Sinusoidal large cell ("histiocytic") lymphoma.

A sinusoidal pattern of involvement by large cell ("histiocytic") lymphoma was present focally or throughout the initial lymph node biopsies of 18 patients. Clinical, ultrastructural, histochemical, and immunopathologic studies confirm that this is lymphoma. The recognition of this variant of large cell lymphoma is important in avoiding the common misdiagnoses, which were metastatic carcinoma, metastatic malignant melanoma, and malignant histiocytosis. The number of patients is too small for comment on whether the pattern has prognostic implications.