Variable expression of B-cell transcription factors in reactive immunoblastic proliferations: a potential mimic of classical Hodgkin lymphoma.

Reactive immunoblastic proliferations can histologically mimic classical Hodgkin lymphoma (CHL), and show diffuse CD30 expression in large cells. The lack of expression of CD15 in a subset of CHL further complicates their separation from immunoblastic proliferations. Loss of expression of B-cell transcription factors is frequently exploited in making a diagnosis of CHL; however, the staining patterns of B-cell transcription factors in immunoblastic proliferations have not been extensively studied. Thirty-three cases of reactive immunoblastic proliferations were evaluated using a panel of immunohistochemistry for CD30, CD15, CD20, CD3, κ, λ, CD45RB, MUM1, PAX5, OCT2, and BOB.1, as well as Epstein-Barr virus (EBV)/EBV-encoded ribonucleic acid in situ hybridization. A newly developed dual-color chromogenic in situ hybridization technology for detection of κ/λ mRNAs was also used. The majority of immunoblasts expressed CD30 in 14 of 33 (42%) cases; none expressed CD15. Loss or weak expression of at least 1 transcription factor in B immunoblasts, most commonly PAX5, was noted in 24 of 29 (83%) cases. A polytypic light chain expression pattern was detected by immunohistochemistry in 14 of 22 (63.6%) cases and by dual-color chromogenic in situ hybridization in 9 of 10 (90%) cases studied. EBV-encoded ribonucleic acid was detected in 8 of 33 (24.2%) cases, 5 of which were clinically unrelated to infectious mononucleosis. We conclude that B-cell transcription factors can show loss or weak expression in a significant proportion of reactive immunoblastic proliferations, and, therefore, staining for B-cell transcription factors together with CD30 should be interpreted with caution before a diagnosis of CHL is made.

Phase II study of fludarabine combined with interferon-alpha-2a followed by maintenance therapy with interferon-alpha-2a in patients with low-grade non-hodgkin's lymphoma.

Randomized trials suggest improved disease-free survival in low-grade non-Hodgkin's lymphoma (LGNHL) when interferon is combined with multiagent chemotherapy. This phase II trial was conducted to investigate the feasibility of combining fludarabine monophosphate (fludarabine) and IFN in a regimen for treatment of LGNHL. Twenty-one patients were evaluable. Median age was 55 years, and patients had been treated with an average of 1.7 chemotherapy regimens before enrollment. Patients received 25 mg/m2 of fludarabine intravenously on days 1 through 5 followed by 2 x 10(6) U/m2 of interferon-alpha-2a subcutaneously on days 22 through 26. Cycles were repeated every 4 weeks with delays and dose modifications for significant cytopenias. Patients were restaged after cycles 4 and 8, and those with at least a partial response to therapy were given maintenance therapy consisting of 2 x 10(6) U/m2 interferon-alpha-2a subcutaneously three times per week for 6 months. The overall response rate was 76% with a 25% complete response (CR) rate. Overall response rates were 75% (3/4 with 2 CR's) for chemotherapy-naive patients and 76% (13/17 with 3 CR's) for previously treated patients. Median time to progression was 12 months, and currently two patients are without evidence of progression at a median follow-up of 55 months. Grade III or greater toxicities included neutropenia (39%), anemia (17%), thrombocytopenia (5%), fevers/chills (5%), and fatigue (5%). Fludarabine and interferon can be effectively and safely combined in a regimen with significant activity against LGNHL. A modification of this regimen may be suitable for further study.