Intriguing Morphology of IgG/Lambda Secreting Myeloma Cells

Abstract

Myeloma cells are known to show varied morphology and various types of nuclear or cytoplasmic inclusions. There are a few reports of myeloma with presence of pseudo-Gaucher type histiocytes; however myeloma cells itself resembling storage histiocytes is distinctly uncommon. We report images of plasma cells resembling storage cells from a case of IgG/lambda plasma cell myeloma. Hematopathologist must be aware of such varied morphology of plasma cells especially while dealing with extra medullary plasmacytomas.

Description

A 64-year-old gentle man with history of type 2 diabetes mellitus presented with low backache of 2 months duration. On evaluation, he was found to have anemia (50 g/l), reversed albumin-globulin ratio (0.31), hypercalcemia (14.1 mg/dl), renal failure (serum creatinine 3.1 mg/dl), osteolytic vertebral bone lesions, Monoclonal protein-band (64.8 g/l); and immunofixation electrophoresis showed positivity for γ-heavy and λ-light chains. Bone marrow aspirate showed >80 % plasma cells and marked reduction of all other hematopoietic cells. Most of the cells appeared large with multivacuolated cytoplasm (Fig. 1), which was negative for periodic acid Schiff stain (PAS). The trephine biopsy showed sheets of cells having multivacuolated cytoplasm and distinct cytoplasmic borders mimicking storage disorder (Figs. 2, 3). The interstitial spaces showed deposition of amyloid like material (Fig. 3). The cells were diffusely positive for CD138 (Fig. 4) confirming them to be plasma cells. Myeloma cells are known to show varied morphology and various types of nuclear or cytoplasmic inclusions [1]. The unusually rare PAS negative foamy morphology of plasma cells mimicking storage disorder in our case also reminds of the similar appearance of the renal tubule epithelial cells seen in λ-light chain restricted myeloma associated light chain proximal tubulopathy. There are a few reports of myeloma with presence of pseudo-Gaucher type histiocytes; however myeloma cells itself resembling storage histiocytes is distinctly uncommon [2–5]. Hematopathologist must be aware of such varied morphology of plasma cells especially while dealing with extra medullary plasmacytomas.

Fig. 1.

Bone marrow aspirate smear shows multivacuolated plasma cells and a vacuolated background (May Grunwald Giemsa stain; 1000×)

Fig. 2.

Trephine biopsy shows sheets of plasma cells with foamy vacuolated cytoplasm (Haematoxylin and Eosin stain; 100×)

Fig. 3.

Interstitial amyloid deposits admixed with plasma cells (Haematoxylin and Eosin stain; 200×)

Fig. 4.

Immunohistochemistry for CD138 shows membranous positivity in plasma cells (IHC CD 138; 200×)

Compliance with Ethical Standards

Conflict of interest

All the three authors declare that they have no conflict of interests.

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from all individual participants included in the study.