34 mm Cortical Renal Cyst: Size, Risks, and Treatment Options

What Is a Cortical Renal Cyst?

A fluid-filled sac arising from the renal cortex (outer kidney). Most are simple cysts—benign, asymptomatic, and incidentally discovered on imaging.

Significance of 34 mm Size

A 34 mm cyst is classified as large (≥3 cm). Size alone does not indicate malignancy; Bosniak classification (based on CT/MRI features) determines cancer risk. Simple cysts (Bosniak I) remain benign regardless of size.

Potential Complications

• Pain (capsular stretching)
• Hemorrhage into the cyst
• Infection (rare)
• Obstruction of urinary flow (if hilar)

Management

• Asymptomatic, simple cyst: Surveillance imaging (ultrasound/CT) at intervals.
• Symptomatic or complex cyst: Options include percutaneous aspiration ± sclerotherapy, laparoscopic deroofing, or partial nephrectomy.

Prognosis

Excellent for simple cysts. Malignant transformation is exceedingly rare. Regular follow-up ensures early detection of any change.