For a long time, hemophagocytic lymphohistiocytosis (HLH) was considered to be predominantly a childhood illness. However, in adult patients, this condition may arise as a result of underlying cancers, infections, or autoimmune disorders. Researchers hope to emphasize parallels and differences between juvenile and adult HLH, knowledge gaps, and current research topics in this paper. Malignancy is a more common cause of HLH in adulthood, accounting for approximately half of all cases. When compared to nonmalignant HLH, the prognosis is dismal. Adult patients had a poorer prognosis than juvenile ones, indicating that age and other concomitant diseases, unsurprisingly, impact the outcome of HLH. The incidence of mutations in HLH-causing genes in adults is greater than expected, with a higher frequency of uniallelic and hypomorphic mutations than in children.

Improving diagnostic criteria to allow for early diagnosis may help both children and adults. Because of the variety in triggering diseases, standardizing treatment techniques in adults will be more challenging, but a more uniform or algorithmic approach would likely be helpful. To comprehend the therapeutic and prognosis consequences of uniallelic and hypomorphic mutations in adults, more study into their function is required.