Abstract: Infective dermatitis associated with HTLV-1 (IDH) is the main cutaneous marker of HTLV-1 infection. This disease occurs primarily in children and should be differentiated from other eczemas, especially from atopic dermatitis. The largest series of IDH are from Jamaica and Brazil. There are an estimated 15 to 20 million infected people in the world, and Brazil is one of the endemic regions. Studies suggest that IDH in children may be a marker for the development of T-cell leukemia/lymphoma (ATL) or myelopathy associated with HTLV-1/tropical spastic paraparesis (HAM / TSP) in adulthood.

A sixty-one year old white female was referred to the Dermatology Department to treat an ingrown nail in the inner corner of the left hallux. Examination of the entire nail unit showed the presence of xanthonychia in the outer corner besides thickening and increase in the transverse curvature of the nail plate. Dermoscopy and nuclear magnetic resonance of the free edge of the nail plate detected characteristic signs of onychomatricoma, a diagnosis that was later confirmed by anatomopathological exam.