Although some authors have stated that UC with OGCs of the pancreas is apt to present as a large mass with a slow metastatic spread and a much better prognosis than ordinary carcinoma [14,15], the prognosis of UC with OGCs of the pancreas originating in a MCN and indeterminate mucin-producing cystic neoplasm remains unclear due to the small number of reported cases and short follow-up periods. Here, MUC5AC is linked to carcinoma.