraosseous myoepithelial carcinomas are rare and mimic conventional primary bone tumours. Some primary intraosseous myoepithelial carcinomas display EWSR1 rearrangement. Squamous differentiation may be considered as an addition to their evolving histopathological spectrum. Immunohistochemical stains constitute as a necessary tool for arriving at the correct diagnosis in such cases, which has treatment implications. Surgical resection remains the treatment mainstay.
authors.affiliation: Department of Surgical Pathology, Tata Memorial Centre, Mumbai, India.
authors.forename: Bharat
authors.initials: B
authors.lastname: Rekhi
authors.affiliation: Department of Histopathology, Deenanath Mangeshkar Hospital, Pune, India.
authors.forename: Sujit
authors.initials: S
authors.lastname: Joshi
authors.affiliation: Department of Orthopaedic Oncology, Deenanath Mangeshkar Hospital, Pune, India.|Sancheti Institute for Orthopaedics and Rehabilitation, Pune, India.
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Panchwagh
authors.affiliation: Department of Surgical Oncology (Bone and Soft Tissues), Tata Memorial Centre, Mumbai, India.
authors.forename: Ashish
authors.initials: A
authors.lastname: Gulia
authors.affiliation: Asian Institute of Oncology, Mumbai, India.|SRL Diagnostics Centre of Excellence: Histopathology, Mumbai, India.
authors.forename: Anita
authors.initials: A
authors.lastname: Borges
authors.affiliation: Department of Medical Oncology, Tata Memorial Centre, Mumbai, India.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Bajpai
authors.affiliation: Department of Surgical Pathology, Tata Memorial Centre, Mumbai, India.
authors.forename: Nirmala A
authors.initials: NA
authors.lastname: Jambehekar
authors.affiliation: Asian Institute of Oncology, Mumbai, India.
authors.forename: Vinita
authors.initials: V
authors.lastname: Pant
authors.affiliation: Department of Orthopaedic Oncology, Deenanath Mangeshkar Hospital, Pune, India.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Mandholkar
authors.affiliation: Department of Surgical Oncology (Bone and Soft Tissues), Tata Memorial Centre, Mumbai, India.
authors.forename: Suman
authors.initials: S
authors.lastname: Byregowda
authors.affiliation: Department of Surgical Oncology (Bone and Soft Tissues), Tata Memorial Centre, Mumbai, India.
authors.forename: Ajay
authors.initials: A
authors.lastname: Puri
mesh_terms: D050398:Adamantinoma / Q000175:diagnosis / Q000235:genetics / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D014408:Biomarkers, Tumor / Q000235:genetics*; D001859:Bone Neoplasms / Q000175:diagnosis / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D002148:Calmodulin-Binding Proteins / Q000235:genetics*; D002648:Child; D002813:Chondrosarcoma / Q000175:diagnosis / Q000235:genetics / Q000473:pathology*; D003937:Diagnosis, Differential; D050701:E2F6 Transcription Factor / Q000235:genetics; D005269:Femur / Q000378:metabolism / Q000473:pathology; D005360:Fibula / Q000378:metabolism / Q000473:pathology; D050278:Finger Phalanges / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000235:genetics; D008297:Male; D009154:Mutation; D009208:Myoepithelioma / Q000175:diagnosis / Q000235:genetics / Q000473:pathology* / Q000601:surgery; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins / Q000235:genetics*; D009418:S100 Proteins / Q000235:genetics
chemical_list: D014408:Biomarkers, Tumor; D002148:Calmodulin-Binding Proteins; D050701:E2F6 Transcription Factor; C491744:E2F6 protein, human; C500986:EWSR1 protein, human; D005904:Glial Fibrillary Acidic Protein; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins; D009418:S100 Proteins; D007633:Keratins
keywords: EWSR1 rearrangement; Myoepithelial carcinoma; intraosseous myoepithelial carcinoma; rare bone tumours