One Patient, Two Uncommon B-Cell Neoplasms: Solitary Plasmacytoma following Complete Remission from Intravascular Large B-Cell Lymphoma Involving Central Nervous System

Abstract

Second lymphoid neoplasms are an uncommon but recognized feature of non-Hodgkin's lymphomas, putatively arising secondary to common genetic or environmental risk factors. Previous limited evaluations of clonal relatedness between successive mature B-cell malignancies have yielded mixed results. We describe the case of a man with intravascular large B-cell lymphoma involving the central nervous system who went into clinical remission following immunochemotherapy and brain radiation, only to relapse 2 years later with a plasmacytoma of bone causing cauda equina syndrome. The plasmacytoma stained strongly for the cell cycle regulator cyclin D1 on immunohistochemistry, while the original intravascular large cell lymphoma was negative, a disparity providing no support for clonal identity between the 2 neoplasms. Continued efforts atcataloging and evaluating unique associations of B-cell malignancies are critical to improving understanding of overarching disease biology in B-cell malignancies.

Figure 1

Multiple hemorrhagic foci in bilateral cerebral hemispheres on MRI.

Figure 2

(a) Intravascular large B-cell lymphoma of brain. Hematoxylin and eosin (H/E) staining highlights intravascular large B-cell lymphoma in the brain, featuring large cells with moderate pleomorphism, vesicular chromatin, and prominent nucleoli. (b) Intravascular large B-cell lymphoma of brain. Immunohistochemistry confirms the B-cell lineage of the intravascular large cell lymphoma, being CD20+ CD3− and showing a high proliferation fraction by staining for Ki67. It displays a germinal centre phenotype by Hans' criteria, being CD10− bcl6+ MUM1− and lacks blimp1 expression.

Figure 3

MRI revealing large soft tissue mass in sacral region causing severe canal stenosis and compression of the sacral nerve roots resulting in cauda equina syndrome.

Figure 4

(a) Intravascular large B-cell lymphoma of brain. Neoplastic cells express bcl2 but lack cyclin D1 expression. In situ hybridization shows polytypic immunoglobulin light chain expression in the perivascular reactive plasma cells but not within intravascular neoplastic B cells. (b) Spinal plasma cell neoplasm. Apart from expression of CD138, the spinal plasma cell neoplasm displays expression of PAX5 and cyclin D1 but not CD56. In situ hybridization confirms lambda immunoglobulin light chain restriction.