Katsuya Naruse, md, Department of Urology, Aichi Medical University School of Medicine, Nagakute-cho, Aichi 480-1195, Japan. Email: email@example.com
Abstract: This report describes a case of primary leiomyoma of the ureter in which only partial ureterectomy was performed based on the diagnosis of benign tumor by rapid diagnosis using a frozen section during the operation. Surgical treatment was opted for upon diagnosis of a submucosal tumor of the right ureter, with no abnormal findings in the ureteral mucosa by ureteroscopy. To our knowledge, nine cases have been reported worldwide since 1955, suggesting this case to be the 10th.
Leiomyoma rarely develops in the urogenital organs. There have been even fewer reports of leiomyoma with ureteral origin. Ureteral leiomyoma often causes hydronephrosis, making it difficult to diagnose. Therefore, total nephroureterectomy is often performed because of the possible diagnosis of malignant tumor. As the technology of urethroscopy has advanced in recent years, the possibility of malignant tumor can be excluded by preoperative examination, increasing the number of reports of cases in which the kidney was preserved. We experienced a case of primary leiomyoma of the ureter in which partial ureterectomy was performed because a submucosal benign tumor was suspected on ureteroscopic examination. The present report describes this case together with a review of the published work.
The patient was a 38-year-old man, with a history of reflux esophagitis and gastric ulcer. During a regular check-up by a primary care physician, hepatic dysfunction was detected. Abdominal computed tomography (CT) scan revealed hydronephrosis of the right kidney, in addition to fatty liver. CT showed a tumor at the lower end of the ureter, with a density equal to that of the ureteral wall, which appeared to be the cause of hydronephrosis. A well-defined defect of 3 cm in diameter was identified at the lower end of the right ureter by drip infusion pyelography (DIP) (Fig. 1). Because of the possibility of a tumor in the right ureter, the patient was referred to the urology department of our hospital.
There were no specific abnormalities at the initial physical examination. Although mild hepatic dysfunction, possibly resulting from fatty liver, was found on laboratory examinations, the findings of urinary cytology and hematuria were negative.
Ureteroscopic examination showed a mucosal swelling, pressing into the ureteral lumen, though the surface was covered by normal mucosa. Three biopsies were taken from this lesion. Cytological and pathological examination of biopsies of the right ureter showed no evidence of malignancy.
With the diagnosis of submucosal tumor of the right ureter, partial ureterectomy of the right ureter was performed. The tumor did not adhere to the tissue surrounding the ureter and was easily dissected. An approximately 4-cm length of the ureter, together with the tumor, was dissected and subjected to rapid diagnosis using a frozen section. After confirming the absence of malignant features by pathological analyses, end-to-end anastomosis of the ureter was performed by means of sutures with 6-needle knots using 4–0 bicryl thread. The surgery was completed by placing a 6F double J ureteral stent. The dissected tumor was a solid tumor of 35 mm × 13 mm with a white cut-surface. Because immunostaining showed α-smooth muscle actin (+), desmin (+), and muscle-specific actin (+), it was diagnosed as a primary benign leiomyoma from the ureteral muscularis (Fig. 2a,b). The ureteral stent was removed 3 weeks after surgery. DIP performed 6 months after surgery showed no defect or hydronephrosis (Fig. 3).
Non-epithelial benign ureteral tumor of mesodermal origin is a rare disease, and ureteral leiomyoma is even more rare.1 According to our research, only three cases in Japan and six cases in other countries have been reported since the case report by Leighton et al. in 1955,2–10 making the present case the 10th (Table 1). Apart from one case in an infant, most of the cases were in patients aged 30–40, including the present case aged 38. The lesions were located in the right ureter in six cases and in the left in four cases. Six cases were in men and four in women. The sites of the lesion were in the upper, middle and lower parts in four, one and four cases, respectively. There were no significant differences in the location of the lesion, sex and site of development.
The mechanism of development remains unclear, although inflammation, chronic stimulation, occlusion and trauma are suspected. In two cases, the patient had a history of ureterolithiasis, but not in the present case. Ikota et al. reported a diffuse leiomyoma of the ureter as a complication of multiple endocrinoma (MEN) type 1.3 In MEN type 1, the complication of multiple leiomyoma is recognized in a variety of organs including the esophagus, stomach, lungs, uterus and skin, but this case was the only one to develop in the ureter. It has been suggested that the MEN type 1-associated gene may have a causal relationship to multiple leiomyoma.
The diagnosis is made by diagnostic imaging such as excretory urography, retrograde urography or computed tomography (CT) and urinary cytology, as for other ureteral tumors, but there are no characteristic findings.
Surgical treatment was performed in nine out of 10 cases. Partial ureterectomy preserving the kidney was performed in only four cases, including the present one. In the five other cases, nephroureterectomy was performed without differential diagnosis of benign or malignant tumor before surgery.
It has become possible to diagnose benign tumors by preoperative examination as a result of advancements in ureteroscopic technology. It is important to pay careful consideration to the preservation of renal function with the present case in mind, by performing a quick pathological examination during operation when a nonepithelial benign tumor is suspected on ureteroscopy.