TTF1 and neoplasm: The expression of P63 in PLGA/PAC was focal and scattered, indicating that the tumor cells had no squamous or myoepithelial differentiation.[13] PLGA/PAC is negative for TTF-1, napsin-A, and neuroendocrine markers, which can help distinguish it from lung adenocarcinoma and neuroendocrine tumors.[13,14] Lung metastatic PLGA/PAC and other salivary gland tumors should be ruled out based on detailed medical history and clinical examinations.