Question 196

Question:

A 6-year-old boy has a large intra-abdominal mass in the midline just above the symphysis pubis. During an operation, a cystic mass is found attached to the umbilicus and to the apex of the bladder. Which of the following is the most likely diagnosis?

Correct Answer: E.  Urachal cyst

The urachus is a connection between the dome of the bladder and the umbilicus that obliterates during development. A urachal cyst (Answer E) is usually located in between the obliterated ends of this developmental duct. A hydrocele (Answer A) is a benign collection of peritoneal or scrotal fluid in the scrotum. It is usually due to patent processus vaginalis or scrotal fluid imbalance. A meckel cyst (Answer B), aka duplication cyst, often contains ectopic gastric mucosa. It is most often located in the ileum, duodenum or stomach. A Meckel’s diverticulum (Answer C) is an intestinal outpouching that usually occurs in the ileum. It occurs when the vitelline duct, which connects the primary midgut and the yolk sac, fails to obliterate. During the 6th week of development, the midgut herniates through the umbilical cord. An omphalocele (Answer D) occurs during week 12 when this hernation fails to retract, leaving an amnion-covered sac protruding through the umbilicus.