Clinical case: Urachal cyst
Ureter, utrehtra, urachus - all of them somehow related to the urinary bladder. At some point you must have wondered which is which, and which one is the most important? Most of the students would instantly think that it is the ureter, since among these three, most of the cited pathology is related to it.
That is why this clinical case will present a woman with an urachal cyst, providing you with an answer that every part of human body is equally important, specially from the aspect of disease.
Urachus |
In embryo -> fibrous connection between urinary bladder and umbilicus In adults -> fibrous cord called median umbilical ligament that extends from urinary bladder to umbilicus |
Differential diagnosis for an urachal cyst |
Vitelline duct anomailes Appendicitis Granulomatous inflammations Granulation tissue from umbilical stump |
Pathological confirmation |
Urachal cyst - lined with urothelium (transitional epithelium) Mesenteric cyst - lined with mesothelium |
Potential complications | Infection, bleeding, enlargement, intraperitoneal rupture, intestinal fistula, intestinal obstruction, lithiasis, tumor, macroscopic hematuria, dysuria |
After reviewing this case you should be able to describe the following:
- The development and normal progression of the urachus including its remnant in the adult.
- The differential diagnosis of a urachal cyst.
- How a pathologist would be able to determine that the extirpated structure was derived from the urachus.
- The potential complications of a urachal cyst.
This article is based on a case report published in the Journal "Case Reports in Surgery" in 2015, by Caroline C. Jadlowiec, Beata E. Lobel, Namita Akolkar, Michael D. Bourque, Thomas J. Devers, and David W. McFadden.
Case description
A 17-year-old woman presented with periumbilical pain. A physical exam found a painful 5 cm mass in the umbilical region. All laboratory tests were within normal limits but ultrasound and CT exams showed a cystic mass at the location found in the physical exam (Figure 1).
Based on these findings, a mini-laparotomy was performed and a cystic mass was found that was connected to the ileal mesentery, but which was not connected to the urinary bladder or umbilicus (Figure 2).
After extirpation, the mass was described in the pathological report as a urachal cyst (Figure 3).
The patient recovered well from the surgery with no complications seen at a three- month follow-up exam.
Anatomical considerations
In the adult, the urachus is known as the median umbilical ligament, which is different than the medial umbilical ligaments (Figure 5). The right and left medial umbilical ligaments are the remnants of the right and left umbilical arteries. These arteries branch from the respective internal iliac arteries and bring oxygenated blood to the fetus during pregnancy. In the adult, umbilical arteries may remain patient as far as the bladder, with the remainder forming fibrous cords similar in appearance to the median umbilical ligament.
The unoxygenated blood from the fetus returns to maternal circulation through the umbilical vein to the portal vein. The ligamentum teres of the liver runs within the falciform ligament and is the remnant of the umbilical vein, In this patient, the cyst was not connected to either the urinary bladder or umbilicus, but rather located at the ileal mesentery.
Explanation to objectives
Objectives
- The development and normal progression of the urachus including its remnant in the adult.
- The differential diagnosis of an urachal cyst.
- How a pathologist would be able to determine that the extirpated structure was derived from the urachus.
- The potential complications of an urachal cyst.
Urachus
The urachus is a fibrous embryonic connection between the urinary bladder and the umbilicus. It is the remnant of an earlier embryologic structure, the allantois. In the adult the urachus is known as the median umbilical ligament (Figure 5) a fibrous cord deep to the transversalis fascia, which remains connected to the bladder and the umbilicus.
Urachal cyst differential diagnosis
The differential diagnosis for an urachal cyst in an adult would include vitelline duct anomalies, appendicitis, granulomatous inflammations, and granulation tissue from the umbilical stump.
Pathological confirmation
Microscopic analysis of the cyst could make the diagnosis that this structure was a urachal rather than a mesenteric cyst (also would be attached to mesentery) because the lining cells of a urachal cyst are urothelium (transitional epithelium), as would be expected based on the embryological origin of this cyst (Figure 6). In contrast, mesenteric cysts would likely be lined by a mesothelium (simple cuboidal or squamous epithelium typical of mesenteric lining).
Potential complications
Urachal cysts are usually asymptomatic. However, complications may include infection, bleeding within the cyst, enlargement, intraperitoneal rupture, intestinal fistula, intestinal obstruction, lithiasis, and malignant degeneration. Furthermore, these cysts may be associated with urinary tract infection, macroscopic hematuria, or dysuria.
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