J Korean Med Sci.  1997 Oct;12(5):443-446. 10.3346/jkms.1997.12.5.443.

Cleaved variant of plasmacytoma with myelomonocytic differentiation--immunohistochemical and ultrastructural studies

• Go JH
• Ko YH
• Ree HJ

• KMID: 1081037
• DOI: http://doi.org/10.3346/jkms.1997.12.5.443

Abstract

Although plasma cells are terminally differentiated B cells, neoplastic plasma cells frequently express not only pre-B cell antigen, but also megakaryocytic, myelomonocytic, or erythroid markers. Since morphologic diagnosis of plasmacytoma is based on the recognition of neoplastic cells closely resembling normal plasma cells, unusual morphologic variants of neoplastic cells associated with these aberrant immunohistochemical features frequently cause diagnostic difficulty. The authors report a case of plasmacytoma with cleaved nuclei and myelomonocytic features occurring in the clavicle. The tumor was composed of immature plasma cells showing irregular, cleaved, and multilobated nuclei and abundant cytoplasm with prominent eosinophilic granules. A few tumor cells showing recognizable plasmacytic differentiation were admixed within the tumor. Immunohistochemically, the tumor cells expressed CD45RB, CD68, lysozyme, myeloperoxidase and kappa light chain with focal positivity for lambda chain. Ultrastructurally, the tumor cells contained numerous membrane bound electron dense lysosomal granules, some of them resembling Auer rods, as well as rough endoplasmic reticula arranged in lamellated stacks. Small biopsied nasal mucosal tissue in same patient revealed well differentiated plasmacytoma composed of tumor cells showing round, eccentric nuclei devoid of marked nuclear cleavage and cytoplasmic granularity. Immunohistochemically, these cells were kappa(+), lambda(-), myeloperoxidase(-), lysozyme(-) and CD68(-).

MeSH Terms

Adult
Antigens, Differentiation, Myelomonocytic/metabolism
Case Report
Cell Differentiation
Female
Human
Plasma Cells/ultrastructure
Plasma Cells/pathology*
Plasmacytoma/ultrastructure
Plasmacytoma/pathology*