Clinical—An 84-year-old man presented with a 2-year history of worsening thrombocytopaenia and monocytosis with an associated painless plaque-like erythematous rash on his back and chest (Figure 1). Figure 1. Patient with erythematous rash Physical examination showed an erythematous malar rash sparing the nasolabial folds and involving the front and back of the upper chest and hepatosplenomegaly with no appreciable lymphadenopathy. A biopsy taken from the upper back demonstrated dermal interstitial infiltrate of mature histiocytic cells with occasional cells containing larger, atypical nuclei with conspicuous nucleoli. By immunohistochemistry these cells stained for CD68, confirming histiocytic differentiation and were negative for CD43/117/myeloperoxidase.A bone marrow biopsy and aspirate with flow cytometry showed the patient to have chronic myelomonocytic leukaemia-1 (CMML-1).Discussion—CMML is a myelodysplastic/myeloproliferative disorder characterised by monocytosis and associated anaemia and/or thrombocytopaenia. Skin infiltration by leukaemic cells, known as leukaemia cutis, is a frequent feature of acute monoblastic leukaemia but is rare in CMML.Lesions may be erythematous maculopapular rash, numerous widespread skin nodules, localised bullous lesions or a widespread itchy rash.