Leukaemic arthritis in a patient with monocytic leukaemia and osteoarthritis

Leukaemic arthritis (LA) is a rare complication in adult leukaemia, typically involving large joints and sometimes even preceding the diagnosis of leukaemia. A strong association with monocytic leukaemia and pre-existing joint disease, such as osteoarthritis and rheumatoid arthritis, has been observed. Our case describes a patient with newly diagnosed acute myeloid leukaemia of monocytic differentiation, central nervous system involvement and LA of the right ankle. Often mistaken for rheumatological disease, we aim to highlight the importance of recognising LA as a possible differential in a patient with joint pain and pre-existing risk factors. The absence of timely intervention may result in irreversible joint injury while systemic chemotherapy can lead to dramatic joint pain improvement.