An enigmatic tale of macrophages in bone marrow causing inflammation of the brain: A case report on CNS HLH

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening immune disorder characterized by excessive inflammation and multiorgan involvement. Rarely, HLH can manifest with signs and symptoms isolated to the central nervous system (CNS). This case report highlights the unique clinical course of CNS-isolated HLH in a 19-year-old female who, despite a nine-year delay in diagnosis, achieved disease remission following a hematopoietic stem cell transplant (HSCT).

The patient initially presented at 9 years old with seizures, ataxia, and progressive cognitive decline. Over the next nine years, extensive diagnostic evaluations were performed, including neuroimaging, cerebrospinal fluid analysis, and genetic testing. Genetic testing identified a compound heterozygous mutation in the PRF1 gene, confirming a diagnosis of familial HLH (FHL). The patient underwent hematopoietic stem cell transplant (HSCT) from an HLA-matched unrelated donor. Despite significant complications, including multiple infections and renal failure, she achieved remission. Six years post-transplant, the patient exhibited stabilization of neurological function, cessation of seizures, and absence of active HLH.

This case underscores the importance of considering genetic testing in patients with unexplained CNS symptoms and atypical radiological findings. Timely HSCT, even in cases with delayed diagnosis, can lead to remission and improved quality of life.