IgA vasculitis associated with chronic myelomonocytic leukemia.

IgA vasculitis is a predominantly pediatric autoimmune disease characterized by IgA deposit in small vessels. Chronic myelomonocytic leukemia (CMML) is a rare hematological malignancy classified within myelodysplastic syndromes. Here, we present a previously unrecognized case of CMML associated with IgA vasculitis. A 62-year-old woman presented with necrotic and infiltrated purpura and mild arthralgia, primarily affecting the knees and wrists, without gastrointestinal or kidney involvement. A comprehensive screening for other etiologies was unremarkable. Blood tests showed an increase of monocyte count and circulating monocyte phenotyping was consistent with CMML. Bone marrow analysis showed no blast cells or karyotypic abnormalities. Genetic testing identified an NRAS mutation. Autoantibody screening and viral serologies were negative. A skin biopsy revealed small-vessel vasculitis with IgA immune deposits. CMML can be associated with autoimmune diseases, such as polyarteritis nodosa and cutaneous leukocytoclastic vasculitis. However, this is the first report of IgA vasculitis occurring in the context of low risk CMML.