1.
Crossed fused kidney: Like a horseshoe kidney, the two kidneys are fused. Unlike horseshoe, both kidneys end up one side, presenting appearance of a single malformed kidney with two collecting systems. The ureter from the ectopic kidney still inserts in the correct place (that is contralateral)
2:1 male to female ratio
Left-to-right ectopy three times more common.
Normal ascent of the kidneys is required for formation of the extraperitoneal perirenal fascial planes therefore ectopia (or renal agenesis) results in failure of development of fascial layers in the flanks on the side not occupied by renal tissue.
Complications such as nephrolithiasis, infection, and hydronephrosis approaches 50%.
2.
Infantile hepatic hemangioendothelioma: benign endothelial hepatic neoplasm which exhibits rapid growth from birth to 9-12 months.
Most involute spontaneously and slowly without therapy over months to years.
Transformation into a malignant sarcoma is rare.
Most common benign vascular hepatic tumor in the first year of life
Most common symptomatic tumor in the first 6 months of life
Girls > boys.
50% associated with cutaneous hemangiomas. Can be focal, multifocal, or diffuse.
Imaging: well-defined, hypervascular, and large, ranging from 1-20 cm. The descending aorta superior to celiac axis may be enlarged relative to the aorta below the celiac artery secondary to the vascular shunting.
On unenhanced CT, the lesions are of low attenuation although they may be heterogeneous from hemorrhage or calcification. Appearance after contrast enhancement is variable, but early peripheral enhancement is common.
On MRI, hypointense on T1, hyperintense on T2. Hemorrhage and fibrosis can make the attenuation variable. Flow voids can be seen
Clinical: Most are asymtpomatic, especially diffuse type. Can lead to high flow CHF due to shunting. Associated with Kasabach-Merit syndrome. Can compress adjacent vascular structures like IVC. Can overproduce type III iodothyronine deiodinase, which leads to severe hypothyroidism
3.
Nephroblastomatosis: Multiple hypertrophic rests of nephroblastic tissue in the kidneys.
Precursor to Wilms tumore, but most regress
Homogeneous on any scan type
Rind-like subcapsular masses
Hypoenhancing on MR and CT
Otherwise T1 and T2 iso to cortex, isoechoic or slightly hypoechoic on US, iso-dense on CT (detect a trend yet?)
Differential
lymphoma
pyelonephritis
wilms
4.
Sarcoma botryoides: A subtype of embryonal rhabdomyosarcoma, that can be observed in the walls of hollow, mucosa lined structures such as the nasopharynx, common bile duct, urinary bladder of infants and young children or the vagina in females.
Typically younger than age 8
Most common vaginal presentation is bleeding.
