Conselho Nacional de Desenvolvimento Científico e Tecnológico (http://www.cnpq.br/), grant number 409985/2016-3, received by AL and by the Fundação de Amparo a Pesquisa do Estado da Bahia (http://www.fapesb.ba.gov.br), grant number 4345/2012. This project has also received fundingfrom the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska Marie Curie grant agreement num 799850 (LF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Infective dermatitis associated with human T-cell lymphotropic virus type-1 (HTLV-1), (IDH), is a chronic eczema occurring in HTLV-1 infected children. Rare cases of adulthood IDH have been reported and no study until now aimed to compare juvenile and adulthood IDH. Methodology/Principal findings Twelve cases of adulthood IDH followed for a mean time of 7.5 years were analyzed according to clinicopathological and molecular aspects, comparing them to juvenile IDH cases. Diagnosis was based on the modified major criteria used for juvenile IDH. Proviral load (PVL) assessment was performed by real-time PCR technique. Adulthood IDH presented similar clinicopathological and molecular aspects compared to juvenile IDH. The morphology of lesions and areas of involvement were similar, except for the involvement of the ankles and inframammary folds in the adulthood form. HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) occurred in six adulthood IDH patients, with almost equal frequency. However, at least in two patients, HAM/TSP appeared prior to IDH, differently from what was observed in juvenile IDH. Conclusions/Significance Adulthood IDH is similar to juvenile IDH according to clinicopathological aspects and PVL levels. Therefore, the same modified major diagnostic criteria for juvenile IDH can be applied to both forms.