The one-hump dromedary camel (Fig. 1) (distinguished from its two-hump Bactrian cousin) provides a descriptive metaphor for a focal contour bulge of the lateral, interpolar aspect of the left kidney. The “dromedary hump”—caused by molding of the normal renal parenchyma by the adjacent spleen [1, 2]—was originally described at excretory urography (Fig. 2), but also can be seen with ultrasound, (Fig. 3), CT, and MR. A common anatomic variant, the dromedary hump should be recognized as a pseudomass, obviating the need for additional unnecessary testing [3]. The “hump” should demonstrate the same imaging characteristics as contiguous normal renal parenchyma, regardless of the imaging modality employed.

Fig. 1
figure 1

Dromedary camel (taken by John O’Neill, used with permission)

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Fig. 2
figure 2

Dromedary hump seen on a urographic image of the left kidney

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Fig. 3
figure 3

Sagittal ultrasound image of the left kidney reveals a focal bulge along the interpolar border that creates the classic “hump.” Note the imaging signature of normal parenchyma, including the hypoechoic medullary pyramid deep to the bulge. The inferior edge of the spleen is seen superiorly, adjacent to the kidney

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