B-cell Lymphoma with Vimentin-positive Cytoplasmic Inclusions

A 60-year-old woman complaining of cervical lymph-adenopathy was admitted to Keiyu General Hospital, Yokohama. Malignant lymphoma involving systemic lymph nodes and the bilateral tonsils was suspected by computed tomography. The biopsy diagnosis of the cervical lymph nodes was B-cell lymphoma, diffuse medium-sized cell type. The cleaved centrocytic lymphoma cells were immunoreactive for CD20 and CD22 but negative for immunoglobulins. Characteristically, a considerable number of neoplastic lymphocytes possessed eosinophilic round inclusions in the cytoplasm. The inclusions were green in color by Papanicolaou staining, whereas they appeared vacuole like in Giemsa-stained preparations. Ultrastructural study confirmed the presence of aggregates of intermediate-sized filamentous structures mainly in the perinuclear area. The rough endoplasmic reticulum and Golgi apparatus were poorly developed. Immunocyto-chemical staining using cytologic specimens and fresh-frozen sections disclosed that the inclusions were composed of vimentin filaments. Morphologic similarities to signet ring cell lymphoma are discussed. Acta Pathol Jpn 41: 473 479, 1991.