Cytodiagnosis of "signet-ring"-cell lymphoma.

An unusual case of malignant lymphoma with vacuolated cells was discovered during examination of pulmonary cytologic specimens. The diagnosis was confirmed by light and electron microscopic study of biopsy specimens. This variant of malignant lymphoma could be mistaken for adenocarcinoma or carcinoid tumor, but certain cytologic features common to malignant lymphomas should help to differentiate these neoplasms. The histologic, immunohistochemical and electron microscopic findings confirm the diagnosis. As more pathologists and cytologists become aware of this entity, additional cases will probably be reported. The significance of the morphologic findings is as yet uncertain.