OBJECTIVES: To delineate the pathology of immunoglobulin M-producing multiple myeloma (IgM MM). METHODS: Clinicopathologic data were reviewed for 15 cases meeting World Health Organization criteria for MM and having a serum IgM paraprotein. Immunohistochemistry was performed on diagnostic bone marrow specimens for common B-cell and plasma cell markers. RESULTS: Of the 15 IgM MM bone marrows reviewed, 6 (40%) had lymphoplasmacytoid cytology, and 12 (80%) expressed CD19, CD20, and/or CD45. Cyclin D1 expression was common (11 cases, 73%) and usually associated with t(11;14). No cases expressed CD5 or had an associated CD5-positive B-cell population. CD117 was positive in 20% of cases. CONCLUSIONS: The frequent B-cell-associated antigen expression by IgM MM distinguishes it from other MM types, causing significant pathologic overlap with lymphoplasmacytic lymphoma (LPL). However, IgM MM is usually distinguished from LPL by aberrant cyclin D1 expression or t(11;14). Therefore, assessing for these abnormalities is recommended when evaluating bone marrow involvement by IgM-associated lymphoplasmacytoid disorders.
OBJECTIVES: To delineate the pathology of immunoglobulin M-producing multiple myeloma (IgM MM). METHODS: Clinicopathologic data were reviewed for 15 cases meeting World Health Organization criteria for MM and having a serum IgM paraprotein. Immunohistochemistry was performed on diagnostic bone marrow specimens for common B-cell and plasma cell markers. RESULTS: Of the 15 IgM MM bone marrows reviewed, 6 (40%) had lymphoplasmacytoid cytology, and 12 (80%) expressed CD19, CD20, and/or CD45. Cyclin D1 expression was common (11 cases, 73%) and usually associated with t(11;14). No cases expressed CD5 or had an associated CD5-positive B-cell population. CD117 was positive in 20% of cases. CONCLUSIONS: The frequent B-cell-associated antigen expression by IgM MM distinguishes it from other MM types, causing significant pathologic overlap with lymphoplasmacytic lymphoma (LPL). However, IgM MM is usually distinguished from LPL by aberrant cyclin D1 expression or t(11;14). Therefore, assessing for these abnormalities is recommended when evaluating bone marrow involvement by IgM-associated lymphoplasmacytoid disorders.
Authors: Inmaculada Ribera-Cortada; Daniel Martinez; Virginia Amador; Cristina Royo; Alba Navarro; Silvia Beà; Eva Gine; Laurence de Leval; Sergio Serrano; Andrew Wotherspoon; Dolors Colomer; Antonio Martinez; Elías Campo Journal: Mod Pathol Date: 2015-09-11 Impact factor: 7.842
Authors: Fernando Javier Bonilla-Valentín; Javier Cerra; William Cáceres-Perkins; Melissa Alsina Journal: Cancer Control Date: 2018 Jan-Mar Impact factor: 3.302