Hematopoietic Stem Cell Transplantation for the Management of Histiocytic Sarcoma: A Case Report and Systematic Review.

INTRODUCTION

Histiocytic sarcoma (HS) is a rare, aggressive hematolymphoid malignancy, accounting for <1% of cases, and no standard treatment exists. Management typically includes surgery, chemotherapy, radiotherapy, and immunotherapy. This systematic review and case report describe the clinical features, treatments, and outcomes of adult HS, with emphasis on stem cell transplantation in refractory disease.

METHODS

Following PRISMA guidelines, PubMed, Embase, and Cochrane databases were searched from inception to September 2025. Original studies involving adults (≥18 years) with confirmed HS were included. The extracted data included demographics, presentation, disease characteristics, diagnostic criteria, immunohistochemistry, treatments, follow-up, and outcomes.

RESULTS

Ninety-nine studies involving 185 patients were included. The median age was 55 years (range, 18-82 years). CHOP was the most frequently used chemotherapy regimen, followed by ICE; other regimens included HIPEC, DHAP, and AEVD. The median follow-up was 12 months (range, 0.5-144). Immunotherapy (eg, nivolumab and pembrolizumab) has demonstrated potential benefit in PD-L1-positive cases. Surgery (± radiotherapy) was performed in 64 patients with primarily unifocal disease, and favorable outcomes were achieved in approximately half of them. Ten patients underwent stem cell transplantation (5 allogeneic and 5 autologous), and 60% achieved remission in each group. We report a case of a 33-year-old man with refractory systemic HS who achieved durable remission (>1 year) following allogeneic haploidentical peripheral blood stem cell transplantation after failure of multiple chemotherapy regimens.

CONCLUSION

HS exhibits heterogeneous and aggressive behaviors that require individualized management. Allogeneic hematopoietic stem cell transplantation may be a viable option for treating refractory diseases.