Leukemia cutis in acute promyelocytic leukemia: report of three cases after treatment with all-trans retinoic acid.

Acute promyelocytic leukemia (APL) is a distinct form of acute myelogenous leukemia characterized by an abundant number of abnormal progranulocytes, a severe coagulopathy and a distinct chromosomal abnormality t(15;17). Recently all-trans retinoic acid (ATRA) has been shown to induce complete remissions in APL. We report three patients with APL treated with ATRA, who at the time of relapse had leukemic infiltration of the skin (leukemia cutis), a manifestation which we had not seen previously in over 60 patients with APL treated with chemotherapy alone and has only rarely been reported in the literature. We hypothesize that ATRA treatment for APL may be associated with an increased incidence of extramedullary disease at the time of relapse, which may be mediated through an increase in expression of adhesion molecules. Careful observation for extramedullary relapses in patients treated with ATRA for APL will be needed to confirm our observation.