More than once I’ve attended patients who came to me (nephrologist), terrified with the cyst in the kidney accidentally found in a image exam, usually abdominal ultrasound.
Renal cysts are commonly observed in normal kidneys, with an increasing incidence as individuals age. They are benign asymptomatic lesions.
The principal clinical concern about renal cysts is the distinction between a malignant lesion that looks like a cyst and the real cysts. That’s why we usually use the terms “simple cyst” and “complex cysts”. The former means a benign cyst without features of malignant disease. The latter refers to cysts that has some characteristics that could indicate a disguised malignant lesion.
One might say that simple renal cyst is the white hair of the kidney. Everyone will get yours as age comes. Simple renal cysts may be solitary or multiple and bilateral. They typically produce no symptoms or signs.
It is so common that, people over 60 may have up to 4 cysts in each kidney and it does not mean any disease. If it is very common in elderly, is not unusual bellow 50 years, and, you don’t expect to find even one renal cyst bellow 30 years.
The finding of a cyst in young adults or multiple cysts in older adults might indicate a disease called polycystic kidney disease.
Rarely, a simple cyst can be associated with rupture (hemorrhage), hematuria, pain, abdominal mass, infection, and/or hypertension.
It’s important to highlight that a simple cyst NEVER becomes a cancer. What sometimes might happens is a misdiagnosed complex cyst. But it’s rare.
The ultrasound, at most of the times, easily distinguishes the simple from the complex cysts. When a doubt arises, the doctor asks for a CT scanning to better understand the image.
To help diagnose and manage these lesions, the Bosniak renal cyst classification system was created. It’s divided in four categories as shown bellow
- Category I � This is a benign simple cyst with a thin wall without septa, calcifications, or solid components.
- Category II � These are benign cystic lesions in which there may be a few thin septa; the wall or septa may contain fine calcification or a short segment of slightly thickened calcification. It is not cancer.
- Category III � These are indeterminate cystic masses that have thickened irregular or smooth walls or septa. Approximately 40 to 60 percent are malignant The remainder, such as hemorrhagic cysts, chronic infected cysts, and multiloculated cystic nephroma, can not be considered simple cysts, but are still benign lesions.
- Category IV � These lesions (85 to 100 percent of which are malignant) have all the characteristics of category III cysts plus they contain enhancing soft-tissue components that are adjacent to and independent of the wall or septum.
If you have a category I ou II kidney cysts, no further evaluation are necessary except a ultrasonography every 12-24 months to assure stability of the image.
If you have a Bosniak category III cyst, you must be undergo more specific evaluation. It can be done with a Magnetic resonance imaging and image-guided biopsy or surgical evaluation.
Category IV lesions require surgery, as approximately 85 to 100 percent are malignant.
So, you went through a ultrasound exam and the report says: simple kidney cyst, you can relax because nothing serious was diagnosed.
Portuguese Version: CISTO RENAL
