Teaching Case

A 25-year-old woman presented with vague left flank discomfort for 2 months. No history of other urinary symptoms. The laboratory results, including complete blood counts, renal function parameters, serum electrolytes, and urinalysis were within the normal range.

Abdominal CT revealed the left kidney was surrounded by a massive multilocular cystic lesion in the perinephric space. The cystic lesion extended from the left diaphragm to the left iliac region and displaced surrounding structures without evidence of invasion. The left kidney had smooth contour and normal contrast enhancement. Excretory phase CT showed no pelvicalyceal dilatation. These findings were in keeping with left renal lymphangiectasia.

Renal lymphangiectasia contributes to approximately 1% of all lymphangiomas [1]. Lymphangiomas are a disease that happens as a result of the obstruction of lymphatics in the developmental period. In renal lymphangiectasia, it is caused by the non-communication of peri-renal and peri-pelvic lymphatic channels with larger retroperitoneal lymphatics [2]. When this drainage is obstructed, the dilatation of renal lymphatics forms unilocular or multilocular collections in perinephric spaces or pelvic sinuses [3].

Most patients are asymptomatic and diagnosed as an incidental finding. They may have nonspecific symptoms like flank pains, haematuria, and altered renal functions [4]. This disease has been reported in adults as well as in children of both sexes [5, 6].

Imaging studies play an important role in establishing the diagnosis. Ultrasound studies show thin-walled multicystic collections in perinephric or peri-pelvic regions [7]. On CT scan, the lesion appears as a well-defined multilocular fluid collection in perinephric or peri-pelvic regions with septations [5].

The main differential diagnoses are polycystic kidney disease and hydronephrosis. In polycystic kidneys, the renal cortex has cysts within, while in renal lymphangiectasia, the renal cortex is normal. In hydronephrosis, delay phase CT would be helpful which depicts dilatation of the pelvicalyceal system, whereas, in renal lymphangiectasia, cystic lesions are not communicated with the renal collecting system. Urinoma can be diagnosed with excretory phase CT, showing contrast leaking from the urinary tract.

No treatment is indicated for asymptomatic patients. However, symptomatic large collections are treated by marsupialisation or nephrostomy [8].