Oral histiocytic sarcoma: A case report and literature review.

Histiocytic sarcoma (HS) is a rare and aggressive malignancy derived from mature histiocytes, accounting for less than 1% of hematologic disorders. Clinically, HS varies from localized disease with a solitary mass to disseminated disease, often associated with other hematolymphoid neoplasms. Its aggressive nature results in poor outcomes, with a median survival of six months in disseminated cases. HS is exceedingly rare in the oral cavity, with only ten cases reported in the literature. Diagnosis is challenging due to significant histological overlap with other entities. This report describes a case of oral HS in a 62-year-old male presenting with painful and bleeding nodules on the mandibular alveolar ridge. A literature review including all cases of HS in the oral cavity was made. Histopathology revealed sheets of anaplastic neoplastic cells with marked nuclear pleomorphism and atypical mitotic figures. Immunohistochemistry confirmed histiocytic differentiation with CD163 and lysozyme positivity. Our review of oral HS cases showed a total of nine cases and highlighted variability in clinical presentation, anatomical site involvement, and diagnostic challenges. Morphologically and immunohistochemically, HS presents a diagnostic challenge and requires careful differentiation from other sarcomas, lymphomas, carcinomas, and melanoma. Despite the rarity of oral HS, documentation of such cases is critical for advancing diagnostic precision and clinical understanding.