Increased numbers of lymphocytes with single class surface immunoglobulins in reactive hyperplasia of lymphoid tissue.

Forty-seven lymph nodes and one stomach exhibiting reactive hyperplasia from 40 patients were examined by morphologic and immunologic methods. Twelve lymph nodes and one stomach from ten patients had a significantly increased number (greater than 25%) of lymphocytes, with single class surface immunoglobulins or plasma cells, and plasmacytoid lymphocytes secreting single class immunoglobulins. In three cases, a diagnosis of malignancy was subsequently made on the basis of morphological and immunological evidence of tumor in other tissue. Five patients had collagen disorders, two had a persistent unexplained hypergammaglobulinemia, and two had no recognized associated disease. The significance of an increase of B lymphocytes with single class surface immunoglobulins in these cases is presently not clear, but patients with similar findings should have extensive investigation and persistent follow-up.