Splenic marginal zone lymphoma with or without villous lymphocytes. Hematologic findings and outcomes in a series of 57 patients.

Background: Splenic marginal zone lymphoma (SMZL) is a well defined pathologic entity. However, questions regarding the bone marrow infiltration rate, the minimal diagnostic data set, and therapy remain unanswered.

Methods: Clinical-pathologic features and outcomes of 57 consecutive patients who had splenomegaly with no clinically significant lymphadenomegaly and who were diagnosed with SMZL with or without (+/-) villous lymphocytes (VL) were reviewed.

Results: SMVL +/- VL occurred mostly in elderly males (median age, 62 years +/- 10 years; male-to-female ratio, (1.85). Anemia was recorded in 49% of patients, and 30% of patients had moderate thrombocytopenia. Leukocytosis and leukopenia were found in 33% and 14% of patients, respectively, and typical VL were found in 84% of patients. Serology for hepatitis C virus infection was positive in 16% of patients, and a small monoclonal component was detected in 36% of patients. The bone marrow was infiltrated with an intrasinusoidal component in all patients. Thirteen patients were monitored using a watch-and-see policy, and they remained alive 1-5 years after diagnosis. Overall, 21 patients (36%) underwent splenectomy; and, in all patients, the diagnosis of SMZL was confirmed histologically in the surgical specimens. Twenty-five patients received single-agent therapy, which included either alkylators or pentostatine, and they achieved an overall response rate (ORR) of 65% and 87%, respectively: Polychemotherapy was administered to 6 patients (ORR, 83%). The median survival for all patients in the series was not reached, and it is expected that 70% of patients will be alive at 5 years.

Conclusions: Up to 20% of patients who had SMZL +/- VL could be monitored using a watch-and-wait policy. The bone marrow intrasinusoidal infiltration pattern may be a valuable diagnostic hallmark, thus obviating diagnostic splenectomy. The issues regarding prognostic stratification and the best therapeutic strategy need to be addressed in properly designed, prospective trials.