Life-threatening thrombotic events revealing systemic lupus erythematosus in a patient with chronic myelomonocytic leukaemia

mutations, and cytogenetic abnormalities (46 chromosomes with a long arm deletion of chromosome 16). In August 2024, she was hospitalized for worsening general condition and dyspnoea, revealing hyperleukocytosis (206 g/l), progressive monocytosis, medullary infiltration, and bilateral pericardial/pleural effusions. A positron emission tomography scan demonstrated bone marrow hypermetabolism and splenomegaly. Treatment with azacitidine and venetoclax was initiated, but weeks later, she developed ST elevation myocardial infarction, ischemic stroke, and deep vein thrombosis, requiring intensive care. Immunological testing showed high-titre antinuclear antibodies (1/1280), anti-Ro52, anti-Sm/RNP, and anti-U1 RNP and complement consumption, leading to a diagnosis of systemic lupus erythematosus (/American College of Rheumatology/ European League Against Rheumatism 2019 criteria). Hydroxychloroquine was started, followed by hydroxycarbamide, azacitidine, and ruxolitinib due to persistent hyperleukocytosis (peaking at 100 g/l), resulting in clinical and biological improvement. The patient underwent allogeneic stem cell transplantation in mid-March 2025. This case highlights the complex interplay between hematologic malignancies and autoimmune diseases, emphasizing the need for multidisciplinary management. LEARNING POINTS: There is a two-way relationship between hematologic malignancies and autoimmune diseases, where each can potentially initiate or exacerbate the other.Effective management requires close collaboration between haematologists, immunologists/rheumatologists, and intensive care specialists.