American Board of Pathology (ABPath) 2025 – 400 Free Practice Questions to Pass the Exam

The normal variant characterized by "indentation between the renal calyces giving the kidneys a lobulated appearance" is known as fetal lobulation. This anatomical feature is most commonly observed in the kidneys of children and can persist into adulthood. It is a result of the kidney's development during fetal life when the renal tissue is divided into lobes by interlobar vessels and the renal calyces are positioned between these lobes. These indentations do not indicate any pathological condition; rather, they reflect a benign and normal anatomical variation that can be seen on imaging studies.

Understanding this variant is essential for differentiating it from other renal conditions. For example, a junctional parenchymal defect represents a failure of fusion of the renal lobes and might suggest a more pathological finding, which contrasts with the normal lobulated appearance observed in fetal lobulation. Recognizing fetal lobulation allows for accurate interpretation of kidney imaging and helps avoid misdiagnoses that could lead to unnecessary interventions.