Carcinoma of the urachus.

Characteristic roentgenographic and anatomical features of a mucinous adenocarcinoma of the urachus were observed in two patients. Both presented with a midline anterior abdominal mass in the supravesicular area. The tumor contained fine stippled calcification in one case. The cystogram demonstrated an irregular filling defect in the bladder dome in the other case. Ultrasonographic examination in one case was helpful in delineating the nature, size, and location of the mass in detail.