Bilateral adult renal lymphangioma: A case report

A 59-year-old male patient presented with bilateral flank heaviness more on the left side of 2 months duration. His medical history was significant for CAD and BPH. The laboratory results, including CBC, serum electrolytes, kidney function, and urinalysis/culture, were unremarkable. His physical exam was also unremarkable.

To evaluate his flank heaviness, a renal ultrasound was performed, said ultrasound showcased perirenal fluid collections surrounding both kidneys. These fluid collections showed septations and internal echoes measuring 1.3 cm in maximum thickness on the right side, and 2.2 cm in maximum thickness on the left side.

Therefore, the patient underwent a renal computed tomography scan, thus, showing large bilateral retroperitoneal multilocular perinephric fluid attenuation collections surrounding both kidneys larger on the left side. Said collections measured about 6 cm in maximum thickness on the left side, pushing the left kidney anteriorly, and 3 cm on the right side. There was no visible connection between the collection and the renal pelvicalyceal system, ureters, or contrast leakage into the collection in delayed images.

Lymphangiomas are rare benign neoplasms of mesenchymal tissue attributed to maldevelopment of lymphatic vessels. They can occur in any site, causing failure of the lymphatic tissue to establish a normal connection with the remainder of the lymphatic system. A subtype known as Renal Lymphangiomatosis (RLM) where these growths occur in the retroperitoneum specifically surrounding the kidneys, has been described [1]. It accounts for approximately 1% of all lymphangiomas, can be unilateral or bilateral, and usually presents in early childhood, however, less commonly presents as an incidental finding in adults [2,3].

Less than 50 cases of Renal Lymphangioma have been documented in the literature, of those only 7 were bilateral. What marks this specific case as unconventional and worthy of publication is the age of the patient, presentation with nonspecific symptoms, and the fact that the patient has bilateral RLM. The specific origin of this disorder has not been completely pinpointed to the roots nor completely understood. There may be a familial association in some documented cases which hypothesizes a hereditary origin [4]. On the other hand, others hypothesize an acquired cause, owing to blockage of lymphatic vessels due to obstruction and inflammation, leading to lymphatic ectasia [5]. Although it is mainly a benign condition, cytogenic studies theorised malignant transformation potential due to cytogenic abnormalities in chromosomes 7 and X, which also explains a female predominance [6]. The majority of cases are asymptomatic and are found incidentally during routine investigations. Patients may also present with non-specific (vague) symptoms such as flank heaviness, abdominal pain, renin-dependent hypertension and rarely haematuria [7].

The initial workup is renal ultrasound, which usually reveals a perirenal anechoic fluid collection encasing the entire kidney with internal septations. Adding onto that, it also shows normal renal size, an increase in parenchymal echo pattern, and decreased corticomedullary differentiation. For further evaluation, Computed Tomography usually reveals a well-defined perinephric collection showing fluid attenuation with internal septations and normal renal parenchymal enhancement. In contrasted images, there is no extravasation of contrast into the collection and no communication with the pelvicalyceal system [8,9].

The definitive diagnosis is made via aspiration that reveals sterile, chylous fluid with lymphocyte predominance (approximately 80-90%) and minimal amount of fatty content [10]. Unfortunately, in our case, the patient refused aspiration and therefore, diagnosis was made solely by imaging findings.

After the diagnosis of RLM is made, management options are determined based on the patient’s presenting symptoms. If the patient is asymptomatic, a conservative course is usually preferred. On the other hand, if the collection is large and is causing significant symptoms, the treatment options range from percutaneous drainage to marsupialization and deroofing whether it be using an open or a laparoscopic technique. Furthermore, in some complicated cases such as renal vein thrombosis, a nephrectomy might be warranted [11].