Primary mucinous carcinoma of the skin: a case of metastasis after 10 years of disease-free interval.

Primary mucinous carcinoma of the skin (MCS) is a rare neoplasm. Clinically, it has a high local recurrence rate, but it is known to be a slow-growing benign tumor with a rare incidence of distant metastases. We present a case of primary MCS on the jaw that underwent tumor resection twice and was disease-free for 10 years after the second surgery. The patient had no evidence of local recurrence and distant metastasis until his 11th year follow-up. At that time, he was diagnosed with lung and bone metastasis and died 3 years after this. To our knowledge, this is the first case of MCS that presented with metastasis with more than 10-year disease-free interval. Since MCS is a slow-growing asymptomatic tumor, distant metastasis is difficult to diagnose without detailed radiological examination. We believe that computed tomography and resonance imaging should be performed for early diagnosis of metastasis even for cases with long-term disease-free interval, especially cases of local recurrence.