From the Guidelines
A dromedary hump in the kidney is a normal anatomical variant characterized by a bulge or prominence at the superior pole, resembling the hump of a dromedary camel, and is completely benign, requiring no treatment or intervention. This finding occurs due to the normal development of the kidney with extra tissue at its upper portion, creating a distinctive contour. Dromedary humps are most commonly found on the left kidney and result from the normal molding of the kidney against adjacent organs during development. They are often discovered incidentally during imaging studies performed for unrelated reasons, such as those described in the emergency ultrasound imaging criteria compendium by the American College of Emergency Physicians 1. It is essential to distinguish this variant from renal masses or tumors, which would require further evaluation. Radiologists and urologists are familiar with this normal variation and can identify it based on its characteristic appearance on ultrasound, CT, or MRI scans. Some key points to consider include:
- Dromedary humps are a normal anatomical variant and not a pathological condition
- They are most commonly found on the left kidney
- No follow-up imaging or monitoring is typically necessary once it has been identified as a dromedary hump
- It is crucial to differentiate this variant from renal masses or tumors, which would require further evaluation, as variations of renal anatomy, such as reduplicated collection systems, unilateral, bipartite, ectopic, and horse-shoe kidney, can be mistaken for pathologic conditions 1.
From the Research
Definition of Dromedary Hump
- A dromedary hump is a prominent focal bulge on the lateral border of the left kidney, caused by splenic impression 2.
- It is a benign anatomic variant that exhibits the same imaging characteristics as the adjacent renal cortex with a normal blood flow pattern on Doppler sonography 2.
Characteristics and Classification
- Dromedary hump is classified as an anomaly of renal form, specifically a structural anomaly 3.
- It is one of the several renal anatomic variants that can mimic renal neoplasm, including persistent fetal lobulation and hypertrophied column of Bertin 3, 4.
Imaging and Diagnosis
- Ultrasound (US) is usually the first imaging modality used to diagnose dromedary hump due to its low cost, wide availability, and absence of ionizing radiation 3.
- Other imaging methods such as intravenous urography, voiding cystourethrography, CT urography, and MR urography can also be used to characterize the collecting system and demonstrate the function of the kidneys, vascular anatomy, adjacent structures, and complications 3.