American Board of Pathology (ABPath) Practice Test

Cystic kidney diseases in neonates can present in various forms, but multicystic dysplastic kidney (MCDK) is particularly significant due to its distinct characteristics and implications for neonates. MCDK occurs when a kidney does not develop properly during fetal life, resulting in a non-communicating collection of cysts that replace normal renal tissue. This condition is typically unilateral, meaning it affects only one kidney, and the affected kidney is usually nonfunctional.

The diagnosis of MCDK is often made during prenatal imaging, and in many cases, it is discovered incidentally after birth, as it is not always associated with symptoms. The remaining contralateral kidney often compensates, allowing for normal kidney function in affected infants.

Other types of cystic diseases, such as simple cysts, polycystic kidney disease, and autosomal dominant polycystic disease, are less commonly diagnosed in neonates for various reasons. Simple cysts are typically found incidentally and are not usually associated with significant physical findings. Polycystic kidney disease generally presents later in life, particularly in the case of the autosomal dominant form, which typically appears in childhood or adulthood. Autosomal recessive forms can present in infancy but are