Circulating Russell-Body-Containing Lymphoid Cells in an Immunocytoma Patient

Dr. van Greune,Department of Haematological Pathology,University of Stellenbosch Medical School,P.O. Box 19063, Tygerberg 7505 (Republic of South Africa) Immunoglobulin-containing inclusions in B-lymphoid cells are either globular/homogeneously electron dense or crystalline, with a variable periodic-acid Schiff (PAS) reaction. Globular-PASpositive inclusions are often referred to as Russell bodies. We describe a case of immunocytoma (diagnosed on bone marrow biopsy) in which most of the peripheral circulating lymphoid cells contained in-tracytoplasmic inclusions exhibiting the cytochemical and ultrastructural characteristics of typical Russell bodies. A 72-year-old male presented with a 3-week history of non-specific gastro-intestinal complaints, hepatomegaly, normocytic anaemia, IgMλ paraproteinaemia (11 g/l) and λ Bence Jones proteinuria. Bone marrow aspiration and trephine biopsy were obtained from the posterior iliac crest using Klima and Jamshidi needles, respectively. The biopsy was fixed in Zenkers’ solution, decalcified and embedded in paraffin wax. Immunohistochemical stains were done using the avidin-biotin complex technique (Dako, Denmark), modified by treating the sections with 0.1% trypsin for 9 min at 37 °C, blocking endogenous perox-idase with 1.5% H202 for 10 min and blocking non-specific binding with 5% skimmed milk buffer. The sections were stained for IgG, IgM, IgA, k and λ (Dako, Denmark) and with LN2 and MB2 (Clonab, FRG). For electron microscopy, the blood was collected in lithium heparin and the buffy coat processed according to standard technique. Thin sections (60-90 nm) were studied with a Hitachi H-600 electron microscope. No other tissue was available for investigation. The patient was lost to follow-up shortly after the bone marrow investigation. The blood count (Coulter STKS) showed: Hb 10.3 g/dl; WBC 13.4×109/1; platelets 253×109/1; lymphocytes 4.82×109/1; neutrophils 7.91×109/1 and monocytes 0.67 × 109/1, with 70% of the peripheral lymphocytes exhibiting prominent diastase-resistant PAS-positive inclusions (fig. 1). The lymphocyte population consisted of small well-differentiated cells, bigger lymphocytes with more cytoplasm and euchromatin and the occasional lymphoplas-macytoid cell. The marrow was hypercellular and intersti-tially infiltrated by a heterogeneous population of lymphoid cells, 64% containing inclusions and consisting predominantly of lymphocytes with some lymphoplasma-cytoid cells, plasma cells and immunoblasts. Single cells with PAS-positive intranuclear inclusions (Dutcher bodies) and an increased background population of mast cells were also evident. Most of the