Multiple brain lesions in a patient with relapsed hairy cell leukemia: a case report and review of the literature.

Cerebral lesions are rare in hairy cell leukemia (HCL), and its incidence remains to be determined. Identifying the cause can be challenging. In this report, we present a case of brain lesions occurring several years after diagnosis. A 76-year-old male patient presented to the Emergency Department with confusion. He had been diagnosed with HCL in 1999 and had received five lines of treatment. Cerebral imaging revealed multiple nodular lesions, with edema and a hemorrhagic appearance. Cerebrospinal fluid tests were negative. The tumor origin was retained due to concomitant relapse (blood, lymph nodes). Despite the partial efficacy of rituximab-cladribine treatment, the patient died of pneumonia. A review of the literature (PubMed, CrossRef, Google Scholar) identified seventeen cases between 1966 and 2024, with a median age of 59 years (33-80). Cladribine, with or without rituximab, was the most widely prescribed treatment regimen with a complete response rate of 57%. Four (23.5%) patients died (two from infection, one from gastrointestinal bleeding and one from an unknown cause). These atypical presentations suggest that brain imaging and advanced biological investigations should be performed to guide management.