Toddler with presumed urinary tract infection

MRI of Wilms tumor
Sagittal US of the left kidney (upper left) shows a round hyperechoic lesion in the lower pole of the kidney. Axial T2 MRI without contrast of the abdomen (upper right) and coronal T1 MRI without (lower left) and with (lower right) contrast of the abdomen shows a well-circumscribed, solid T1 hypointense and T2 isointense mass in the lower pole of the left kidney that enhances minimally.

The diagnosis was Wilms tumor of the left kidney.

Toddler with a fever

US of acute pyelonephritis / acute lobar nephronia
Sagittal US of the right kidney (above) shows an ill-defined hypoechoic mass in the right upper pole that is obscuring the normal outline of the echogenic fat in the renal hilum. The mass was hypoperfused on color and power doppler US. AP image from a voiding cystourethrogram (below) shows bilateral vesicoureteral reflux, grade II on the left and grade III on the right

The diagnosis was acute pyelonephritis in a patient with vesicoureteral reflux.

School ager with bilateral abdominal masses

CT of Burkitt lymphoma of kidney
Coronal T1 MRI without contrast of the abdomen (upper left) shows bilateral enlarged kidneys which after the administration of contrast (upper right) is seen to be due to multiple non-enhancing renal masses. Transverse US of the liver (below) shows a round hypoechoic mass in the liver, superior and to the left of the gall bladder.

The diagnosis was Burkitt lymphoma with renal and liver involvement.

Teenager with an abdominal mass

Axial CT without contrast of the abdomen shows the right kidney to be normal in size and to contain multiple small low density lesions that when measured demonstrate negative Hounsfield units. The left kidney, which is massively enlarged, also contains multiple small low density lesions as well as one extremely large low density lesion in its anterior aspect.

The diagnosis was angiomyolipoma of the kidneys in a patient with tuberous sclerosis.

Female school ager with left lower quadrant abdominal pain and an abdominal mass

US and CT of ovarian dysgerminoma with torsion
Transverse and sagittal US of the pelvis (above) shows an echogenic and inhomgenous solid mass superior to the bladder. Neither ovary could be visualized. Axial CT with contrast of the abdomen shows a solid non-enhancing midline mass. The mass was found to be tossed in the operating room.

The diagnosis was an ovarian dysgerminoma which was found to be torsed in the operating room.