Cutaneous promyelocytic sarcoma at sites of vascular access and marrow aspiration. A characteristic localization of chloromas in acute promyelocytic leukemia?

Extramedullary disease (EMD) is a rare clinical event in acute promyelocytic leukemia (APL). Although the skin is involved in half of the reported EMD cases, the occurrence of cutaneous promyelocytic sarcoma (PS) has been described very rarely. We report here three cases of PS which have the peculiarity of appearing at sites of punctures for arterial and venous blood and marrow samples (sternal manubrium, antecubital fossa, wrist over the radial artery pulse, catheter insertion scar). At presentation, all patients had hyperleukocytosis and a morphologic diagnosis of microgranular acute promyelocytic leukemia variant confirmed at the genetic level by demonstration of the specific chromosomal translocation t(15;17). A BCR3 type PML/RARa transcript was documented in the two patients for whom diagnostic RT-PCR was available. Patients had morphologic bone marrow remission at the time the PS appeared. A predilection for the development of cutaneous PS at sites of previous vascular damage has been noted, but the pathogenesis remains largely unknown. A potential role for all-trans retinoic acid has been advocated, although one of the three patients in our series had received no ATRA. A review of the literature revealed six similar cases and hyperleukocytosis at diagnosis was a consistent finding in all of them. A careful physical examination of these particular sites in the follow-up of patients at risk, as well as cutaneous biopsy and laboratory examination of suspected lesions are strongly recommended.