Acute Monocytic Leukaemia with Cutaneous Manifestation

Abstract

A 50‐year‐old Caucasian male presented with generalised skin rash. Gingival hyperplasia and hepatosplenomegaly were also noted. His laboratory data showed hemoglobin of 10.3 g/dL, white blood cell count of 203.6 K/uL and platelet count of 72 K/uL. Peripheral blood smears revealed that 67% of the white blood cells was monoblasts, 25% was promonocytes and atypical monocytes. Bone marrow aspirate smears showed that 97% of the nucleated cells were composed of monoblasts and promonocytes. Approximately 80% of the immature cells showed intense non‐specific butyrate esterase activity. The morphologic and cytochemical findings were compatible with a diagnosis of acute monocytic leukaemia. Skin biopsy taken from the left medial thigh revealed a Grenz zone and a dense infiltrate of atypical cells throughout the dermis. The cells were positive for KP1 (CD68) immunohistochemical stain. The findings were consistent with cutaneous manifestation of leukaemia (leukaemia cutis). The patient’s condition deteriorated rapidly despite chemotherapy and expired 10 days after initial presentation. Leukaemia cutis is more common in acute monoblastic/monocytic leukaemia (AMoL) than in other subtypes of leukaemia. Leukaemia gingival hyperplasia is another characteristic feature of AMoL. Dissemination to the skin is generally associated with a poor prognosis.