A case of primary lung cancer requiring differentiation from metastatic cervical cancer.

p16 has been used as a surrogate marker for human papillomavirus (HPV)-related tumours. However, it remains unclear whether p16 is also a potential marker for pulmonary tumours. Herein, we report the case of an 80-year-old woman with a history of papillary squamous cell carcinoma of the uterine cervix, presenting with a left pulmonary tumour. A bronchoscopic biopsy revealed squamous cell carcinoma with a papillary pattern, which did not rule out pulmonary metastasis from the cervix. Immunohistochemical staining revealed that the cervical tumour was positive for p16, whereas the pulmonary tumour was negative and was effectively diagnosed as primary pulmonary carcinoma.