A case of solitary plasmacytoma of bone showing co-expression of both immunoglobulin light chains.

Ryota Matsuoka, Noriaki Sakamoto, Takayasu Kato, Shigeru Chiba, Masayuki Noguchi

European journal of medical research 2021 Dec 20

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Solitary plasmacytoma of bone (SPB) is a rare plasma cell neoplasm. It arises in bone as a single locus in the absence of any plasma cell myeloma lesions. Plasma cell neoplasms intrinsically express only one immunoglobulin light chain (IgL)-kappa or lambda-and using this fact, kappa/lambda deviation is the decisive factor for diagnosis. Co-expression of both IgLs in a single tumor cell is extremely rare. We report a case of SPB that arose in the vertebra of a 52-year-old Japanese woman. Histologically, the resected mass showed diffuse plasma cell proliferation. Dual IgL expression was detected by flow cytometry, immunohistochemistry, and in situ hybridization (ISH) targeting IgL mRNA. We have presented an extremely rare case of SPB showing dual expression of kappa and lambda IgLs. This unusual case of plasma cell neoplasia might represent a possible exceptional example of failure of "IgL isotypic exclusion." © 2021. The Author(s).

Citation

Ryota Matsuoka, Noriaki Sakamoto, Takayasu Kato, Shigeru Chiba, Masayuki Noguchi. A case of solitary plasmacytoma of bone showing co-expression of both immunoglobulin light chains. European journal of medical research. 2021 Dec 20;26(1):148