Pralatrexate induces skin erosions limited to areas affected by ATLL. (A) ATLL skin lesions with confluent erythematous papules of the dorsal hands with areas of sparing over knuckles (*). Pompholyx-like lesions on digits. Pictures were taken 3 days after the first dose of pralatrexate was given. (B) Skin erosions within affected areas 6 days after the first dose of pralatrexate was administered. (C) Resolution of rash with postinflammatory hyperpigmentation 3 months later. (D) Higher magnification of skin erosions (arrow) on the right leg 6 days after the first dose of pralatrexate. (E) In situ hybridization for HTLV-1 shows positive signal within atypical lymphocytes in the epidermis (bold arrow), whereas red counterstain is observed in dermal fibroblast (→; original magnification ×40). (F) Immunohistochemistry for HTLV-1 shows positive signal in atypical lymphocytes in Pautrier microabscesses (; original magnification ×40).