Genito Urinary Case 1: Renal Cyst

Spine x-ray shows severe osteoarthritic changes of lower lumbar spine. Incidentally there is a soft tissue mass overlying left renal area. Workup of this incidental mass turned out to be Simple Renal cyst.

Renal Masses are often detected as an incidental finding on KUB or IVP.  Ultrasound would be the first test of choice to characterize the mass since no IV contrast or radiation is used. It is ideal for children, pregnant women and patients with renal failure. If the lesion is clearly cystic, no further test is necessary. If solid, contrast CT should be done.

Simple Renal Cyst:

• Commonest form of cysts
• May be single or multiple
• Usually cortical but can also occur in medulla

Ultrasound characteristics:

• Well defined, with sharp margins and thin walls
• Anechoic
• Good sound transmission (posterior enhancements)

Contrast CT characteristics:

• Well defined  thin walled mass
• Low attenuation (lower density compared to renal parenchyma)
• No significant enhancement of walls

MRI: is useful when US is equivocal and contrast CT could not be done because of renal failure.

• Low signal mass on T1 weighted images
• High signal (white) on T2
• No enhancement with contrast

Complicated Cyst should be considered when there are:

• Thick wall
• Internal echoes
• Septa
• Calcifications
• Mural nodules
• Fluid with increased CT attenuation 

A simple cyst can be complicated by either infection, carcinoma, or hemorrhage