Primary cutaneous mucinous carcinoma (PCMC) is a rare low-grade malignant neoplasm derived from the eccrine glands. PCMC most commonly arises in the head and neck, with the eyelid being the most common site of origin. This case report describes a 51-year-old male with a painless, pigmented superficial nodular lesion over his right lower eyelid. The lesion was considered to be benign, and the initial treatment was simple excision with a 3-mm margin. However, histologic examination revealed the diagnosis of PCMC, and the patient underwent re-excision of the tumor site with an additional 3-mm margin from the initial scar. Histologic study of this second margin was free of any malignant cells. The patient experienced no postoperative complication or recurrence after 2 years. In our case, the skin lesion had benign morphologic findings and was strongly suspected to be a benign mass. Physicians should be aware of this tumor and be able to differentiate it from benign cystic or solid eyelid lesions.