Gaucher-like cells have occasionally been described in various haematological malignancies including Hodgkin's disease, non-Hodgkin's lymphoma, multiple myeloma (MM) and chronic myelogenous leukaemia (CML). A special type of this phenomenon is crystal-storing histocytosis or the so-called pseudo-pseudo Gaucher cells (PPGC) in which crystalline protein storage in macrophages is induced by paraproteinemia. Here we describe a 54-year-old man with an initial suspicion of Gaucher disease and monoclonal IgA gammopathy in whom a correct diagnosis of lymphoplasmacytic lymphoma (LPL) with massive infiltration of bone marrow and spleen by PPGC was confirmed by immunological, ultrastructural and molecular characterisation. The activity of leukocyte beta-glucocerebrosidase was only slightly elevated (7.3 nmol/mg protein/1 h) which ruled out the diagnosis of classic Gaucher's disease. The patient received two courses of CHOP without improvement and anti-CD20 monoclonal antibody (rituximab) with only temporary stabilisation. Subsequently, he underwent splenectomy because of prolonged severe pancytopenia and a suspicion of hypersplenism. After splenectomy significant haematological improvement was observed. Following anti-CD20 therapy, changes in immunoprofile and morphology of tumour cells were evident. Before treatment the population of LPL was more divergent, with expression of LCA, CD20, CD38 and CD138. However, after the treatment, there were more mature plasma cells which no longer expressed CD20 antigen-this picture was more consistent with the diagnosis of plasma cell myeloma. Similarly, in the spleen there were no CD-20-positive cells evident. Finally, the patient received two courses of VAD vincristine, doxorubicin, dexamethasone) with further haematological improvement but complete response was not achieved.