Differential diagnosis

• Infection of remnants of the allantois
• Infection of remnants of the omphalomesenteric (vitelline) duct
• Recurrent folliculitis
• Carbuncle
• Pilonidal cyst
• Infection due to navel piercing

The vitelline (omphalomesenteric) duct is a tubular embryonic structure that connects the midgut (middle part of the developing gut) with the yolk sac. Obliteration of the vitelline duct is usually completed by the 10th week of gestation. Failure of this physiologic process may lead to various abnormalities (Meckel's diverticulum, vitelline cyst or fistula).

The allantois connects the urogenital sinus with the umbilicus in embryonic life. Normally, the allantois is obliterated during embryological development and the structure left is called urachus. Incomplete obliteration can occur and according to its position is leading to patent urachus, urachal cyst, urachal sinus, or vesico-urachal diverticulum.

Diagnosis
Pyourachal cyst. An ultrasound of the umbilical area was performed, which suggested the diagnosis. Computed tomography scanning is especially helpful in patients in whom a malignancy of the urachal remnant is suspected.

Treatment
The patient was surgically managed with complete excision of the infected cyst together with the urachal remnant. In addition, treatment with intravenous ampicillin/sulbactam 1/0.5 gr every 6 hours was given for 5 days. During the 12 months of follow up of the patient, no recurrence was noted.

Teaching points

• Urachal cysts comprise 38% of all urachal abnormalities. (1)
• It seems that, umbilical manifestations such as umbilical discharge, umbilical mass, abdominal or periumbilical pain are predominant in patients younger than 30 years old, while bladder manifestations such as dysuria are more common among older patients. (2)
• Clinical signs of urachal cysts are more intense if they are complicated with infection, lithiasis, intestinal occlusion, hemorrhage into the cyst or malignant degeneration.
• Intraperitoneal rupture of a suppurative cyst and subsequently acute peritonitis is the most dangerous of all infectious complications associated with urachal abnormalities. (3)
• Staphylococcus aureus is the most commonly isolated microorganism from an infected urachal cyst. (4)
• Adenocarcinoma may arise from an urachal cyst. This is a rare complication representing about 0,01% of all adult carcinomas and 0,17 - 0,34% of all bladder neoplasms. (5)
• Urachal abnormalities may be a cause of urinary tract infections, which frequently are recurrent. This is explained by the fact that remnants of the allantois may be directly communicating with the bladder. (6)

References

1. Flanagan DA, Mellinger JD. Urachal-sigmoid fistula in an adult male. Am Surg 1998;64:762-3.
2. Yagishita H, Nagayama T, Zean Z et al. A case of asymptomatic urachal cyst in autopsy - Histopathological study of urachal cyst and review of the literature of 99 cases duting a 10 year period in Japan. Hinyokita Kiyo 2001;47:849-52.
3. Ohgaki M, Higuchi A, Chou H, et al. Acute peritonitis caused by intraperitoneal rupture of an infected urachal cyst: report of a case. Surg Today 2003;33:75-7.
4. Cilento BG, Bauer SB, Retik AB, Peters CA, Atala A. Urachal anomalies: defining the best diagnostic modality. Urology 1998;52:120-2.
5. Bianchi A, Toia G, Rovellini P, et al. Complicated urachal cyst: a difficult differential diagnosis. Arch Ital Urol Androl 1997;69:127-31.
6. Cappele O, Planet M, Pfister C, Navarra S, Grise P. Recurrent febrile infections of the urinary tract and diverticulum of the urachus. Prog Urol 1998;8:1043-6.

Acknowledgment

1. This case was prepared by Sofia K. Kasiakou, MD.
2. A full review of the literature regarding recurrent omphalitis in adults was published by our group in the Scandinavian Journal of Gastroenterology (Kasiakou SK, Rafailidis PI, Rosmarakis ES, Falagas ME. Recurrent omphalitis in the adults. Scandinavian Journal of Gastroenterology,2004;39:1021-1024).