Patterns of cutaneous lymphomas. Histological, enzyme cytochemical, and immunological typing of lymphoreticular proliferations in the skin.

During recent years there has been much progress in interpreting the histo- and cytomorphology of lymphoreticular proliferations by means of enzyme cytochemical (cell typing by hydrolytic enzymes) and immunological (B- and T-cell differentiation using surface markers and functional tests) methods. Applying these methods in skin biopsies from 101 patients clinically suspected of having cutaneous lymphomas, patterns of lymphoreticular infiltrations in the skin have been elaborated. Based primarily on the 'Kiel' classification, low-grade and high-grade malignant lymphomas, pseudolymphomas and 'histiocytic lymphomas' can be differentiated in the skin; however, there still remain some hitherto unclassifiable lymphoreticular proliferations. In the low-grade malignant lymphomas of the skin, mycosis fungoides, Sézary's syndrome and Pagetoid reticulosis histologically display a pattern which is typical for T-cell infiltrations in the skin, whereas most of the 'malignant reticuloses', including immunocytoma, show a B-cell pattern. Erythrocyte antibody complement rosette fixation on cryostat sections is positive only in cutaneous pseudolymphomas whereas no fixation is seen in malignant B-cell lymphomas of the skin.