To Transplant or Not to Transplant? Late-Onset Primary HLH in a Patient: A Case Report and Review of Literature.

Primary, or familial, hemophagocytic lymphohistiocytosis (P-HLH) is a rare inherited autosomal-recessive immune deficiency which generally manifests during infancy or early childhood. Recent literature suggests an increased number of reports of late-onset P-HLH, especially in association with infection and underlying malignancy. The authors describe a case of subcutaneous T-cell lymphoma in a 8-year-old child that was complicated by primary, perforin-deficient HLH. In contrast, we examined retrospective data for 19 cases of late-onset P-HLH with available treatment data and compared the results of conservative medical therapy with hematopoietic stem cell transplant (HSCT) postremission therapy. Our patient displayed compound heterozygous mutations in PRF1 that have not been described in the literature previously: allele 1 [c.786_801del(p.Gln263fs)] and allele 2 [c.886T>C(p.Tyr296His)]. Of the 19 cases analyzed, 14 achieved remission. Postremission, 7 of 14 (50%) received HSCT and were reported alive at a median time of 24 months, 5 of 14 (36%) received medical therapy and were reported alive at a median time of 24 months, and 2 of 14 (14%) received medical therapy and died at a median of 73 months postremission. Our retrospective literature review suggests that some patients can survive late-onset, perforin-deficient, P-HLH without the potential lifelong risks of HSCT when in the first remission.