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# Other renal cysts: medullary, dysplastic, acquired

- Lesion

Not every cystic kidney is polycystic: some cysts sit in the medulla, some reflect faulty development and some come with age or dialysis.

Updated Nov 12, 2026

## Key points

- Medullary sponge kidney: dilated papillary ducts, calcium stones, hematuria, infection; good prognosis.
- Nephronophthisis: autosomal recessive, polyuria and salt wasting, anemia, growth failure; may come with retinal dystrophy or liver fibrosis.
- ADTKD: autosomal dominant, bland urine, slowly progressive fibrosis; UMOD variants cause early gout.
- Multicystic dysplasia: immature ducts surrounded by mesenchyme, cartilage; often with ureteral atresia.
- Acquired cystic disease: many cortical and medullary cysts in dialysis kidneys, with oxalate crystals and a higher risk of renal cell carcinoma.
- Simple cysts: single or multiple, thin-walled, clear fluid, cortical; very common with age.

## What it is

Several smaller disorders complete the list of renal cysts. Medullary sponge kidney has dilated medullary collecting ducts and causes stones in adults. Nephronophthisis, a recessive ciliopathy, gives small kidneys with corticomedullary cysts and kidney failure in children and teenagers. Autosomal dominant tubulointerstitial kidney disease (ADTKD; once called medullary cystic kidney disease) causes slow interstitial fibrosis in adults, from variants such as UMOD (uromodulin, with gout) and MUC1. Multicystic dysplasia is a developmental error with immature tissue. Acquired cysts follow long dialysis; simple cysts come with age.

## Structure

- Medullary sponge: small cysts in the papillae, often with stones, kidneys of normal size.
- Nephronophthisis: small kidneys, cysts at the corticomedullary junction, tubular atrophy with thickened, laminated tubular basement membranes.
- Dysplasia: cysts of varied size among undifferentiated mesenchyme, smooth muscle and islands of cartilage.
- Acquired cysts: lined by hyperplastic or atypical epithelium; some contain papillary tumours.

## Clinical notes

- In a teenager with polyuria, anemia and small kidneys but bland urine, think of nephronophthisis.
- Dialysis patients are screened for tumours in acquired cysts.

## Memory aid

Sponge for stones, nephronophthisis for children, ADTKD for families with gout, dysplasia for the newborn, cysts for the dialysed and the old.

## Test yourself

Think of the answer, then tap the question to see it.

## What complication is typical of medullary sponge kidney?

Calcium stones in the dilated medullary collecting ducts, with hematuria and infection.

## What distinguishes nephronophthisis from polycystic kidney disease?

Kidneys are small, cysts sit at the corticomedullary junction, and kidney failure occurs in childhood or adolescence.

## Which gene of ADTKD is associated with early gout?

UMOD, which encodes uromodulin.

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## Elsewhere in DurgiPedia

- [Multicystic dysplastic kidney and polycystic kidney disease](https://durgical.com/en/embryology/multicystic-dysplastic-kidney-and-polycystic-kidney-disease/)

## Connections

## Related 4

- [Cystic kidney diseases: comparison table](https://durgical.com/en/general-pathology/cystic-kidney-diseases-comparison-table/)
- [Chronic kidney disease and uremia](https://durgical.com/en/general-pathology/chronic-kidney-disease-and-uremia/)
- [Clear cell renal cell carcinoma](https://durgical.com/en/general-pathology/clear-cell-renal-cell-carcinoma/)
- [Kidney stones](https://durgical.com/en/general-pathology/kidney-stones/)

## Related conditions 5

- [Medullary sponge kidney and medullary cystic disease](https://durgical.com/en/conditions/medullary-sponge-kidney-and-medullary-cystic-disease/)
- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)
- [Renal cell carcinoma](https://durgical.com/en/conditions/renal-cell-carcinoma/)
- [Kidney stones (urolithiasis)](https://durgical.com/en/conditions/kidney-stones/)
- [Congenital kidney anomalies (horseshoe kidney, renal agenesis)](https://durgical.com/en/conditions/congenital-kidney-anomalies/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Polycystic kidney disease: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/polycystic-kidney-disease/) (MedlinePlus, US National Library of Medicine, 2025).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/general-pathology/other-renal-cysts-medullary-dysplastic-acquired/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/other-renal-cysts-medullary-dysplastic-acquired/