Differentials

CONDITIONS
SIGNS / SYMPTOMS
INVESTIGATIONS

Acquired cystic kidney disease

SIGNS / SYMPTOMS

Clinical history is the most helpful discriminator.

Occurs in the setting of pre-existing renal disease.

INVESTIGATIONS

Kidney size and cysts are usually small as opposed to enlarged kidneys usually seen in autosomal-dominant PKD (ADPKD); however, kidneys may increase in size and resemble those of ADPKD.

Hemorrhage often seen on imaging.

Simple cyst

SIGNS / SYMPTOMS

Common in adults. Incidence increases with age; tend to be uncommon in people <40 years of age.

Absence of family history and not meeting the Ravine criteria is helpful. [40]

Rarely leads to significant pain, rupture, or infection.

INVESTIGATIONS

Diagnosis made on ultrasound. Criteria include absence of internal echoes; strong, sharply-defined distant wall with smooth distinct margins; acoustic enhancement; and a spherical, or slightly ovoid, shape.

Bosniak classification is used to classify renal cysts and defines appropriate management. [64] [65]

SIGNS / SYMPTOMS

Facial angiofibromas, forehead patches, shagreen patches, subungual fibromas, hypomelanotic macules, cortical tubers, subependymal nodules, giant cell astrocytomas, cardiac rhabdomyomas, and pulmonary lymphangioleiomyomatosis.

INVESTIGATIONS

TSC1 and TSC2 gene mutation analysis.

Commercial testing is available.

Most frequent renal findings are angiomyolipomas, renal cysts, and renal cell carcinomas.

von Hippel-Lindau syndrome

SIGNS / SYMPTOMS

Renal cell carcinoma, retinal and/or central nervous system hemangioblastomas, pheochromocytomas, pancreatic cysts, and epididymal cystadenoma.

INVESTIGATIONS

VHL gene mutation analysis.

Commercial testing is available.

Maturity-onset diabetes of the young type 5

SIGNS / SYMPTOMS

Type 2 diabetes mellitus, renal cysts, and genital tract abnormalities. [66]

INVESTIGATIONS

HNF1-beta gene mutation analysis.

Commercial testing is available.

SIGNS / SYMPTOMS

Chronic tubulointerstitial disease and frequent gout, with renal cysts at the corticomedullary junction.

FHx of chronic kidney disease of unknown cause.

INVESTIGATIONS

MRI of kidneys reveals renal cysts typically at the corticomedullary junction.

Magnetic resonance urography shows a medullary nephrogram or a ring-shaped contrast enhancement along the base of the papillae. Thin-cut CT may also be helpful.

UMOD gene mutation analysis (MCKD2), if positive, confirms diagnosis. However, there is a second disease locus for the MCKD1 (MUC1) locus; therefore, mutation analysis will not completely exclude medullary cystic kidney disease if negative.

Commercial testing is available.

Orofacial digital syndrome type 1

SIGNS / SYMPTOMS

PKD occurs in <50% of patients with orofacial digital syndrome type 1 (OFD1), which is a sex-linked disorder.

Renal cysts can develop from tubules and glomeruli.

Age of onset is most often in adulthood, but renal cysts in children have been described.

INVESTIGATIONS

OFD1 gene mutation analysis.

SIGNS / SYMPTOMS

Characterized by tubular dilation of the collecting ducts confined to the medullary pyramids.

Absence of a family history of the disease.

INVESTIGATIONS

Sparing of the cortex on CT or MRI.

Localized cystic disease

SIGNS / SYMPTOMS

Small cysts localized to one portion of the kidney.

Not a genetic disease. Family history is always absent.

Not associated with renal failure.

INVESTIGATIONS

Cystic disease is always unilateral.

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