American Urological Association - Medullary Sponge Kidneys
Medullary Sponge Kidneys
- A.k.a. Cacchi Ricci disease, characterized by multiple cysts in papillary collecting ducts of 1 or more renal pyramids.
- Developmental defect of collecting system.
- RET oncogene implicated, which plays a role in collecting duct development.
- Most cases are sporadic; 5% hereditary autosomal dominance.
- Most encountered in adults, detected incidentally on radiography during work-up for nephrolithiasis.
- Males > females.
- Usually bilateral.
- May also present with hematuria, stone formation in dilated duct, obstruction, and UTI.
- Up to 1/5 of nephrolithiasis patients reported to have MSK.
- Radiologically, collecting ducts ectasia results to "bouquet of flower" or "bunch of grapes".
- Most cysts are <1 cm located in renal pyramids (image A) & (image B).
- Kidneys are usually not enlarged.
- Papillary collecting ducts are dilated and lined with cuboidal or flattened epithelium.
- Focal cellular stratification may be seen.
- Cyst lumen may contain calculi or inflammatory cells.
- Calculi may cause inflammation.
- Benign course if calculi and infection are controlled.