Perianal metastasis of non-small cell lung cancer.

We herein present the case of a 36-year-old woman who developed perianal metastasis of non-small cell lung cancer that was diagnosed based on the presence of symptoms mimicking a hemorrhoid. The patient initially underwent radiotherapy for a left superior sulcus tumor, then subsequently complained of a perianal mass that had prolapsed and bled. The tumor was removed via resection. Histologically, the mass was diagnosed as poorly differentiated carcinoma and considered to be a metastatic lesion arising from the primary lung cancer.