[Crosti's reticulosis. Report on three cases, one with ultrastructural study (author's transl)].

Crosti's reticulosis is defined as a peculiar form of well-circumscribed, slow developing lymphomas in adults, with a malignant histological picture. Three cases with typical dorsal localisation according to Crosti's first description are reported and the cardinal features of this type of tumour are recalled. One observation includes an ultrastructural study which confirms the malignant nature of histiocytes in this disease. Localisation in back seems not to be exclusive and a study of 32 cases of the literature about other localised cutaneous reticulum cell lymphomas show them similar to Crosti's reticulosis-which authorizes their classification, as was proposed by Thiers in a single group of slow developing circumscribed reticuloses.