Retroperitoneal Bulky Histiocytic Sarcoma Successfully Treated with Induction Chemotherapy Followed by Curative Surgery.

Histiocytic sarcoma (HS) is a rare hematopoietic neoplasm. We report a patient with HS treated with induction chemotherapy followed by curative surgery. A 50-year-old man was referred to our hospital because of a retroperitoneal tumor. A computed tomography scan revealed a bulky retroperitoneal mass, infiltrating the surrounding organ. An excisional biopsy confirmed the diagnosis of HS. The tumor shrunk after multidrug chemotherapy. However, positron emission tomography showed uptake of fludeoxyglucose in the residual tumor. He underwent right nephrectomy to remove the tumor. Pathological examination showed complete response. Surgery combined with induction chemotherapy may be an effective way to manage HS.