Skin infiltration in acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is a type of acute leukemia showing unique clinical, morphological and cytogenetic features. A skin infiltration by APL cells is an extremely rare occasion, but there have been several case reports of leukemia cutis in APL, in which all-trans retinoic acid (ATRA) may have induced the skin infiltration. However, no immunohistochemical analyses of the APL cells in the skin have been done to date. A 30-year-old woman with APL developed multiple reddish purple nodules on the extremities in her second complete remission. Histological findings revealed a dense infiltration of medium to large atypical cells, which were positive for myeloperoxidase, throughout the dermis. Despite the conventional chemotherapy and ATRA therapy she died from disseminated intravascular coagulation during her third relapse. Leukemic cells in the peripheral blood before the treatment with ATRA revealed CD3-/CD4-/CD5-/CD7-/CD8-/CD10-/CD13++/CD14-/CD19 -/ CD20-/CD33++/CD38++/CD41-/Ia-, but they expressed CD3-/CD4-/CD5-/CD7++/ CD8-/CD10-/CD13++/CD14-/CD19-/CD20-/CD33++ /CD38++/CD41+/Ia+ after the treatment. We suggest that the alternation of the surface molecules on the tumor cells is closely associated with the skin infiltration of APL cells.