An Atypical Presentation of a Non-neural Granular Cell Tumor.

Non-neural granular cell tumors (NNGCTs) represent a rare variant of granular cell tumors that lack S100 expression and do not demonstrate nerve-sheath differentiation, distinguishing them from conventional granular cell tumors (CGCTs), which are typically S100-positive and of Schwann cell origin. This report describes the case of a 46-year-old male presenting with a soft tissue mass arising from the right maxillary alveolar ridge. A hemimaxillectomy was performed, and the mass was sectioned to reveal light tan fibrous tissue grossly involving the underlying bone. The mass was composed of large neoplastic polygonal cells with granular cytoplasm that showed mild nuclear atypia and a low mitotic count. Immunohistochemical staining showed that the cells were positive for CD68 and CD45 expression but were negative for S100. The final diagnosis was reported as NNGCT. The prognosis, genetic alterations, and cellular origins of these tumors remain poorly understood. The findings included in this report will hopefully inform future investigations into the nature of NNGCTs and ultimately lead to improved treatment outcomes.