Urachal mucinous tumor of uncertain malignant potential: a case report.

Urachal mucinous tumor of uncertain malignant potential is very rare and is characterized by a multilocular cyst showing the proliferation of atypical mucin-secreting cells without stromal invasion. As in ovarian and appendiceal borderline tumors, it represents a transitional stage of mucinous carcinogenesis in the urachus. In addition, this tumor may recur locally and develop into pseudomyxoma peritonei. Due to its scarcity and diagnostic challenges, we report a mucinous tumor of uncertain malignant potential arising in the urachus.