Autosomal Recessive Polycystic Kidney Disease is characterized by which of the following?

Autosomal Recessive Polycystic Kidney Disease (ARPKD) is indeed characterized by cystic bilaterally enlarged kidneys with a smooth external surface. This condition is primarily a result of genetic mutations affecting the development of renal tubules, leading to the proliferation of cysts within the renal parenchyma.

In ARPKD, the kidneys typically appear enlarged and smooth externally; the cysts are often microscopic and do not cause an irregular surface unlike in some other kidney diseases. The smooth outer appearance can differentiate ARPKD from other cystic renal conditions, which may show a more lobulated or irregular external morphology.

While the presence of biliary cysts in the liver is associated with ARPKD, it is not a primary characteristic of the disease itself — rather, those cysts can be considered a complication. Kidney stones in the collecting ducts and widespread renal fibrosis and atrophy are also issues that can arise in various kidney diseases, but they are not defining features of Autosomal Recessive Polycystic Kidney Disease. In summary, the defining feature of ARPKD is the presence of the enlarged, smooth kidneys filled with cysts.