[1438] Plasmacytoma Expressing Immunoglobulin A: A Clinicopathologic Analysis of 8 Cases

H Shao, L Xi, M Raffeld, S Pittaluga, K Dunleavy, W Wilson, N Spector, D Azambuja, ES Jaffe. National Cancer Institute, National Cancer Institute, Bethesda, MD; Federal University of Rio de Janeiro, Rio de Janeiro, Brazil

Background: Extramedullary plasmacytoma (EMP) is a rare, typically solitary tumor occurring mostly in middle-aged to elderly patients. EMP is predominantly localized to the head and neck regions, and rarely in lymph nodes (LN). EMP often runs an indolent clinical course with a tendency for local recurrence, and occasional progression to multiple myeloma in about 15% of patients. Only occasional cases of plasmacytoma expressing IgA have been reported in the literature, and the clinical and pathologic features of these tumors remain poorly defined.
Design: 11 cases of plasmacytoma expressing IgA were retrieved from the consultation files of the Hematopathology section at NIH; 8 cases presenting with nodal disease were selected for further characterization. Clinical information, results of cytogenetic analysis, and histologic and immunostained slides were reviewed. For clonality analysis, PCR studies of IGH and IGK gene rearrangements were performed on genomic DNA isolated from paraffin embedded tissue sections.
Results: There were five males and three females; age range was 17 to 66 years (median, 39 years). Four of the patients were younger than 30-years-old including 3 males and 1 females. 62.5% (5/8) of the patients had evidence of immune system dysfunction, including one with human immunodeficiency virus infection, one with T-cell deficiency, two with autoantibodies, and one with a history of arthritis. 6 cases had involvement of multiple LN. IgA M-spike was detected in 5/6 cases, and the M-protein was nearly always less than 30 g/L. All patients had an indolent clinical course without progression to multiple myeloma. Histologically, IgA plasmacytoma showed either interfollicular or diffuse pattern of plasma cell infiltration. The plasma cells were generally of mature Marschalko type with little or mild pleomorphism and exclusive expression of monotypic IgA. There was no preferential expression of kappa or lambda light chains (ratio 5:3). Clonality was demonstrated by PCR in 4 cases, by cytogenetic analysis in 1 case, and by immunofixation in 1 case. Clonality did not correlate with pattern of lymph node infiltration.
Conclusions: Plasmacytoma expressing IgA may represent a distinct form of extramedullary plasmacytoma with unique features including younger age at presentation, frequent nodal disease and a benign clinical course.
Category: Hematopathology

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 204, Tuesday Morning


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