An 80-year-old male patient underwent partial resection of the tongue following chemoradiotherapy for his left-sided tongue squamous cell carcinoma （SCC） （T3N0M0）. A blood test 2 months after the operation showed a high SCC antigen level of 9.7ng/mL, but a systemic examination revealed no abnormal findings. Meanwhile, the patient complained of itchiness and dryness of the skin over the entire body, which eventually led to a diagnosis of asteatotic eczema being made upon examination by the Department of Dermatology of our hospital. After his dermatological symptoms had improved with treatment, his serum SCC antigen level normalized, and there were no findings of recurrence and metastasis or cancer in other organs. Therefore, the elevated SCC antigen level was deemed to be a false-positive reaction accompanying the cutaneous lesions. At around 1 year 6 months after surgery, the rash exacerbated again, and approximately 1 year 11 months later when the rash symptoms were the most severe, the SCC antigen level increased to 51.1ng/mL. Although SCC antigen is used as a tumor marker for oral squamous cell carcinoma, it should be kept in mind that it can be elevated in various diseases such as skin diseases.
