Primary Hepatic Histiocytic Sarcoma Mimicking Hepatocellular Carcinoma.

Primary hepatic histiocytic sarcoma (HS) is an exceptionally rare malignancy with nonspecific clinical and morphological features that often mimic other high-grade liver tumors making their diagnosis challenging. We report a 74-year-old man presenting with abdominal and back pain, fatigue, and a solitary right-lobe hepatic mass. Imaging suggested hepatocellular carcinoma, and the patient underwent right posterior sectionectomy. Histopathology revealed a high-grade neoplasm of discohesive large cells with eosinophilic cytoplasm and extensive necrosis. Immunohistochemistry confirmed HS. Given the extreme rarity of primary hepatic HS, we provide a focused literature review highlighting diagnostic challenges, immunophenotypic features, and current insights into the molecular landscape of this aggressive neoplasm.