Immunological, cytochemical and ultrastructural studies in lymphomatoid papulosis.

In lymphomatoid papulosis two histological types can be distinguished, i.e. type A and type B. In the present study various immunological, enzyme-histochemical and ultrastructural techniques were used to investigate the cellular infiltrate in both types of lymphomatoid papulosis. The type A lesions showed a predominance of large atypical cells, relatively few T cells and few or no Langerhans or related cells, as defined by a positive staining for OKT6 and NA I/34 antisera. The immunological, cytochemical and ultrastructural characteristics of these large atypical cells resembled those of the Langerhans cell/interdigitating reticulum cell series. The morphology and marker profile of these large cells resembled those of Reed-Sternberg cells, which suggests a relationship between lymphomatoid papulosis type A and Hodgkin's disease. The type B lesions showed a predominance of small, medium-sized and large cerebriform mononuclear cells with the phenotype of activated T helper cells, and numerous Langerhans and/or related cells. Their cellular composition was similar to that observed in the early stages of mycosis fungoides.