Rare presentation of urachal adenocarcinoma with skip metastasis to colon.

Urachal carcinoma is a rare malignancy constituting <1% of bladder malignancies. The disease arises from a malignant transformation of rests of enteric epithelium in the urachus. Most common sites of metastasis are lung, liver, and bone. We report a postoperative case of urachal carcinoma presenting with distant metastasis to lung and skip lesions in colon. As both urachal and colon carcinoma share common histopathological features, most of the literature suggested using chemotherapy regimens similar to those recommended for colon malignancies. There are no randomized trials till date regarding the management of urachal adenocarcinomas except for the primary treatment being surgery.

INTRODUCTION

Urachal carcinomas are rare and account for approximately 0.35–0.7% of all bladder cancers.[1] Primary treatment includes surgical excision with partial or total cystectomy along with removal of umbilicus, urachus tract with or without pelvic lymphnode dissection. Common metastatic sites include lung, liver, and bone. Here, we report a case of urachal carcinoma treated with surgical excision, which presented after 2 years of primary surgery, with skip metastasis to colon and lung, and was managed by palliative chemotherapy.

CASE REPORT

A 62-year-old male presented to the radiotherapy department of our institute with complaints of pain abdomen and loss of appetite for past 1 month. His past treatment details revealed that he had similar complaints 2 years back for which he underwent contrast enhanced computed tomography (CECT) scan of chest abdomen and pelvis which showed mass in the upper outer surface of urinary bladder extending anteriorly to the abdominal muscles. There was no abnormal or irregular thickening of the bowel wall. The chest was also clear [Figure 1a]. He underwent laparoscopic partial cystectomy along with excision of urachus, umbilicus, and bilateral pelvic node dissection. Postoperative histopathology [Figure 1b] was suggestive of urachal adenocarcinoma of size 5 cm × 4 cm × 2.5 cm, with tumor cells infiltrating the deep muscle, serosal aspect being free of tumor; and all 10 lymph nodes dissected were also free of tumor. Diagnosed as a case of urachal adenocarcinoma stage-I according to Mayo staging system, he was kept on regular follow-up and presented 2 years later with above-mentioned complaints.

Figure 1

(a) Contrast enhanced computed tomography scan showing mass in the upper outer surface of urinary bladder extending anteriorly to the abdominal muscles. (b) Postoperative histopathology report showing tumor arising from the urachus epithelium and are arranged in form of glands and are infiltrating into the submucosa (right: Low power view H and E, ×100 and left: High power view H and E, ×400)

Repeat CECT scan of abdomen and pelvis showed a large mass involving sigmoid colon extending for a length of approximately 10 cm with maximum thickness of 4.6 cm. Surrounding fat stranding was seen with extension up to anterior abdominal wall. The thickened loop showed loss of fat planes with left psoas posteriorly, and was abutting the distal external iliac artery; however, no definite infiltration was seen.

Lower gastrointestinal endoscopy was suggestive of a large polypoidal growth at 23 cm from the anal verge with ulcerated mucosa; scope was negotiable beyond the growth. Positron emission tomography (PET)-CT scan suggested intensely fludeoxyglucose (FDG) avid well-defined large heterogeneous enhancing soft tissue mass (maximum thickness ~4.9 cm) in the proximal sigmoid colon, with pericolic fat stranding-likely primary [Figure 2a]. The lesion was infiltrating the left psoas muscle. There were ill-defined fat planes with left external iliac blood vessels and adjacent bowel loops. A few intensely avid bilateral external iliac lymph nodes were noted. Intensely FDG avid asymmetrical mural thickening with skip lesions were noted in the descending colon [Figure 2a].

Figure 2

(a) Axial positron emission tomography-computed tomography image showing Intensely fludeoxyglucose avid well-defined large heterogeneous enhancing soft tissue mass in the proximal sigmoid colon, with pericolic fat stranding with infiltration in the left psoas muscle. (b) Axial positron emission tomography-computed tomography image showing increased fludeoxyglucose uptake in the hypodense soft tissue mass in the apical anterior segment of left upper lobe with thin contrast enhancing periphery

Increased FDG uptake was noted in the thin contrast enhancing periphery of large hypodense soft tissue mass noted in apical anterior segment of the left upper lobe [Figure 2b]. Faintly FDG avid mediastinal lymph nodes were noted, probably metastasis.

