BI19 A rare association of acute myeloid leukaemia with pityriasis rotunda

Abstract We report a rare association of pityriasis rotunda, an uncommon dermatosis associated with acute myeloid leukaemia. A previously healthy 49-year-old man initially presented to his general practitioner with an asymptomatic scaly, circular, hyperpigmented singular patch on his back. He also reported a 1-week history of worsening fatigue and reduced exercise tolerance. Additional symptoms included reduced appetite and nausea. Initial investigations revealed severe anaemia (haemoglobin 45 g L−1), leucocytosis (white cell count 31.2 × 109 cells L−1) and a normal platelet count (221 × 109 cells L−1). A blood film demonstrated left-shifted neutrophils, occasional hypogranular neutrophils, and a population of blasts. The differential count identified blasts at 5.3 × 109 cells L−1, with a total white cell count of 33.3 × 109 cells L−1. A bone marrow biopsy was performed; the initial aspirate was aparticulate, showing 15% blasts on immunophenotyping. A subsequent particulate bone marrow aspirate revealed 22% blasts on morphology, with dysplasia in the megakaryocyte and granulopoietic cell lines. A diagnostic punch biopsy of the skin lesions was undertaken, demonstrating minimal hyperkeratosis. The underlying dermis showed mild chronic inflammation with a perivascular distribution. No leukaemic infiltration was evident, either morphologically or with the aid of immunocytochemistry. The patient was started on chemotherapy with cytarabine and daunorubicin, achieving complete remission. Six months after chemotherapy, the pityriasis rotunda had almost completely resolved. Pityriasis rotunda, a disorder of keratinization, is a rare diagnosis that can be associated with malignancies, including haematological and hepatocellular cancers (Suzuki Y, Aoshima M, Fujiyama T et al. Pityriasis rotunda associated with acute myeloid leukemia. J Dermatol 2018; 45: 105–6). This case underscores the importance of thoroughly investigating patients presenting with a constellation of systemic symptoms, as well as such dermatological findings, to rule out underlying malignancies.