Progressive Sarcomatoid Acquisition in Oral Squamous Cell Carcinoma: The Epithelial-Mesenchymal Transition Landscape in a Long-Term Follow-Up Case

Spindle cell carcinoma (SpCC), also known as sarcomatoid carcinoma, is a rare and aggressive variant of squamous cell carcinoma (SCC) that contains a biphasic pattern, with conventional SCC and spindle cell components. We report the case of a 63-year-old female patient with a history of alcohol and tobacco use who was diagnosed in May 2018 with well-differentiated SCC of the tongue and treated with partial glossectomy, cervical lymphadenectomy, and adjuvant radiotherapy. In May 2023, the patient developed a recurrence in the right retromolar trigone, confirmed as moderately differentiated SCC and managed surgically with segmental mandibulectomy. Two years later, in May 2025, a rapidly enlarging lesion in the right floor of the mouth was diagnosed as SpCC. Histopathology revealed a sarcomatoid neoplasm lacking epithelial marker expression (AE1/AE3, EMA, p63, and CAM5.2) and positive for VIM, SMA, caldesmon, and calponin. Based on the patient’s oncologic history and immunohistochemical profile, a diagnosis of SpCC was established. This case highlights the potential for histological transformation and diagnostic challenges in long-term survivors of head and neck SpCC.