[Mycosis fungoides].

The classical characteristics of Myocsis Fungoides are discussed. 1) The clinical characteristics of the three forms: tumour from the start, erythrodermic and polymorphic forms of Alibert-Buzin. 2) Histological characteristics : dense dermal infiltrates or epidermotropic infiltration, or around a more or less malignant histiocytic reaction, there develops a host reaction, resembling a granuloma. During the course of the disease, one may observe lymphocyte depletion, whilst delayed hypersensitivity tests become negative. The various types of lymphadenopathy are analysed, the possibility of visceral lesions confirmed. However, knowledge of Sezary's syndrome makes his concept of the disease doubtful. A pathological picture similar to Mycosis Fungoides may be observed during Sezary's syndrome, with circulating giant cells. The presence of small Sezary cells, Lutzner-Flandrin variety, is common in the dermal infiltrate, and even more common in the lymph node visceral infiltrates of Mycosis Fungoides. Thus, one is led to the concept according to which the primary phenomenon is probably pathological proliferation of abnormal T lymphocytes (large and small Sezary cells), the histiocytic proliferation would then simply be a secondary reaction. This theory is then discussed.