title: [A case of CD20 positive mediastinal rhabdomyosarcoma].
abstract: We present the case of a 16-year-old boy admitted with a large mediastinal mass.     Both in the mediastinal tru-cut biopsy and the bone marrow biopsy, a malignant     small round cell tumor was determined. The clinical diagnosis was leukemia or     lymphoma. The cytoplasmic CD20 expression was shown on the tumor cells of the     mediastinal tru-cut biopsy. Rhabdomyosarcoma was diagnosed by the flow     cytometric analysis and immunohistochemical demonstration of muscle markers.     Rhabdomyosarcomas are traditionally distinguished from lymphomas by their     absence of lymphoid markers such as CD20. But in this case we have encountered     CD20 expression in the tumor cells. This finding lead us to conclude that the     presence of a lymphoid phenotype does not absolutely exclude the diagnosis of     rhabdomyosarcoma.
authors.affiliation: Dr. Behçet Uz Çocuk Hastanesi, Patoloji ve Bölümü, İzmir, Türkiye. agdiniz@gmail.com
authors.forename: Gülden
authors.initials: G
authors.lastname: Dınız
authors.forename: Ferah
authors.initials: F
authors.lastname: Genel
authors.forename: Nur
authors.initials: N
authors.lastname: Yücel
authors.forename: Ayşen
authors.initials: A
authors.lastname: Türedı
authors.forename: Canan
authors.initials: C
authors.lastname: Vergın
mesh_terms: D018951:Antigens, CD20 / Q000096:biosynthesis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D002648:Child; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008479:Mediastinal Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D012208:Rhabdomyosarcoma / Q000175:diagnosis* / Q000378:metabolism*
chemical_list: D018951:Antigens, CD20; D014408:Biomarkers, Tumor