Unusual presentation of urachal adenocarcinoma with genitourinary cutaneous metastasis.

Dear Editor,

The urachus, which is a vestigial structure between the dome of the bladder and umbilicus, usually, retracts from the bladder before birth. However, the urachal remnant was continuous with the bladder cavity even in adults in 32% of bladder in one autopsy study.1 For this reason, tumors may develop from the remnants, most of which are well-differentiated mucinous adenocarcinomas, which is a rare form of vesical malignancy, accounting for <1% of all bladder cancers. Although local spread to the peritoneum is common at presentation, distant metastases without local recurrence are rarely detected following surgical excision of clinically localized disease. To the best of our knowledge, distant metastases have been reported in a number of organs, including the lung, omentum, liver, bone, brain, ovarian, and maxilla.1234 Now we report the first case of genitourinary cutaneous metastasis resulting from urachal adenocarcinoma.

We report a urachal adenocarcinoma metastatic to genitourinary skin in a 53-year-old Chinese man. In May 2008, after admission to Changhai Hospital in Shanghai, imageological examination reveared 2.0 by 1.5 cm mass extending from the vertex of the urinary bladder to the median umbilical ligament, and there was no evidence of metastasis on B-ultrasonic wave and computed tomography. Then a partial cystectomy with urachal remnant resection was performed. Surgical findings indicated no invasion of surrounding bladder tissues and no local extension into the abdominal wall, peritoneum or any viscera other than the bladder. Pathologic examination identified urachal adenocarcinoma that limited to the shallow muscle layer and showed morphologically enteric type differentiation (), mucinous adenocarcinoma () and ring cell carcinoma ().

Histopathology showed the original and metastatic urachal tumor. (a) The overlying urothelium was involved by enteric adenocarcinama. (b) Well-differentiated mucinous adenocarcinoma was seen. (c) There were signet ring cells floating within the mucinous material. (d) Metastatic urachal denocarcinoma destroied the skin of scrotum (H and E) (scale bars = 200 μm).

Two months after surgery, for this complaint a 2 cm diameter mass originated from penile and scrotum was made nothing of. And 5 years later, he was diagnosed with a 10 cm as the longest meridian erysipeloid-like mass on physical examination (). The total resection of penis, scrotum and groin skin, was performed to confirm the origin of the tumor, besides radical total cystectomy and urinary diversion. And postoperative incision was shown as . Histopathological diagnosis of all resected tumors showed mucinous adenocarcinoma that was morphologically similar to the patient's original tumor (). Immunohistochemical studies using the following antibodies (monoclonal; DAKO, Glostrup, Denmark) demonstrated that the neoplastic epithelial cells to be positive for CAM5.2, CDX2, CA199 (Figure ) and negative for p63 (), p53, p16 (data not shown). Currently, the patient (because of poor physical condition) without chemotherapy or radiotherapy remains disease free after 7 months of follow-up.

Traces of the patient for pre- and post-surgery (a) ulcerative lesions located on the prepuce and scrotum; (b) postoperative changes of perineum.

Immunohistochemical staining patterns in urachal carcinoma: (a) Strong, diffuse cytoplasmic staining for CAM5.2. (b) Strong, diffuse nuclear staining for CDX2. (c) Diffuse membranous staining for CA199. (d) The neoplastic epithelial cells stain negative for p63, whereas urothelium stain positive (scale bars = 100 μm).

Primary urachal adenocarcinoma is extremely rare, accounting for <1% of all malignant bladder cancers. Approximately, 20%–30% of these are urachal in origin.5 They may show a variety of histopathological glandular patterns but are most commonly the mucinous type. Age at diagnosis is in the late fifties with a little over 1:1 male: female ratio.4 It may be asymptomatic leading to the diagnosis, but can present with hematuria, pelvic pain, pelvic neoplasm, and urinary infection.6 Unfortunately, no absolute consensus exists regarding diagnostic criteria now. Local recurrence is frequent after surgery. Distant metastases usually occur late in the natural history of the disease. And so it carries a dismal prognosis especially for carcinoma cell metastasis to the skin.7 Cutaneous involvement due to urological malignancy is uncommon, the incidence of cutaneous metastasis from bladder malignancies ranges from 0.84% to 3.60%.8 And this patient is the first to present with genitourinary cutaneous metastasis from urachal adenocarcinoma. They represent a significant challenge because of no consensus on how to manage those cases.

Unlike other cancers, there is currently no standard adjuvant or metastatic chemotherapy or radiotherapy regimen for the treatment of urachal carcinoma.9 Undoubtedly, surgical approach represents the mainstay of treatment for urachal carcinoma, especially for recurrent or metastatic urachal cancer.10 And recently, complete laparoscopic removal of complicated urachal adenocarcinoma seems to be a safe, effective approach. However, the question as to whether partial or radical cystectomy is suitable for localised disease is difficult to answer since urachal tumors are rare.

In general, cutaneous metastases tend to most frequently occur in the vicinity of the primary cancer. Whereas for genitourinary cutaneous metastasis resulting from urachal adenocarcinoma, direct invasion by hematogenous metastasis may be thought to be one of the most important pathways. Currently, because of the limitation of the number of total patients with skin metastasis, there were lots of questions to answer, such as the approach and timing of surgery, the choice of radiotherapy or chemotherapy regiments and the underlying mechanism of cutaneous metastasis.

In summary, our case experience and literature review suggest that the early finding of the urachal mass and complete resection, besides, combined modalities treatment are required for patients with genitourinary cutaneous metastasis resulting from urachal adenocarcinoma.

AUTHOR CONTRIBUTIONS

YHY was responsible for the acquisition of data, drafting and editing the manuscript; XWZ, JGH, HJT were involved in clinical management of the patient and interpretation of data; YZ was responsible for the interpretation of pathology; WHX was the supervisor of clinical management of the patient and interpretation of data.

COMPETING INTERESTS

The authors declare that they have no competing interests.