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Tumors of the ureter are rare. We present a case of primary mucinous adenocarcinoma of the ureter diagnosed as chronic pyelonephritis preoperatively. This tumor is postulated to arise from metaplastic glandular mucosa in response to chronic irritation of the urothelium.
Primary adenocarcinoma of the renal pelvis and ureter is an extremely rare tumor, representing less than one per cent of all renal tumors. A preoperative diagnosis is rarely made because the tumor is uncommon. We report a case of primary mucinous adenocarcinoma of the ureter.
A 40-year-old female presented to our hospital with a history of abdominal discomfort and right flank pain for one month. Physical examination was unremarkable. Results of routine hematological investigations were within normal limits. Urine examination showed presence of RBCs and pus cells. Ultrasonography revealed a contracted kidney and no mass was identified. Renal scan showed the kidney as non-functioning; a right nephrectomy was performed with a preoperative diagnosis of chronic pyelonephritis.
On gross examination the kidney weighed 195 g and measured 11.5 × 6.8 × 6.5 cm. The capsule was intact and there was increase in perinephric fat. On cut section the pelvicalyceal system was dilated and renal parenchyma thinned out. No calculus was identified. The ureter measured 2.6 cm long with maximum diameter two cm. On cut section the lumen of the ureter was obliterated [Figure 1].
Microscopic examination showed a tumor arising from the ureter and extending into the renal pelvis [Figure 2]. The tumor was composed of mucin secreting tumor cells. Pools of mucin with floating tumor cells were noted [Figure 3]. Invasion was identified consisting of dissecting mucin containing malignant glandular epithelium. Mucin was highlighted by mucicarmine. The kidney showed changes of chronic pyelonephritis and a focal area showed presence of acute inflammatory exudate and yeast forms of candida.
Malignancies originating within the renal pelvis and ureter are uncommon. Most of them are transitional cell carcinomas accounting for approximately 90% cases. Less common are squamous cell carcinomas accounting for less than 10% and rarest are primary adenocarcinomas comprising only one percent.
The postulated pathogenesis of adenocarcinoma is related to its frequent association with chronic irritation, inflammation, infection, hydronephrosis and urinary calculi. Glandular metaplasia of the urothelium that develops as a response to injury may progress to dysplasia and adenocarcinoma. These tumors are subdivided into tubulovillous, mucinous, and papillary non-intestinal categories. The first two groups representing intestinal adenocarcinoma constitute 93% of cases. Mucinous adenocarcinoma has a better prognosis and occurs in elder patients, but the papillary non-intestinal variety occurs in younger individuals and is not necessarily associated with infection.
Primary mucinous adenocarcinoma of the renal pelvis and ureter occurs in patients who are beyond middle age. Patients are often asymptomatic. Hematuria is the most common presenting sign while loin pain and palpable abdominal mass signifies a late stage. Radiological studies may not be able to identify a malignant tumor. Literature review reveals a high frequency of reporting this otherwise rare tumor in India and Japan and suggests an inflammatory, environmental or dietary etiology.[5,6] A case of primary mucinous adenocarcinoma of the renal pelvis has been reported in our institution. The tumor had masqueraded as pyonephrosis clinically and was diagnosed on histopathologic examination.
A preoperative diagnosis of ureteric adenocarcinoma is difficult to achieve. Most cases are diagnosed from the resected specimen postoperatively. The treatment is nephrectomy with ureterectomy. Although it is uncommon, the possibility of this tumor should be kept in mind, especially in patients with a renal stone accompanied by hydronephrosis and chronic inflammation. Japan (12) and India (10) have reported the highest number of cases of primary adenocarcinoma of ureter and pelvis while other parts of the world have reported occasional cases. There is need for further research to understand why this carcinoma is more common in these countries than other parts of the world.
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