CD8A and thyroid gland undifferentiated (anaplastic) carcinoma: According to their analysis, there are two types of malignant neoplasms that have a high density of tumor-infiltrating CD8 positive T-lymphocytes: on the one hand, aggressive tumors such as anaplastic thyroid cancer, and on the other hand, tumors that are known to respond to immunotherapy, such as malignant melanoma or clear cell renal cancer [20].