IgM lambda globular cytoplasmic inclusions in chronic lymphocytic leukaemia resembling immunocytoma

Abstract

In a 64-year-old female with chronic lymphocytic leukaemia, nearly 50% of the lymphocytes presented one or several globular intracytoplasmic inclusions resembling Russell bodies which were characterized by immunofluorescence as IgM lambda. On electron microscopy, the inclusions looked like cisternae of the rough endoplasmic reticulum. Surface membrane Ig was not detected and the serum IgM was low. The histology of a lymph node showed a lymphocytic proliferation with evidence of Ig synthesis, compatible with immunocytoma. The aggressive course of the disease necessitated polychemotherapy. This case represents an unusual ill-defined lymphoproliferative disorder, lying between the B-CLL and a non-secretory macroglobulinaemia.