Papular exanthem discloses acute myeloid leukaemia: interphase fluorescence in situ hybridization revealed deletion of p53 and gain at 8q22/8q24/Tel8q without trisomy 8.

We describe a 79-year-old patient who presented with fatigue, weight loss, pancytopenia and a papular exanthem. Previous attempts to taking bone-marrow biopsies had resulted in a 'dry tap', with no material collected, suggesting idiopathic myelofibrosis. Histological examination of skin biopsies showed dermal infiltration of monocytoid cells, resulting in a diagnosis of acute myeloid leukaemia (French-American-British M5 morphology) with leukaemia cutis (LC). Numerous abnormalities of chromosome 8 (trisomy or tetrasomy) have been identified in association with LC. We performed fluorescent in situ analysis on cutaneous tissue using directly labelled probes for various gene loci often involved in patients with AML; these tests showed deletion of p53 and excluded trisomy 8. However, application of probes for AML/ETO, MYC and telomere 8q revealed a gain at 8q22/8q24/8q telomere in a significant number of infiltrating cells. We hypothesize that a partial gain at 8q rather than trisomy of the whole chromosome 8 exhibits an association with LC in AML.