Primary mediastinal clear cell lymphoma

Abstract

This is a report on 8 mediastinal tumours that occurred in young adults (19-43 years, mean: 29.4); predominantly in females (6/8). Initial symptoms consisted of thoracic pain and venectasia and in only one case in B symptoms. After surgical tumour reduction, radiation and/or chemotherapy, local recurrence was observed in each case under clinical care; abdominal spread is presently suspected in 3 patients; 3 died 11, 13 and 22 months after diagnosis. None developed leukaemia. The tumours are B-cell neoplasms with a characteristic immunophenotype: leucocyte common antigen+, common acute lymphoblastic leukaemia antigen-, B 1-antigen+, surface and cytoplasmic immunoglobulin-. Flow cytometry revealed DNA-diploidy in 7 cases and a moderately (3.2-3.8%) to extremely high (8.0-20.6%) S-phase component. The proliferation associated antigen Ki67 was detectable in 10-60% of the tumour cell nuclei, thus stressing the considerable or rapid growth. Histopathology is characterized by a diffuse growth pattern and a clearness and abundance of cytoplasm of the pleomorphic tumour cells, which vary in size and nuclear morphology from patient to patient. Apoptoses are more numerous than mitoses. Fibrosis and focal necrosis are common, sclerosis is present in 3 cases. We suggest that primary mediastinal lymphoma of B cell type is a novel B-lymphoma variant.

MedB-1, a human tumor cell line derived from a primary mediastinal large B-cell lymphoma

“…14 Med-B1 cells lack HLA-A,B,C ␣ heavy chains and ␤-2m, which is very often the case in mediastinal B-cell lymphoma. 1,21 This is also frequently encountered in mediastinal B-cell lymphoma. 1,22 Thus, the cell line features the very typical defect in major histocompatibility complex class I expression, the molecular mechanism of which remains elusive.…”

“…It occurs in all age groups but most frequently in young adults. [1][2][3][4][5][6][7] The typical localization is the anterior mediastinum, and thymic involvement has been repeatedly demonstrated. Therefore, it is assumed that this B-cell lymphoma is a primary thymic tumor.…”

Further delineation of chromosomal consensus regions in primary mediastinal B-cell lymphomas: an analysis of 37 tumor samples using high-resolution genomic profiling (array-CGH)

“…1 Due to the location and morphologic characteristics, PMBL is a unique lymphoma subset that probably derives primarily from asteroid thymic B cells. [2][3][4][5] PMBL is positive for CD19, CD20, CD45, and often CD30, CD79a, CD11c, CD23 and negative for CD10 and CD21. 6 Highly characteristic is a lack of immunoglobulin surface antigen and a missing expression of major histocompatibility complex (MHC) class I and II molecules.…”

Isotype-switched immunoglobulin genes with a high load of somatic hypermutation and lack of ongoing mutational activity are prevalent in mediastinal B-cell lymphoma

“…To obtain information on isotype switching in this constitutively Ig Ϫ tumor, 5,6,[15][16][17] we determined the presence of lymphoma-specific Ig H messenger RNA (mRNA). Finally, since DNA sequence analysis was inconclusive in explaining the lack of immunoglobulin protein in PMBL, we measured antibody protein expression of a mediastinal B-cell lymphoma cell line, MedB-1, and assessed its amenability to physiologic regulators of immunoglobulin expression.…”