Histiocytic sarcoma involving multiple abdominal sites: A rare case with KRAS mutation and response to ICE chemotherapy.

Histiocytic sarcoma (HS) is a rare and aggressive malignant neoplasm from histiocytic cells. This case report describes a 52-year-old male with HS involving multiple abdominal sites, diagnosed through imaging, histopathology, and immunohistochemical analysis, which identified a KRAS mutation. The patient underwent surgical resection followed by 6 cycles of ICE chemotherapy, resulting in significant clinical improvement and reduction of tumor burden. This case highlights the clinical presentation, diagnostic challenges, and potential treatment approach for this rare malignancy.