demonstrated that immunofluorescence (IF) analysis of 53BP1 expression in cases other than BRAFV600E mutant PTC may be an excellent adjunctive technique for distinguishing whether a well-formed TFI in the cervical lymph nodes is metastatic carcinoma or ectopic thyroid tissue (ETT) by comparing the mutation analysis of primary thyroid cancer (7). The gene discussed is TP53BP1; the disease is thyroid gland carcinoma.