The quantitative morphometric analysis of the skin lesions of patients affected by nonulcerated or atypical cutaneous leishmaniasis showed that the cellular density (mean ± standard error) of CD4+ T lymphocytes was 296.60 ± 53.47, that of FoxP3+ cells was 168.40 ± 28.71, that of TGF-β+ cells was 78.63 ± 16.54, and that of IL-10+ cells was 63.72 ± 9.70 cells/mm2. This evidence concerns the gene IL10 and cutaneous leishmaniasis.