Teaching Case

A 15-year-old female patient with history of bilateral flank pain, which was more severe in the right side, was referred to the radiology department for a CT examination.

Ultrasound in the patient record available from a previous clinic reported a large, multiloculated, anechoic collection in the perirenal (subcapsular) region of the right kidney.
128 slice CT showed a large, low attenuation collection with thin internal septa in the right perirenal region (Fig. 1, 4). A small collection of the same characteristics was seen around the left kidney as well. (Fig. 1)
These collections showed thin enhancing walls on post contrast images. (Fig. 1)
There was no hydronephrosis, hydroureter, nephrolithiasis or leakage of contrast media from the urinary tract.
Due to mass effect from the perirenal collection, distortion of the underlying right kidney parenchyma was noted. (Fig 2, 3)

Renal lymphangiectasia is a rare benign condition accounting for about 1% of all lymphangiectasia. [1] Only 22 cases were reported during the past 23 years in the literature. [1] The largest study that was carried out on retroperitoneal lymphangiectasia consisted of 19 patients. [4] It may be unilateral or bilateral and can occur at any age without gender predilection. [3] It can be seen in any location of the body, usually in the neck (75%-80%), maxillary regions (20%) and rarely in the kidneys. [3] Lymphangiectasia is a developmental malformation of lymphatic tissue with the lymphatic system, causing cystic dilatation of lymphatic tracts. [1, 3, 4] Clinically it is asymptomatic and incidentally diagnosed; if it is symptomatic, the most common findings are abdominal pain, abdominal distention, fever, haematuria, fatigue and impaired renal function. [4] On plain film, a soft tissue mass displacing adjacent organs such as bowel loops can be seen. On IVU, displacement and distortion of the urinary structure without invasion may be visualized. [4] Ultrasound usually shows a thin septated, anechoic fluid accumulation in the perirenal region with posterior acoustic enhancement. [2] The collections have well-defined walls. Internal moving echoes may be due to haemorrhage. [1] Ultrasound can also reveal renal enlargement with loss of cortico-medullary differentiation. [4] CT can clearly show low attenuating peripelvic/perirenal septated cystic collections, while higher attenuations are secondary due to intracystic haemorrhage. [1, 2] The collection may have thin and regular septations or thick and irregular in association with free intraperitoneal fluid in severe cases. [1, 2] MR imaging shows low T1WI and high T2WI cystic collections. [2] The cystic lesion usually shows thin septations with enlargement of the kidney on T2WI. [2] The important differential diagnosis is polycystic renal disease, lymphoma, and Nephroblastomatosis. [5] Complications include haematuria, ascites and impaired renal function with renin-dependent hypertension. [2] The associated findings are renal vein thrombosis, hypertension, and pregnancy-related veno-lymphatic obstruction.