Proliferation kinetics of the dermal infiltrate in cutaneous malignant lymphomas

To obtain information about the role of local proliferation in the pathogenesis of dermal infiltrate in malignant cutaneous lymphomas, we determined the percentage of 3H-thymidine-labeled infiltrating cells (3H-index). A linear correlation was found between proliferative activity and clinical stage in mycosis fungoides, i.e., the 3H-index is moderately elevated in stage I and high in stage III. The 3H-index is within normal range in dermal infiltrate of Sézary syndrome, diffuse lymphocytic lymphoma, as well as in lymphocytoma benign cutis. In parapsoriasis en plaques two groups can be distinguished: in the small-plaque variant (chronic superficial dermatitis) the 3H-index is low, whereas the large-plaque variant (prereticulotic poikiloderma) shows strong proliferative activity. Thus, determination of proliferative activity seems to give new insights into the pathogenesis of dermal infiltrate in cutaneous lymphomas.