title: Mediastinal lymphoblastic lymphoma with an immature B-cell immunophenotype.
abstract: A 19-year-old woman presented with a large mediastinal mass, histologically shown to be malignant lymphoma of lymphoblastic type (LBL). Immunophenotypic and gene rearrangement analysis unequivocally demonstrated that the neoplasm was of B-cell lineage. The neoplastic cells expressed terminal deoxynucleotidyl transferase, the pan-B cell antigens CD19, CD20, and CD22, and were negative for immunoglobulins and numerous T-cell antigens tested. Southern blot analysis showed rearrangement of one allele of the immunoglobulin heavy chain gene while the immunoglobulin kappa and T-cell receptor beta chain genes were in the germline configuration. Thus, the immunophenotypic and molecular findings in this case correspond to an early stage of B-cell differentiation, the pre-pre B-cell stage as has been named by others. In contrast with LBL of immature T-cell lineage, precursor B-cell LBLs involving the mediastinum are truly rare. Occasional cases have been reported that have arisen elsewhere and subsequently involved the mediastinum at time of relapse or tumor progression. Well-documented examples of immature B-cell LBL arising in the mediastinum are virtually unreported. The site and cell population giving rise to this neoplasm is unknown. However, origin from precursors of normal thymic medullary B cells is proposed as one possibility.
authors.affiliation: Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: C A
authors.initials: CA
authors.lastname: Sander
authors.forename: E S
authors.initials: ES
authors.lastname: Jaffe
authors.forename: F C
authors.initials: FC
authors.lastname: Gebhardt
authors.forename: T
authors.initials: T
authors.lastname: Yano
authors.forename: L J
authors.initials: LJ
authors.lastname: Medeiros
mesh_terms: D000328:Adult; D000483:Alleles; D015139:Blotting, Southern; D004262:DNA Restriction Enzymes; D005260:Female; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007145:Immunoglobulin kappa-Chains / Q000235:genetics; D016130:Immunophenotyping; D016393:Lymphoma, B-Cell / Q000175:diagnosis / Q000473:pathology*; D008479:Mediastinal Neoplasms / Q000175:diagnosis / Q000473:pathology*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis / Q000473:pathology*
chemical_list: D007143:Immunoglobulin Heavy Chains; D007145:Immunoglobulin kappa-Chains; D004262:DNA Restriction Enzymes