B-cell lymphomas of extranodal origin.

Four hundred and forty-eight cases of malignant lymphoma in Tokyo University Hospital and Tokyo University Branch Hospital from 1955 to 1980 were found to be of extranodal origin. Extranodal lymphomas originated most frequently from the tonsils. The second commonest site was the stomach. The pharynx, nose and paranasal cavities, skin, subcutaneous tissue and soft part, intestine, orbita, and thyroid followed in order of frequency. These lymphomas of the nose and paranasal cavities, pharynx, tonsil, orbita, stomach, intestine, thyroid and skin were classified as B-cell type, T-cell type or "undecided," based on their morphology. In some of them, data from the immunoperoxidase test and/or immunological studies of surface markers were added. In lymphomas of the pharynx, tonsil, orbita, stomach, intestine and thyroid, the B-cell type was predominant. This suggests that in the extranodal sites in which a large amount of lymphoid tissue has been demonstrated physiologically and/or in which reactive lymphoid hyperplasia is frequently found, lymphomas of the B-cell type may occur more frequently. On the other hand, in the nose and paranasal cavities, lymphomas of the T-cell type were found as frequently as B-cell type. It is noteworthy that in all three cases that showed clinical features of so-called "rhinitis gangrenosa," had lymphomas belonging to the T-cell type. Also in the skin, T-cell lymphomas were found to be as common as B-cell type lymphomas, when cases of characteristic cutaneous T-cell lymphoma were excluded.