Richter's syndrome showing pronounced lymphadenopathy in response to administration of granulocyte colony-stimulating factor.

A patient with Richter's syndrome developed rapid generalized lymph node enlargement with a decrease of peripheral blood lymphocytes after recombinant human granulocyte colony-stimulating factor (rhG-CSF) therapy for neutropenia induced by chemotherapy. The lymphadenopathy subsided spontaneously following discontinuation of rhG-CSF medication. Reinstitution of rhG-CSF therapy was followed by the same response as during initial therapy. Histopathologically, the lesions were characteristic of diffuse large cell lymphoma (DLL) with no evidence of myeloid cell involvement. No spontaneous contraction of enlarged lymph nodes followed withdrawal of the second course, but the enlargement subsided with chemotherapy. The patient died of myocardial infarction. All residual tumors examined post mortem presented microscopic features of small lymphocytic lymphoma (SLL), and G-CSF receptor was demonstrated on these neoplastic cells by Northern blot hybridization analysis. This observation indicates that some B cell malignancies may retain G-CSF receptor and respond to G-CSF.