A renal cyst is a fluid collection in the kidney

Kidney

The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

. There are several types based on the Bosniak classification. The majority are benign, simple cysts that can be monitored and not intervened upon. However, some are cancer

Cancer

Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...

ous or are suspicious for cancer and are commonly removed in a surgical procedure called nephrectomy

Nephrectomy

Nephrectomy is the surgical removal of a kidney.-History:The first successful nephrectomy was performed by the German surgeon Gustav Simon on August 2, 1869 in Heidelberg. Simon practiced the operation beforehand in animal experiments...

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Numerous renal cysts are seen in the cystic kidney disease

Cystic kidney disease

Cystic kidney disease refers to a wide range of hereditary, developmental, and acquired conditions. With the inclusion of neoplasms with cystic changes, over 40 classifications and subtypes have been identified. Depending on the disease classification, the presentation of disease may be from birth,...

s, which include polycystic kidney disease

Polycystic kidney disease

Autosomal dominant polycystic kidney disease is an inherited systemic disorder that predominantly affects the kidneys, but may affect other organs including the liver, pancreas, brain, and arterial blood vessels...

 and medullary sponge kidney

Medullary sponge kidney

Medullary sponge kidney is a congenital disorder of the kidneys characterized by cystic dilatation of the collecting tubules in one or both kidneys. In people with nephrolithiasis, the frequency of medullary sponge kidney has been reported by various authors to be 1221%. The disease is bilateral...

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Epidemiology

Up to 27% of individuals greater than 50 years of age may have simple renal cysts that cause no symptoms.

Bosniak classification

Renal cysts are classified as either malignant or benign using the Bosniak Classification System. The system was created by Dr. Morton Bosniak, a faculty member at the NYU Langone Medical Center in New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

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The Bosniak classification categorizes renal cysts into five groups.

Category I

Benign simple cyst with thin wall without septa, calcifications, or solid components. It does not enhance with contrast, and has a density equal to that of water.

Category II

Benign cyst with a few thin septa, which may contain fine calcifications or a small segment of mildly thickened calcification. This includes homogenous, high-attenuation lesions less than 3 cm with sharp margins(Rich Kosak) but without enhancement.

Category IIF

Well marginated cysts with a number of thin septa, with or without mild enhancement or thickening of septa. Calcifications may be present; these may be thick and nodular. There are no enhancing soft tissue components. This also includes nonenhancing high-attenuation lesions that are completely contained within the kidney and are 3 cm are larger.

Category III

Indeterminate cystic masses with thickened irregular septa with enhancement.

Category IV

Malignant cystic masses with all the characteristics of category III lesions but also with enhancing soft tissue components independent of but adjacent to the septa.

External links

• Bosniak classification, RadsWiki