Localized cystic renal disease

Localized cystic renal disease (LCRD), also known as localized cystic kidney disease, is an uncommon, non-familial, non-progressive disease characterized by clusters of cysts within the normal renal parenchyma. It can be confused with unilateral autosomal dominant polycystic kidney disease (ADPKD), multilocular cystic nephroma (MLCN), or cystic neoplasm. 

Epidemiology

Variable age of presentation reported from 16 to 83 years. Median age is 50 years old with a proposed male predilection ^1-3.

Clinical presentation

Localized cystic renal disease can present as an incidental finding due to imaging for other reasons. Hematuria, pain and abdominal mass have also been described.

Pathology

Reported cases do not encompass a large number. When pathological samples have been obtained the following characteristics were displayed:

• segmental involvement of the kidney with conglomerate, non-encapsulated cysts of varied sizes, lined with flattened epithelium; cysts appear between regions of normal or atrophic parenchyma
• smooth walled cysts with either thin yellow fluid or hemorrhagic contents
• papillary formation and calcification are not a feature
• same gross histological appearance as autosomal dominant polycystic kidney disease (ADPKD)

Radiographic features

Renal cysts in localized cystic renal disease can involve segments of the kidney or the entire kidney but are always unilateral. The key feature is that the cysts are separated by normal or atrophic renal parenchyma.
Unlike ADPKD, localized cystic renal disease is unilateral, and other organs do not have cystic involvement. In contrast to cystic nephroma, no capsule is seen around the cysts. 

Ultrasound

Ultrasound shows multiple small simple cysts in a segmental or unilateral distribution with normal renal parenchyma in non-affected segments and intervening between cysts. The contralateral kidney is unaffected ². There is no Doppler signal in the cysts ³.

CT

CT findings are characteristic:

• segmental/unilateral renal involvement
• normal or atrophic parenchyma separating the cysts
• normal contralateral kidney
• non-encapsulated mass
• can have scattered calcification in cyst walls
• hemorrhagic high attenuation cysts usually resulting from trauma

MRI

• T2: multiple cysts of high T2W signal intensity, normal intervening parenchyma
• T1 C+ (Gd): no enhancing nodularity
• MRA: increased intensity of the main renal artery and splaying of the intrarenal vessels around cystic structures

Treatment and prognosis

There is a good prognosis and no potential for malignant transformation. Partial and total nephrectomy may be performed when there is a suspicion of malignancy or the localized cystic renal disease is not recognized for its benignancy ¹. 

Differential diagnosis

The main differential is unilateral autosomal dominant polycystic kidney disease (ADPKD). Others include:

• multilocular cystic nephroma (MLCN) 
• renal cystic neoplasm

See also

• adult cystic renal disease