Conclusion:
This unique case associate two complications of a marginal zone lymphoma with plasmacytic differentiation and IgM paraprotein. This observation underlines the need to search for a B lymphoproliferative disorder after an histological CSH diagnosis and to hypothesize that a B-lymphoproliferative disorder with plasmacytic differentiation and paraprotein secretion other than WM can induce neurological presentations similar to BNS.
Fig1 Cerebral MRI. Leptomeningeal contrast enhancement in T1 Gadolinium sequence before treatment (arrow) (1A). Disappearance of the leptomeningeal contrast enhancement in T1 Gadolinium sequence after treatment (1B). Hypersignal lesions in the supra-tentorial white matter in T2 FLAIR sequence before treatment (arrow) (1C). Stabilization of hypersignal lesions in the supra-tentorial white matter in T2 FLAIR sequence after treatment (arrow) (1D).
Fig2 Colon biopsy. Submucosal clusters of histiocytes with crystalline eosinophilic cytoplasm inclusions (2A: HPS x 2.5, 2B: HPS x 40)
Fig3 Bone marrow biopsy. Hypercellular bone marrow with a discret lymphoid infiltrat (arrow) (3A: HPS x 2.5). Histiocytes with abundant crystalline eosinophilic cytoplasmic inclusions were identified, scattered or in clusters (3B: HPS x 40). The lymphoid infiltrate is made of a mixture of a B and T lymphocytes (3C: CD20 x 5, 3D: CD3 x 5). The plasma cells represented 5 to 10% of the bone marrow cellularity (3E: CD138 x 5).
Fig4 Lymph node biopsy. Massive infiltration by the same crystalline histiocytes as observed in colon biopsy and bone marrow, associated with small lymphoid nodules at the periphery of the lymph node (4A: HPS x 2.5). The crystalline histiocytes are admixed with numerous plasma cells (4B: HPS x 40).