A Rare Solitary Fibrous Tumor Localized in the Upper Lip: A Case Report.

Solitary fibrous tumor (SFT) is an uncommon mesenchymal neoplasm, rarely localized to the head and neck region. Due to its diverse morphological and histological characteristics, SFT may be misdiagnosed as other soft tissue sarcomas. This case report describes an atypical presentation of SFT involving the upper lip in a 75-year-old man. The only non-specific clinical symptom was localized swelling. An intraoral examination revealed a well-defined, exophytic soft lesion. Magnetic resonance imaging (MRI) revealed a heterogeneous, lobulated lesion with well-defined margins and marked contrast enhancement. The histopathological evaluation demonstrated a proliferation of spindle cells with low mitotic activity within the dense fibrous stroma. Immunohistochemical (IHC) analysis confirmed the diagnosis of benign SFT, showing strong positivity for STAT6, CD34, and Ki-67 markers. Surgical excision of the mass and subsequent histopathological examination of the resected specimen corroborated the initial diagnosis. The patient underwent a follow-up evaluation six months postoperatively, presenting with a fully healed surgical site and no signs of recurrence.