A rare case of urachal adenocarcinoma arising in urachal cyst: clinical and radiological features

Clinical History

A 45-year-old female patient was referred to our hospital with a few months history of abdominal mass which was rounded and of hard consistence.
The patient reported that this mass was not painful and that it had become evident during an interrupted pregnancy (at the twenty-second week) for fetal anencephaly.

Imaging Findings

First abdomen ultrasound was performed which showed a capsuled lesion, hypoechoic as a fluid component, with a size of 4x5 cm. Solid hyperechoic areas at the anterior wall of the lesion were also documented.
Then MRI showed a lesion in the mesogastric region behind the navel, underneath the muscular plane, of 4x5 cm, with regular borders, hyperintense in T2 weighted images. It consisted mainly of fluid components, and the presence of a solid component adherent to the antero-superior wall of the lesion was confirmed.
Contrast gadolinium-enhanced sequences showed homogeneous enhancement in correspondence of the lesion’s solid component.
According to imaging features, suggestive for urachal disease, the patient underwent a surgical resection of the lesion and the histological result was urachal adenocarcinoma G1 arising in the urachal cyst.
Subsequent whole body CT to a proper staging of the disease showed no secondary lesions.
Evaluation by F18-FDG PET-CT revealed no hypermetabolic focus.

Discussion

The urachus is an embryologic remnant extending between the roof of the bladder and the umbilicus [1].
Urachus becomes completely obliterated shortly after birth, giving rise to the median umbilical ligament [2].
There are different types of urachal abnormalities: 1) patent urachus, in which the entire tubular structure fails to close (50%); 2) urachal cyst, in which both ends of the canal close leaving an open central portion (30%); 3) urachal sinus, which drains proximally into the umbilicus (15%); 4) diverticulum between bladder and urachus (3–5%); 5) alternating sinus, which can drain to bladder or umbilicus [3-4].
Although the urachal remnants are usually lined by transitional type epithelium, the presence of focal mucinous glandular metaplasia may provide a morphological basis for the development of intestinal-type mucinous neoplasms [5-6] and 85%–90% of urachal carcinomas are adenocarcinomas.
Adenocarcinomatous change in urachal cystic remnant, as in our case, accounts for 0.17-0.34% of all bladder cancers [5-7].
Haematuria is the most common symptom in about 90% of patients with urachal adenocarcinoma [8] but nonspecific symptoms such as dysuria or hypogastric complaints may be present [1].
Gore and associates described criteria to label urachal adenocarcinoma and distinguish it from bladder or metastatic process: 1) sharp demarcation between tumour and an intact, normal surface urothelium, 2) the absence of cystitis cystica or glandularis, and 3) tumour growth in the bladder dome or anterior wall. [6]
Radiological evaluation of suspected urachal disorders include radiography, cystogram, ultrasound (US), Computed tomography (CT) and magnetic resonance imaging (MRI). Because the urachus is located in the anterior abdominal wall and does not interfere with intestinal structures, CT and US are suited for demonstrating urachal anomalies. A midline soft tissue mass above the bladder on US and CT is suggestive of urachal abnormalities. Magnetic resonance imaging offers the advantage of multiplanar imaging and may be useful to clearly determine the involvement of the urinary bladder or of other adjacent structures [9-10].
CT and MRI are useful to differentiate carcinomas located primarily on the roof of the bladder from urachal carcinomas outside the bladder [11].
For patients with surgically resectable tumours, alternative modality include partial or radical cystoprostatectomy, partial cystectomy plus umbilicotomy, and en bloc resection of the urachus [1]. A lymph node dissection also may help in the control of this cancer.
While there is yet no proven role for neoadjuvant or adjuvant chemotherapy, combinations of 5-fluoruracil with cisplatin are active in those with metastases [12].

Differential Diagnosis List

Final Diagnosis

Urachal adenocarcinoma

URL:	https://www.eurorad.org/case/12020
DOI:	10.1594/EURORAD/CASE.12020
ISSN:	1563-4086