A case of an isolated hydatid cyst in the right kidney.

Isolated renal hydatid cyst is rare. Preoperative diagnosis may be difficult because clinical, biochemical and radiologic findings can not eliminate the diagnosis of renal cancer in its cystic form. Open surgery is traditionally the gold standard.

Introduction

Hydatid cyst disease is a parasitosis caused by a tapeworm: Echinococcus granulosus. The kidney is the most commonly affected organ of the urinary tract. However, isolated renal involvement is rare (2–4% of all cases). The causative tapeworm lives in the small intestine of definitive hosts, such as dogs and other canids. Its diagnosis is easy and mainly based on ultrasound and CT-scan. The treatment is mainly surgical.

Case report

A 40-year-old woman, without any noticeable medical history, was admitted into our hospital. She was complaining of the presence of chronic right flank pain and mild fever. The clinical examination was normal. The laboratory findings, including liver, renal function tests and hydatid serology were normal. The CT-scan of the abdomen confirmed a 9 cm renal mass with a 3 cm cyst inside (Fig. 1). Renal hydatid cyst (RHC) was suspected. No other localizations were found. The patient was managed by open surgery: lombotomy. We were obliged to make a tumorectomy because the investigations couldn't eliminate the diagnosis of renal cancer in its cystic form (Fig. 2). The postoperative period was uneventful. The patient was discharged on day 5 after an uneventful postoperative course. He took Oral albendazole for 4 weeks on discharge. Anatomopathology confirmed the diagnosis of hydatid cyst of the kidney (Fig. 3). The patient is on regular follow-up in outpatient department in health and normal renal function.

Fig. 1

CT scan showing a 9 cm cyst on the right kidney.

Fig. 2

Hydatid cyst removed by open surgery.

Fig. 3

Pericystium with lyphocystic infiltrated renal parenchyma and atrophic and dilated renal tubules.

Discussion

The RHC represents about 2.5% of the whole localizations and most often unilateral and unique, however cases of multiple and even bilateral were reported. The RHC might remain asymptomatic for years in case of slow evolvement. The patients with RHC usually present with vague pain in the lumbar or flank region. The patient might present hematuriae, which is a pathognnomonic sign of cyst rupture, a finding that is present in only 10–20% of the cases. The CT-scan remains the most suitable examination. It could be ordered promptly, and mostly for differential diagnosis once the ultrasonographic IV and V types are declared. Differential diagnosis of hydatid cysts of the kidney from other space-occupying renal masses can be challenging. However, the combination of factors such as the slow increase of growth, the characteristic imaging findings, and serological test results can be revealing. Considering the insufficiencies of medical treatment (with bi-imidazoles like albendazole 10–15 mg/kg/day in two divided doses), used especially in cases of small cysts (lower than 30 mm), and the potential risk of interventional radiology, the treatment of RHC remains surgical. The choice of the treatment approach depends on three basic elements: the volume of the mass, the relation of this mass with neighboring tissues and the extra-renal and abdominal localization of another hydatid cyst. Therefore, the lombotomy is the most used approach. Also to avoid the spread of the disease, the cyst should be removed without rupture especially in this case where the diagnosis of kidney cancer is possible. Laparoscopic nephrectomy entails risk of cyst rupture, intra-peritoneal dissemination, and incomplete removal of the hydatid cyst. Retroperitoneoscopic approach is favored and is increasingly used as it provides the same outcome, less morbidity and a better esthetic result but only some studies were published. In our case, we considered feasible a retroperitoneal approach through lombotomy incision. The kidney was reserved, because the hydatid cyst did not invade a major renal part and renal function tests were normal. The cyst was not opened intra operatively. However, partial or total nephrectomy is required in the cases found with almost completely destroyed kidney. Nevertheless, the prognosis remains still very good whenever other localizations are not associated.

Conclusion

A limited number of isolated renal hydatid cysts are reported in the literature. The RHC has to be evoked in all renal cystic lesions, especially in endemic regions of the. Careful diagnosis and complete pathophysiology of urinary tract hydatidosis are needed to be clarified. The surgical approche remains the treatment of choice.