What is the treatment for a dromedary hump on the kidney?

Dromedary Hump on Kidney: No Treatment Required

A dromedary hump is a benign anatomical variant of the left kidney that requires no treatment—only reassurance and, if needed, imaging confirmation to exclude true renal pathology. 1, 2

What is a Dromedary Hump?

A dromedary hump is a prominent focal bulge on the lateral border of the left kidney caused by splenic impression during embryologic development 1, 2. This anatomical variant:

• Exhibits identical imaging characteristics to normal adjacent renal cortex with the same echogenicity, enhancement pattern, and blood flow on Doppler sonography 1, 3
• Is not a tumor, cyst, or pathologic lesion—it is simply normal renal parenchyma shaped by external compression from the spleen 1, 2
• Occurs almost exclusively on the left kidney due to the anatomic relationship with the spleen 2

Diagnostic Confirmation

When a dromedary hump is suspected but differentiation from a true renal mass is uncertain:

• Contrast-enhanced power Doppler ultrasound can definitively demonstrate normal vascular flow pattern identical to adjacent renal cortex, confirming the benign nature 3
• CT urography with contrast shows enhancement identical to normal renal parenchyma in all phases, with no mass effect or distortion of the collecting system 2, 4
• The key distinguishing feature is that dromedary hump enhances uniformly and identically to normal kidney tissue, unlike true renal masses which show different enhancement patterns 1, 3

Management Algorithm

Step 1: Confirm the diagnosis

• If imaging clearly shows a focal bulge with identical characteristics to normal renal cortex on ultrasound, no further workup is needed 1, 2
• If uncertainty exists, obtain contrast-enhanced imaging (CT urography or contrast-enhanced ultrasound) to definitively exclude neoplasm 3, 4

Step 2: Provide reassurance

• Once confirmed as a dromedary hump, no treatment, surveillance imaging, or follow-up is required 1, 2
• This is a normal anatomical variant with zero malignant potential 1, 2

Step 3: Document clearly

• Document the finding as "dromedary hump" or "splenic impression" in the medical record to prevent future unnecessary investigations 2

Critical Pitfalls to Avoid

• Do not biopsy a dromedary hump—it is normal kidney tissue and biopsy carries unnecessary risk 1, 2
• Do not perform serial imaging surveillance—unlike true renal masses, dromedary humps require no follow-up once confirmed 1, 2
• Do not confuse with other renal pseudotumors such as hypertrophied column of Bertin or persistent fetal lobulation, though management is similar (reassurance only) 2, 4
• Recognize that dromedary hump cannot cause symptoms—if a patient has flank pain, hematuria, or other urinary symptoms, investigate other causes rather than attributing them to the dromedary hump 1, 2

Rare Exception: Secondary Polycythemia

In extraordinarily rare cases, a dromedary hump may theoretically contain erythropoietin-producing cells that could cause secondary polycythemia 5. However:

• This is a single case report and the causal relationship remains unproven 5
• If polycythemia is present, exclude all other common causes first (primary polycythemia vera, hypoxia, other renal lesions, hepatic tumors) before attributing it to a dromedary hump 5
• Even in this exceptional scenario, treatment targets the polycythemia (phlebotomy, cytoreduction), not the dromedary hump itself 5