Leukemia cutis in acute myelomonocytic leukemia. Preferential localization in a recent Hickman catheter scar

We describe a patient with myelomonocytic leukemia who demonstrated striking leukemic infiltration in the scar of a recent Hickman catheter placement. This cutaneous involvement occurred initially without signs of systemic relapse. A comparative review of leukemic cell physiology provides several possible reasons for this extramedullary infiltration, including the greater functional maturity, deformability, adhesiveness, and ability to cluster of myelomonocytic and monocytic leukemia cells relative to other leukemias. A careful cutaneous examination, with particular attention to recent scars, may provide the only evidence of relapse in adult leukemia.