Horseshoe kidney (also known as renal fusion) is a congenital disorder, affecting about 1 in 400 people, in which a person's two kidneys fuse together to form a horseshoe-shape during development in the womb [7]. This is one of the most frequent malformations of the urogenital tract, affecting approximately 1 in 400 people. During normal development,
the kidneys rotate in such a way that the ureters leave the kidney from its medial aspect and the axes of the kidneys diverge. Renal parenchyma or fibrous tissue make up the bridge connecting the lower poles of the kidneys. The pelvicalyceal system is often minimally dilated and there are often accesory renal arteries or abnormal blood supply [8].Most people affected by this disease are often asymptomatic, with normal kidney function, thus it is often discovered upon autopsy. Nausea, abdominal discomfort, kidney stones and urinary tracts infections represent some symptoms of this disease [7].
There is no existing cure for renal fusion [7].
Multicystic Dysplastic Kidney (MCDK)
MCDK, a congenital maldevelopment, is the most common type of renal cystic disease. It is characterized by the presence of numerous cysts of multiple sizes replacing what would typically be the renal cortex. Holding the cysts together is a dysplastic parenchyma, containing loose, insubstantial fibrous tissue. No functional renal tissue can be identified. Also, no calyceal drainage system exists in patients with MCDK [10].
In all forms of MCDK, the cysts are lined by squamous or cuboidal epithelium. The dysplastic renal parenchyma consists of immature glomeruli, primitive tubules, and metaplastic cartilage. Fucntional renal tissue within the affected kidney is generally found in the medulla rather than the cortex if present at all. Connecting tubules may provide anatomic communication between the cysts on a microscopic level; however, these connections are not visualized during diagnostic sonography. The size of the cysts and the amount of parenchyma vary in patients with MCDK. The affected kidney may also have a variable blood supply ranging normal to none at all [10].
Typically, MCDK only affects one kidney as persons affected by the bilateral condition die at birth. In the United States of America it is suggested that 1 in 2400 people live births are affected by this disease [10].
