Recurrent clear cell carcinoma of the tongue base with high grade transformation in a pregnant patient

Clear cell carcinoma is typically a low-grade salivary neoplasm with nests and trabecula of clear cells in hyalinized and desmoplastic stroma. Clear cell carcinoma has an EWSR1-ATF1 fusion and a good prognosis. We report on a 40-year-old woman with a tongue base clear cell carcinoma, for which she underwent transoral robotic resection, right neck dissection and adjuvant radiotherapy. The neoplastic cells were glycogen-rich and immunophenotypically of squamous lineage. There was brisk mitotic activity, focal comedo-like necrosis and bizarre malignant multinucleated cells. A fluorescent in situ hybridization was positive for EWSR1 rearrangement (22q12), thus confirming clear cell carcinoma. Four ipsilateral level II and III lymph nodes as well as a retropharyngeal lymph node were involved. While a presurgical pregnancy test had been negative, a repeat test after surgery was positive and the patient subsequently underwent shielded radiation therapy without chemotherapy. After two years of disease-free follow-up, the patient developed recurrent neck lymph node and lung metastases.