Localized cystic disease of the kidney

Localized cystic disease of the kidney
Diagnosis in short
LM	cysts with cuboidal or flat lining epithelium - contiguous with renal collecting ducts; renal parenchyma (renal tubules or glomeruli) with in septations; +/-foamy histiocytes; +/-refractile material within the cysts
LM DDx	cystic renal tumours (cystic clear cell renal cell carcinoma, cystic nephroma, multilocular cystic renal neoplasm of low malignant potential), hereditary cystic renal disease (autosomal dominant polycystic kidney disease)
Site	kidney
Signs	+/-hematuria (uncommon), often incidentaloma
Symptoms	abdominal pain - due to mass effect
Prevalence	very rare
Radiology	localized cystic disease, Bosniak classification 2 or 3
Prognosis	benign
Clin. DDx	cystic renal cell carcinoma
Treatment	excision for diagnosis

Localized cystic disease of the kidney is a rare benign entity that should be separated from hereditary cystic kidney diseases and cystic renal tumours.

It is also known as segmental cystic disease of the kidney, unilateral cystic disease of the kidney and benign multilocular cyst of the kidney.

General

• Rare and benign.
• No family history of polycystic kidney disease.

Presentation:

• Usually an incidental finding (7 of 9 cases).
• Hematuria - uncommon (2 of 9 cases).

Radiology:

• Bosniak classification 2 or 3.
• No cysts in other organs - liver, pancreas.

Gross

Features:

• Focal cystic lesion(s) without a capsule involving the renal papillae +/-renal cortex.
  • Contain clear or light-yellow serous fluid.

Note:

• Focal - only part of the kidney should be involved.

Microscopic

Features:

• Cysts with cuboidal or flat lining epithelium.
  • Contiguous with renal collecting ducts.
• Renal parenchyma (renal tubules or glomeruli) with in (cyst) septations.
• +/-Foamy histiocytes.
• +/-Refractile material within the cysts.

Notes - negatives:

• No significant inflammation.
• No capsule.
• No papillary hyperplasia.

DDx:

• Cystic renal tumours.
  • Cystic clear cell renal cell carcinoma.
  • Cystic nephroma.
  • Multilocular cystic renal neoplasm of low malignant potential - previously known as multilocular cystic renal cell carcinoma.
• Hereditary cystic renal disease, e.g. autosomal dominant polycystic kidney disease.

Sign out

Left Kidney, Radical Nephrectomy:
     - Localized cystic disease of the kidney, see microscopic description.
     - NEGATIVE for malignancy.

Micro

The sections show multiple large cortical cysts. There is relative sparing of the parenchyma in the lower pole. The cyst walls are fibrotic, contain parenchymal remnants and have foci of calcifications. The cyst lining consists of flatted epithelium without appreciable cytoplasm. No cyst lining cell atypia is present. The cyst lining cells are POSITIVE for AE1/AE3 and NEGATIVE for CD34.

Comment: It is noted that the contralateral kidney is unremarkable on imaging. The findings are in keeping with localized cystic disease of the kidney, a rare benign finding that can mimic a tumour.[1]

1. Am J Surg Pathol 37 (4): 506-13. doi:10.1097/PAS.0b013e318271eff9. PMID: 23211292.

See also

• Cystic kidney diseases.