Non-small cell lung carcinoma metastasis to the anus.

A 70-year-old man presenting with a lung mass was investigated and treated with pneumonectomy for adenocarcinoma of the lung. He re-presented 3 months later with a large perianal abscess and mass. Subsequent investigations and biopsies showed disseminated metastases from the lung primary. Immunohistochemical staining confirmed the nature of the anal metastasis from the lung adenocarcinoma. Lung cancer is notorious for metastases, hence it is important to be aware of the uncommon modes of spread, which will help obtain early diagnosis and optimise treatment.