Abstract
Cribriform morular thyroid carcinoma is a rare thyroid malignancy with uncertain histogenesis. It predominantly affects young women and is strongly associated with familial adenomatous polyposis. This paper reports a rare case of sporadic cribriform morular thyroid carcinoma in a female patient in her early 50s, with somatic genetic testing revealing a KMT2C mutation. She presented with a solitary lesion confined to the right thyroid lobe and had no family history of familial adenomatous polyposis. Colonoscopy and germline genetic testing revealed no abnormalities. This finding suggests a potential link between KMT2C mutations and sporadic cribriform morular thyroid carcinoma. The clinical and imaging manifestations of this malignancy lack specificity, and the final diagnosis depends on routine pathological examination and immunohistochemical analysis. This report indicates the need for the clinical investigation of family history and genetic testing, thus contributing to the clinical realization of standardized follow-up monitoring and management.