Monocytoid B-cell lymphoma: morphological variants and relationship to low-grade B-cell lymphoma of the mucosa-associated lymphoid tissue

• Published in: Histopathology Vol. 18; no. 5; p. 403
• Main Authors: Nizze, H, Cogliatti, S B, von Schilling, C, Feller, A C, Lennert, K
• Format: Journal Article
• Language: English
• Published: England 01-05-1991
• Subjects: Adult; Aged; Aged, 80 and over; Antibodies, Monoclonal; Antigens, Neoplasm - analysis; Female; Humans; Immunohistochemistry; Lymph Nodes - pathology; Lymphatic Metastasis - pathology; Lymphoid Tissue - pathology; Lymphoma, B-Cell - immunology; Lymphoma, B-Cell - pathology; Lymphoma, Non-Hodgkin - immunology; Lymphoma, Non-Hodgkin - pathology; Male; Middle Aged; Stomach Neoplasms - pathology
• ISSN: 0309-0167
• DOI: 10.1111/j.1365-2559.1991.tb00870.x

Twenty-eight cases of monocytoid B-cell lymphoma of lymph nodes and 16 lymph node metastases of primary gastric lymphomas, mostly low-grade B-cell lymphomas of mucosa-associated lymphoid tissue (MALT) type were investigated morphologically and immunohistochemically. Both groups showed the same morphological and immunohistochemical features: diagnostically important sites of infiltration were the sinuses and the marginal zones. The tumour cells were either medium-sized or small. The cytoplasm stained grey with Giemsa and was sometimes rather pale. In imprints the grey colour of the cytoplasm was a characteristic feature. The medium-sized cell type was more frequent; in one third of the cases it was combined with a prominent lymphoplasmacytic component from the same clone, and it resembled the monocytoid B-cells of the sinuses. The small cell type was less common, was not combined with a lymphoplasmacytic component and more closely resembled marginal zone cells. The difference was underlined by the negative reaction with the monoclonal antibody Ki-B3 in the small cell type, which, conversely, was positive in the medium-sized cell type and in the monocytoid B-cell reaction of the sinuses. Both of these cell types, however, showed a granular reaction with the new monoclonal antibody Ki-Mlp. The morphological and immunohistochemical parallels are arguments in favour of the assumption that monocytoid B-cell lymphoma is the nodal equivalent of low-grade B-cell lymphoma of MALT type. This is further supported by the fact that in nine of our 28 cases of monocytoid B-cell lymphoma, lymphomas were found simultaneously or subsequently in organs of the MALT. Monocytoid B-cell lymphoma must be differentiated from an infiltration that occurs in the form of clusters of monocytoid B-cells in other low-grade B-cell lymphomas, especially in immunocytoma with a high content of epithelioid cells.