Successful treatment of histiocytic sarcoma with induction chemotherapy consisting of dose-escalated CHOP plus etoposide and upfront consolidation auto-transplantation.

Histiocytic sarcoma (HS) is an extremely rare malignant neoplasm that often exhibits an aggressive clinical presentation. In this report, we describe the case of a 38-year-old female with advanced-stage HS who was found to have a subcutaneous tumor in the left calf and enlarged lymph nodes in the left inguinal and internal iliac regions. The subcutaneous tumor and inguinal nodes were resected operatively. Immunohistochemistry of the surgical specimens showed that the malignant cells stained positive for CD163, CD68, and related markers; a diagnosis of HS was established. Following the administration of induction chemotherapy consisting of dose-escalated CHOP plus etoposide, the remaining internal iliac tumors disappeared. At that point, high-dose chemotherapy with autologous stem cell transplantation was performed as consolidation treatment. The patient remains alive with no evidence of disease for 30 months post-treatment. This report provides valuable insight into the treatment of advanced HS.