Mature cystic teratoma(MCT)2 is the most prevalent neoplasm derived from germ cells in females; its progression to malignancy is infrequent. The coexistence of papillary thyroid carcinoma(PTC)3 and strumal carcinoid derived from MCT is exceptionally rare. To the best of our knowledge, only six cases of this condition have been reported to date, however, the molecular information and immune cell infiltration for the mixture has never been studied. We present a case of a patient exhibiting a combination of these two components in the MCT. The clinical and pathological characteristics of the patient are described in this report. For the first time, we demonstrated that NRAS codon 61 mutations were present in these two elements, and there was no significant difference between cancer-adjacent tissues and malignant tissues in immune cell infiltration. As a unique example of multiple malignant transformations in a single MCT, this case provides a basis for future investigations into MCTs.