Quantitative determination of T cells in ocular lymphoid infiltrates. An indirect method for distinguishing between pseudolymphomas and malignant lymphomas

D. M. Knowles 2nd and F. A. Jakobiec

T lymphocytes may be identified by two comparatively simple techniques: sheep erythrocyte (E) rosette formation and cytochemically demonstrable acid alpha-naphthyl acetate esterase (ANAE) activity. We tested the quantitative determination of T cells in 17 ocular lymphoid tumors as an indirect method for characterizing their clonality. Six lesions containing greater than 40% T cells (47% to 73%; mean, 62%) were shown to be polyclonal proliferations and were classified as pseudolymphomas by histologic criteria. Seven lesions containing less than 30% T cells (3% to 20%; mean, 10%) were shown to be monoclonal B-cell proliferations and were classified as malignant lymphomas by histologic criteria. Only two lesions containing between 30% and 40% T cells could not be unequivocally assigned to the monoclonal or polyclonal category solely based on the percentage of T cells. In the final two lesions, the tissue specimen was too small to allow a full panel of immunologic studies; both tumors showed a predominance of T cells consistent with their benign histologic features.