Aleukemia cutis: Clinicopathological and molecular investigation of two cases.

We describe two cases of acute myeloid leukemia (AML) who presented with cutaneous manifestations. Leukemia cutis (LC) is the cutaneous presentation of any type of leukemia and occurs in 10% to 15% of patients with AML, but cutaneous infiltration of AML rarely precedes the involvement of the bone marrow or peripheral blood and is called "aleukemia cutis." Our first case presented with facial skin thickening, a manifestation which is known as lionization and his initial clinical diagnosis was nonspecific allergic reaction. Our second case presented with urticaria-like lesions with the initial clinical and histomorphologic diagnoses of leukocytoclastic vasculitis. Histopathologic examination of skin biopsy specimens in both patients showed diffuse infiltration of the dermis with a monotonous population of intermediate-sized mononuclear cells by open chromatin and promonocytic features. Bone marrow aspiration leukocyte karyotyping showed normal cytogenetics, and molecular investigation revealed mutations of NPM1 and FLT3 genes. Somatic CEBPA gene mutation was negative in both patients. LC as the first manifestation of leukemia is very rare and could result in delayed diagnosis and affect patient prognosis.