Primary renal echinococcosis

Abstract

Hydatid disease is caused by Echinococcus species, which are a flat worm with three evolutionary stages during its life cycle. Renal echinococcal infection is an uncommonly encountered infection in northwest China but is endemic in many parts of the world. Renal echinococcosis accounts for about 2–4% of confirmed cases of cystic echinococcosis. We reported three cases of renal echinococcosis presenting with renal colic, which were confirmed by ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and laboratory examination. The treatment of choice for renal hydatid cyst is surgical removal. In this report, one patient underwent removal of the left renal hydatid inner capsule, while the other two patients underwent complete resection of the right kidney under general anesthesia, with no postoperative complications. These cases emphasized the need for further studies to define a standard treatment modality for renal hydatidosis.

Introduction

Echinococcosis, caused by the infection of Echinococcus granulosus, Echinococcus multilocularis, Echinococcus vogeli, and Echinococcus oligarthruscoccosis, is an endemic, chronic,and sometimes fatal parasitic infectious disease. The disease is distributed worldwide, causing serious economic and public health problems [1]. Echinococcosis usually occurs in the liver and lungs, accounting for about 85%, while kidney echinococcosis only accounts for 2–4% of all cases [2]. Successful treatment of isolated renal hydatid cysts is rare and hereby we report our case as an example of treatment of this condition.

Case presentation

Case 1

A 27-year-old female patient complained of intermittent pain in the left lumbar and back for 2 months. The patient was a herdsman, living in the Tibetan Autonomous Prefecture of Yushu, with a history of living in the endemic area, and contact with cattle, sheep, dogs, wolves and other animals. Physical examination was positive for percussion pain in the left renal area. Intravenous pyelography revealed hydronephrosis and morphological changes of the upper left ureter. Computed tomography of the urinary system revealed a cystic mass in the upper pole of the left kidney with a "ribbon" sign (Fig. 1). The renal pelvis and ureter of the left kidney were fully dilated. The extrarenal pelvis of the right kidney and other organs were normal. Laboratory results indicated an increase in eosinophils. Routine investigations and chest X-ray were normal. After improving the examination, the patient underwent left open lumbotomy and sterilization of the cyst using scolicidal solutions to prevent further spreading or anaphylactic reaction. Patient was discharged in stable condition on the third postoperative day and oral treatment with albendazole for 3 months with no recurrence during follow-up.

Fig. 1.

Hydatid cyst in left kidney (7.9 ×7.3 centimeter size).

Case 2

This case is concerning a 72-year-old man who lived in Qinghai province, in China, near the pasturing area, came to hospital with a 6 years history of recurrent pain in the left loin. The patient was a farmer and denied the history to contact with animals such as dog and fox. Outpatient ultrasonography indicated left kidney occupation (Fig. 2 A, B). Computed tomography revealed an heterogeneous and multivesicular cyst with a maximum cross-section of 82.4 × 79.2 mm and calcified wall; also, daughter cysts were described (Fig. 2 C, D). There was no abnormality in cardiopulmonary diaphragm color ultrasound and laboratory tests. The urine sediment analysis showed no abnormalities. The left kidney was completely resected under general anesthesia, hemostasis and anti-infection treatment were given after surgery, and the patient was discharged 16 days after surgery.

Fig. 2.

(A, B) Ultrasound images of complex left renal cyst. (C, D) Magnetic resonance imaging T1-weighted and T2-weighted images of left renal incidentaloma.

Case 3

A 32-year-old Tibetan man from remote mountainous areas presented with a pain in right lower back and painful urination. At the same time, there is a foreign body excreted from the urine. He denied the history of other chronic disease. He had a habit of raw meats ingestion. Renal function tests indicated mild impairment of left renal function, mainly manifested by slightly reduced GFR. Other laboratory results including blood routine examination, liver functions, and tumor markers were normal. Serological tests of hepatitis B and C were also negative. Urine acidobacteria and tuberculosis related tests were all negative too. After admission. Mild dilation of the upper right renal ureter with abnormal. Further examination of the bladder is abnormal. MRI revealed abnormal signal shadow at the upper level of the right kidney with a size of 36 × 22 × 21 mm. Hydatid rupture possible (Fig. 3 C, D). The surgical treatment was complete resection of the right kidney under general anesthesia, and symptomatic treatment such as indwelling drainage tube, hemostasis and anti-infection was given after surgery.

Fig. 3.

Magnetic resonance imaging T1-weighted and T2-weighted images of right renal incidentaloma.

