Gastric histiocytic sarcoma: a case report and literature review.

Histiocytic sarcoma is an exceptionally rare and highly aggressive neoplasm that exhibits the morphological and immunophenotypic hallmarks of mature histiocytes. It is characterized typically by extranodal presentation and a dismal clinical course, particularly in patients with disseminated disease. A history of hematolymphoid disorder can be identified in a subset of patients, suggesting transdifferentiation of a preexisting hematolymphoid neoplasm in its pathogenesis. A 38-year-old male patient presented for consultation following the detection of a gastric mass during a routine health examination. Subsequent multimodal evaluation, comprising abdominal computed tomography (CT), positron emission tomography-CT, and gastroscopy, indicated a high probability of malignancy, necessitating surgical resection. Comprehensive histopathological and immunohistochemical analyses confirmed the diagnosis of HS, and next-generation sequencing further corroborated this diagnosis. Despite surgical intervention, the patient succumbed to rapid disease progression within six months, further highlighting the intractable nature of this rare malignancy.