Sarcomatoid carcinoma after radiotherapy for early-stage oral squamous cell carcinoma Case report

Rationale: Sarcomatoid carcinoma is a rare variant of squamous cell carcinoma (SCC) with poor prognosis. Previous radiation has been reported as one of the etiologic factors. Patient concerns: We describe a case of a 57-year-old man presented with a painless mass in the left supraclavicular area. Five years before, he was diagnosed with SCC in floor of mouth (FOM) and underwent radiotherapy (RT). Diagnoses: Sonography-guided biopsy on the supraclavicular lymph node revealed diffuse spindle cell proliferation with a focus of squamous differentiation. Local recurrence on primary site or distant metastasis was not obvious on both computed tomography (CT) of the neck and F-18-fluorodeoxyglucose positron emission tomography CT. The final diagnosis was confirmed as sarcomatoid carcinoma via surgery. Interventions: The patient underwent surgery including explorative resection of the mouth floor, excision of the submandibular gland, and modified radical neck dissection. Following surgery, the patient received adjuvant radiation therapy. Outcomes: There were no complications according to the surgery. Six months after adjuvant therapy, distant metastasis to liver was identified. The patient is currently undergoing palliative chemotherapy. Lessons: This may be the first reported case of sarcomatoid carcinoma arising from early-stage SCC in FOM that was previously treated with RT alone. When RT is performed as a single modality for oral SCC, even in an early stage, rigorous follow-up should be performed.