Abstract
BACKGROUND: Papillary thyroid cancer (PTC) is the most common malignant tumor of the thyroid. However, the coexistence of PTC and sarcoma in one patient is rare. In this article, we report the case of a patient who presented with both PTC and undifferentiated pleomorphic sarcoma (UPS), which has not been previously reported in the online Medline database (PubMed). CASE SUMMARY: A 71-year-old man was admitted to our hospital for a mass on the right side of his neck for one month, which rapidly enlarged within 2 wk with distending pain. The patient was diagnosed with a thyroid malignancy by fine-needle aspiration and underwent total thyroidectomy and bilateral central lymph node dissection. Histology and immunohistochemistry revealed features of both PTC and UPS. The thyroid cancer 8 gene detection kit results showed BRAF and telomerase reverse transcriptase mutations. The disease progressed rapidly, and the patient died four months after surgery from extensive lung metastasis. CONCLUSION: Our report highlights the patient's pathological characteristics and related genetic mutations. Due to the rapid development and poor prognosis of cooccurring PTC and sarcoma, it is important for clinical physicians and pathologists to raise awareness of this type of tumor.