Discussion

Postoperative pathological examination showed a typical hyalinous degeneration of germinal layer and fibrous tissue, a large number of lymphocytes and plasma cell infiltration (Fig. 4). A polymerase-chain-reaction assay identified Echinococcus granulosus, diagnosis of cystic echinococcosis in three cases. Adult worms of Echinococcus are mainly parasitic in the small intestine of canids, felines, and hyenas, The parasite eggs hatch in the small intestine of the intermediate host after penetrating the organism, pass into portal venous system or lymphatic system and reach the liver and lungs [4]. The renal involvement we reported was unilateral; However, cases of bilateral or grossly widespread disease were reported [5], [6]. All patients in this report came from pastoral or semi-agricultural pastoral areas. Therefore, the patient's living environment, living habits and contact history with intermediate host are very important for the diagnosis of this disease.

Fig. 4.

The post-operative pathological report showed hydatid disease (‘bubbly echinococcus’) with chronic inflammation and a granulomatous reaction:the laminated and germinative layer is shown (red arrows).

Echinococcus granulosus develops slowly in the human body, and patients can survive for 40 years or more. In the early stage of infection, there are no obvious clinical symptoms [7]. As the hydatid cysts gradually enlarge, the most common symptoms of renal hydatid disease include a palpable mass in the waist (41%), low back pain (35%), hematuria (35%), and proteinuria (9%). When hydatid breaks into the collecting system the typical grape skin liked amorphous material will presence in the urine. In this case report, all the 3 patients had different degrees of low back pain and some patients had hydronephrosis, urination discomfort, powdery vesicles and foreign body discharge. Renal echinococcosis is easily confused with other diseases, such as simple renal cysts, hydronephrosis, and renal tumors. Renal hydatids are divided into closed and open types according to the communication between cyst and renal collecting system. Clinically, renal colic and urine abnormalities (cloudy urine with pigmented hydatid cyst walls or echinococcosis excretion) are used to distinguish the types. Open type can make a definite diagnosis based on the expelled hydatid cyst wall. In closed type patients, the thickened cyst wall and internal mixed echo ultrasound are often found in ultrasonography due to lumbar and abdominal pain, which can be distinguished from general renal cysts.

Radiological procedures are the most important tool in the diagnosis of hydatid cyst. The enzyme-linked immunosorbent assay (ELISA) test has an 80% sensitivity at initial diagnosis for hydatid cyst. The ascus and the floating membrane are the characteristic features of echinococcosis. However, compared with USG, high-dose CT can more easily identify spot-like, ribbon-like, eggshell calcification and water density within daughter cysts and calcifications, or multiple circular cystic low-density images of varying sizes. CT can more accurately describe the size, location and the relationship between hydatid and neighboring organs [8], [9]. An MRI is an acceptable alternative to a CT scan. MRI detects multiple or single lesions with high signal intensity, consisting of multiple thin walls and thick surrounding low-signal edges. The diagnosis of renal Echinococcus is based on history,imaging, pathological and serological findings.

Surgery is the most effective treatment for hydatid cysts, complex renal echinococcosis can be treated by nephrectomy to avoid recurrence, especially in cases of complete destruction of the kidney,Kidney saving surgery can be performed in 75% of cases, but the risk of small vesicle spread is higher and there is a risk of recurrence. In this group, two patients with echinococcosis had large cysts, which compressed the renal parenchyma and caused the renal parenchyma to atrophy into a thin layer, so the total nephrectomy were performed, but in the first case, the internal capsule was completely removed, during the operation, the extravasation of the cyst fluid was promptly removed, and the surrounding tissue was tightly protected with gauze to prevent the extensive planting of the original cephalic segment. After the removal of the internal capsule, the outer wall was wiped with a gauze ball dipped in hydrogen peroxide to kill the protoscolex, and washed with the normal saline. All patients were on postoperative oral albendazole with regular follow-up since 3 months which has been uneventful, so there was no recurrence.

Author statement

We declare that we have read the reviewers’ remarks and have taken them into account.

CRediT authorship contribution statement

Haining Fan: Writing – review & editing, Writing – original draft, Conceptualization. Chuanchuan Liu: Writing – review & editing, Writing – original draft, Conceptualization. Haojie Li: Writing – review & editing. Zhuoma Dawa: Writing – review & editing, Writing – original draft, Resources.

Author agreement

We agree to the eventual publication of the article if it is accepted.

Consent

We declare that the consent is not necessary.

Ethics approval

We declare that the approval of the ethics committee is not necessary.

Funding

This research was funded by the Fourth Qinghai Scholars Program (2025-qhxz-fhn).

Declaration of Competing Interest

We declare that we have no conflict of interest.