MAL Expression in Lymphoid Cells: Further Evidence for MAL as a Distinct Molecular Marker of Primary Mediastinal Large B-Cell Lymphomas

Utility of CD200 immunostaining in the diagnosis of primary mediastinal large B cell lymphoma: comparison with MAL, CD23, and other markers

“…In all, 21 of 33 cases of primary mediastinal large B cell lymphoma (70%) and only 1/33 cases of diffuse large B cell lymphoma (3%) were initially found to immunoreactive for MAL. 10 Similarly, we found that 86% of primary mediastinal large B cell lymphoma and 3% of diffuse large B cell lymphoma cases were MAL positive. Finally, TRAF and REL were found to be immunoreactive in 48/78 cases (62%) and 31/48 cases (65%) of primary mediastinal large B cell lymphoma, respectively, and 20/173 cases (12%) and 28/160 cases (18%) of diffuse large B cell lymphoma.…”

“…Useful immunophenotypic markers for this purpose include CD15, a well-established marker of classical Hodgkin lymphoma that was found to be expressed in 17/20 cases (85%) of classical Hodgkin lymphoma but none of 27 cases of primary mediastinal large B cell lymphoma in a recent study by Salama et al 18 That study also found that CD23, one of the immunophenotypic markers useful for distinguishing primary mediastinal large B cell lymphoma from diffuse large B cell lymphoma, was expressed in 23/27 cases (85%) of primary mediastinal large B cell lymphoma but only 2/18 cases (11%) of classical Hodgkin lymphoma, in rare, scattered Reed-Sternberg cells. 18 MAL, another primary mediastinal large B cell lymphoma marker, was found to be expressed in only 3/31 cases of classical Hodgkin lymphoma, 10 so it too may be useful for this application. In contrast, TRAF and REL fail to distinguish primary mediastinal large B cell lymphoma from classical Hodgkin lymphoma: 21/25 cases (84%) of classical Hodgkin lymphoma were found to be immunoreactive for TRAF and 23/25 cases (92%) were immunoreactive for REL.…”

“…8,9 MAL antibody was previously described, 10 and staining was compared with that of mouse IgG control antibody diluted to identical protein concentration, to confirm staining specificity. For cases lacking prior immunostaining results for CD23, TRAF, and REL, immunostaining was performed using mouse monoclonal antibodies obtained from The Binding Site, Birmingham, AL; Santa Cruz Biotechnology, Santa Cruz, CA; and Calbiochem, San Diego, CA, respectively, and compared with mouse IgG control antibody diluted to identical protein concentration, to confirm staining specificity.…”

Expression pattern of intracellular leukocyte-associated proteins in primary mediastinal B cell lymphoma

“…Two protein markers characteristic of this tumor have been reported, namely MAL and FIG1. 23,24 The former is almost specific, 25 whereas FIG1 protein can be found in a significant minority of non-mediastinal diffuse large B cell lymphoma 6,23,25 Reed-Sternberg cells in the great majority of the cases of classical Hodgkin's disease are also clearly of B lymphoid origin but they show extensive disruption of the 'B cell program', that is, loss of B cell-associated molecules. [26][27][28][29][30] We recently provided further evidence for this phenomenon in an immunohistologic labeling study of five B cell-associated intracellular signaling molecules (BLNK, Syk, PLC-g2, Fyn and Lyn) in Hodgkin's disease.…”

Expression of TP73L is a helpful diagnostic marker of primary mediastinal large B-cell lymphomas

“…9,10 Primary mediastinal large B-cell lymphoma is considered a germinal-center or post germinal-center-derived lymphoma. [11][12][13] Despite a good clinico-pathological definition, and the fact that multiple molecular and cytogenetic alterations have been described, [14][15][16][17][18][19][20][21] the pathogenesis of primary mediastinal large B-cell lymphoma remains poorly understood. Recently, two groups defined a subset of gene transcripts that distinguish primary mediastinal large B-cell lymphoma from diffuse large B-cell lymphoma, 22,23 thus concluding an endless discussion about the nosologic distinction between the two entities.…”