Squamous cell carcinoma of the nail unit (SCCNU) is a relatively uncommon tumor with a low rate of metastasis. SCCNU presents with nonspecific symptoms and signs, it is frequently misdiagnosed by dermatologists or surgeons. We report a patient with right-hand ring subungual squamous cell carcinoma who received inappropriate treatment due to a long-term misdiagnosis following trauma. This patient had been treated with acitretin combined with cefaclor, and a certain curative effect was seen, but finally, wide local excision was performed.