Horseshoe Kidney

horseshoe kidney DMSA

This child was undergoing investigations following a urinary tract infection.

Horseshoe kidney is the most common type of renal fusion anomaly.

It is formed by 2 distinct functioning kidneys on each side of the midline, connected by an isthmus (bridge) of functioning (this case) renal parenchyma or fibrous tissue that crosses the midline of the body.

The fusion is typically between the lower poles (90%). Consequently the inferior poles point medially, which is the reverse of the normal renal axis.

The incidence is approximately 1 in 500.

Complications of a horseshoe kidney include:

1. Hydronephrosis (due to UPJ obstruction)
2. Infection
3. Calculi
4. Increased incidence of malignancy (Wilm’s, transitional cell and carcinoid tumours)
5. Increased susceptibility to trauma (see case – lacerated horseshoe kidney)

References:
eMedicine
ACT Pathology
Chorus

Credit: Dr Ian Bickle