Uncommon Presentation of Ossifying Fibromyxoid Tumor (OFMT) in the Cheek: A Unique Case in the Head and Neck Soft Tissue

Summary: Ossifying fibromyxoid tumors (OFMTs) represent infrequent neoplasms with borderline malignancy and an elusive origin. Their common manifestation involves nonspecific pain in the extremities. Occurrence in the subcutis and skeletal muscle of the extremities is frequent with a common manifestation of nonspecific pain. Occurrence in the soft tissues of the head and neck is infrequent, constituting 10-15% of cases and presenting diagnostic challenges. The scarcity of this lesion and its unconventional characteristics may lead to diagnostic delays and complexities in patient care. Most cases harbor PHF1 gene fusion. Within this context, we present a distinctive instance of an OFMT of the soft tissue of the cheek in a 51-year-old male who presented with a 2.2 cm painless cheek mass lateral to the angle of the mouth. A surgical excision was performed. Microscopic examination revealed a well-circumscribed tumor surrounded by an incomplete shell of lamellar bone. The tumor cells exhibited a monotonous ovoid morphology and were embedded within a fibromyxoid stroma. No significant nuclear atypia was observed, and only rare mitotic figures were identified. Tumor cells showed positive staining for vimentin, focal positive staining for S100, and negative staining for SMA and pan-CK. Desmin staining was positive in scattered cells.