Biopsy from the colonic growth was suggestive of adenocarcinoma, metastatic. Fine needle aspiration cytology from the left upper lobe lung mass was suggestive of mucinous adenocarcinoma. Thyroid transcription factor-1 immunohistochemistry performed on lung tissue was negative. His carcinoembryonic antigen (CEA) level was normal (9.39 ng/ml).

After multidisciplinary discussion, he was diagnosed as urachal adenocarcinoma with metastasis to colon and lung. The patient was started on chemotherapy with irinotecan, 5-fluorouracil (FU) and leucovorin. After first cycle, patient developed sub-acute intestinal obstruction, for which he underwent diversion loop colostomy; and later chemotherapy was continued.

DISCUSSION

Urachal adenocarcinomas are typically located in the midline, either anteriorly or in the dome and, although often discrete, can form a large mass on the anterior abdominal wall.[1] Urachal carcinomas have higher incidence in men and typically present in the fifth or sixth decade of life. Although the pathogenesis is not well understood, exposure of remnant urachal epithelium to intravesical carcinogens is an unlikely etiology. Common presenting symptoms are hematuria, pain abdomen, irritative symptoms; mucinous or serous discharge from the tract in the umbilicus.

The final diagnosis is made only after exclusion of adenocarcinoma in any other site. Kapoor et al. analyzed six cases of urachal carcinoma diagnosed over a period of 7 years treated with partial cystectomy with bilateral pelvic lymph node dissection and adjuvant radiotherapy.[2] The study illustrated the need for adjuvant therapy to decrease the chances of recurrence but demonstrates the limited availability of prospective trials.

The significance of the present case lies in its unusual way of recurrence after 2 years of primary surgery, at a site (colon), which can easily be misinterpreted as the second primary. Though PET scan clearly demonstrated the extent of disease, but histopathology and immunohistochemistry correlation greatly impacted the true diagnosis of the case, confirming it to be a recurrence, rather than second primary. This is all the more important while choosing chemotherapy drugs in this case.

To date, there are no randomized trials on the management of urachal carcinomas and <300 cases have been reported in the literature. As both urachal and colon carcinoma share a common histopathological features, most of the literature suggested using chemotherapy regimens similar to those recommended for colon malignancies.[3]

The first case report from Japan which showed the effectiveness of Irinotecan in urachal adenocarcinoma was published by Kume et al.[4] in 2006. They confirmed the resemblance of mucin producing urachal carcinomas with colorectal carcinomas pathologically and in rise of CEA levels in both adenocarcinomas. They found that with effective administration of Irinotecan CEA levels decreased from 98.3 to 38.7 ng/ml and pulmonary metastatic lesions were reduced by 60%. The 5 years survival rate reported by many authors is 16–45%.[5]

Mohile et al. in the literature review suggested the effectiveness of IFL (irinotecan, 5-FU, leucovorin) and suggested that this regimen was clinically effective for 5 months following the initiation of treatment for recurrence but the long-term efficacy of chemotherapy for systemic urachal carcinoma is still unknown.[3]

Griffin et al. recently treated a case of metastatic urachal adenocarcinoma with a novel regimen (Gem-FLP: 5-FU, leucovorin, gemcitabine, and cisplatin) and showed regression in the size of liver lesions in the interval imaging post 4 cycles of chemotherapy.[6] However, the patient progressed within 2 months posttreatment completion.

CONCLUSION

We present a rare case of urachal carcinoma with skip metastasis to the lung and colon. Chemotherapy regimen with irinotecan, 5-flurouracil, and leucovorin is found to be effective in the metastatic setting, but the long-term efficacy of this regimen is still unknown.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.