TTF1 and thyroid tumor: Given the patient’s acute onset of symptoms following PET and the need for tracheostomy, an excisional thyroid biopsy was performed at the time of tracheostomy and aided in subsequent diagnosis. Immunocytochemistry with various antibodies as a panel, including TTF-1, PAX8, CK7, and CK20, is helpful in the confirmation of a secondary thyroid neoplasm diagnosis as observed in this case [2].