Plasmablastic Transformation of Low-grade B-cell Lymphomas

Abstract

Histologic transformation of low-grade B-cell lymphoma to diffuse large B-cell lymphoma is associated with poor prognosis. Although plasma cell differentiation is common in these lymphomas, an overt plasmablastic transformation (PBL-T) has been only rarely reported. We report 6 cases of PBL-T occurring in 3 chronic lymphocytic leukemias (CLL) and 3 follicular lymphomas. Five patients were men, and the mean age was 65 years (range, 52 to 72 y). None of them had history of immunodeficiency. In 3 cases the PBL-T occurred 34 to 85 months after the initial diagnosis, and in 3 it was detected simultaneously with the small cell component at diagnosis. All patients received chemotherapy after transformation, and 4 died 4 to 24 months after this diagnosis. In 3 cases, PBL-T occurred in an extranodal site. All PBL-Ts had immunoblastic morphology with admixed plasma cells, were CD20 and PAX5 negative, expressed λ light chain, and 5 were CD138 positive. All cases were negative for HHV8, and only 1 PBL-T was Epstein-Barr virus positive. Evidence of a clonal relationship between the small cell and PBL-T components was found in 5 cases. In 2 CLL cases, both components had 13q deletions, and in all follicular lymphoma cases both components harbored the t(14;18) translocation. MYC translocations were observed in 2 cases transformed from a CLL. In conclusion, PBL-T expands the clinicopathologic spectrum of the transformation of low-grade B-cell lymphomas. These transformed tumors are clinically, histologically, and phenotypically similar to primary plasmablastic lymphomas, but they are not associated with immunodeficiency and rarely have Epstein-Barr virus infection or MYC alterations.

Histologic transformation of chronic lymphocytic leukemia/small lymphocytic lymphoma

“…Most patients who develop RS-PBL are men, 52-77 years of age. A serum or urine paraprotein can be detected in some patients [18]. In addition to typical plasmablastic features, residual CLL/SLL cells may be identified in some areas.…”

“…CD5, CD20, PAX5, and IRF8 are commonly negative. Molecular studies have shown monoclonal IGH [18] and MYC rearrangement [47]. The prognosis of patients with RS-PBL is grim.…”

“…3). These neoplasms most commonly arise de novo in the setting of immunodeficiency, however, a few cases of plasmablastic lymphoma (RS-PBL) arising in patients with CLL/SLL has been reported [18,19,47]. Most patients who develop RS-PBL are men, 52-77 years of age.…”

“…of lesions detectable by 18 FDG-PET is highly sensitive in excluding RS, with a negative predictive value of up to 97%, the positive predictive value of 18 FDG-PET/CT for RS is generally proportional to the SUV; an SUV > 10 is predictive of the presence of aggressive lymphoma with 80% confidence, and an SUV > 13 with >90% confidence [4][5][6][7].…”

“…Hypercalcemia, new onset of absolute lymphocytosis 5.0 3 10 9 /L, and thrombocytopenia <100 3 10 9 /L often accompany RS, but these findings are not by themselves a reliable predictor of RS [8][9][10][11][12][13][14][15][16][17][18][19].…”