Bosniak Cyst

Diagnosis: Bosniak Cyst - Definition, Causes and Treatments

Kidney cysts are usually discovered through computer tomography, and the term ‘bosniak cyst’ refers to a classification system established by Dr. Morton Bosniak, a radiologist whose research has taken medical developments in this field to another level. Urology in particular has benefited from Bosniak’s work, and with the help of radiology and modern technology it is now possible to discover kidney cysts early on and treat them successfully. This article aims to provide an ‘easy-to-understand’ guide for people who are interested in this topic or who may carry a bosniak cyst.

What Is a Cyst?

Speaking in simple terms, a kidney cyst is an individual hollow capsule that is filled with fluid and is usually located in the parenchyma which is a part of the kidney. In most cases, a cyst is developed as a result of a genetic defect or is simply an abnormal growth in the body. Smaller and individually occurring cysts are often not detected and sit inside the body for years. These types are often discovered ‘by accident’ through sonography scans. These types of cysts can occur in any of us, and they are absolutely harmless. The affected person does usually not experience any discomfort or pain, and the cysts (even when discovered) do not have to be removed. However, a larger bosniak cyst is a different story- it can cause pressure inside the kidney and obstruct their function. These types of cysts rarely occur in people under the age of 50, and those who are under 29 years old hardly ever carry any type of kidney cyst. But as the age increases, the chances of developing a cyst also rise.

What Is the Bosniak Classification?

Dr. Bosniak has developed a classification system to determine whether a kidney cyst is dangerous and has to be treated, or whether it is a harmless type that needs no further attention. Here is the list of renal cystic disease according to Bosniak:

Bosniak I: Describes a benign cyst that is filled with water which is no risk to the patient’s health, and does not need any treatment.
Bosniak II: A benign cyst that has very thin septa (‘cross walls’) and has slight traces of chalky substance in the septa (‘calcification’) or outer walls that holds various types of fluids. Due to the fact that both septa and other substances occur in small amounts, this cyst is only malignant in 5% of cases, and frequent check-ups are usually sufficient enough to prevent any complications.
Bosniak IIF: This type of cyst is not usually malignant but the thick septa and relatively high amount of calcification may indicate complications and require ‘follow ups’. The cyst must be observed to rule out problems or negative developments.
Bosniak III: Kidney cysts in this category can require a surgical procedure due to the fact that the calcifications are thick and grainy, and the thickness of the septa may be of alarming nature.
Bosniak IV: A bosniak cyst classified ‘IV’ is undoubtedly of malignant nature and indicates cancerous developments in the kidney in almost 90% of cases.

What Are Therapy Options?

As mentioned earlier on, a bosniak cyst that is benign and does not affect the patient requires no treatment at all. However, if the cyst does cause discomfort, a simple procedure can help the patient to feel better. This procedure is usually done through a puncture that releases the fluids and eases the pressure. If the cyst cannot be classified 100% benign yet, regular check-ups are a must to prevent missing any crucial developments that may be of cancerous nature. The tests usually involve a computer tomography as well as a small test of the fluids. Once any malignant developments are ruled out, the cyst does not have to be removed but should still be followed up regularly – just in case. In very unfortunate cases, the cyst becomes a cancerous tumour that needs to be removed urgently. The patient generally undergoes a surgery where the cyst is taken out in its entirety (as apposed to releasing the fluids only). In extremely severe cases, the entire kidney may have to be removed.

To avoid this, it is very important to ensure regular follow-ups because the sooner cancer is detected, the higher is the success rate.