Renal Neoplasms and Congenital Renal Structures

Horseshoe Kidney

• Most common of all renal fusion abnormalities
• 90% of fusions happen at the lower poles of the kidneys
• Fusion takes place around gestational week 7 in utero
• May present with other genital abnormalities such as hypospadias, undescending tests, bicornuate uterus, or septate vagina
• Common findings include issues with the urinary collecting system (ureteral duplication, UPJ obstruction, and vesicoureteral reflux)
• Vesicoureteral reflux increases the risk of UTIs
• May present in patients with Turner's syndrome, Trisomy 13, 18, or 21
• Most patients do not have symptoms
• Found at 18-20 weeks gestation during an anatomy ultrasound
• CT urography is the best test for detection
• VCUG is the best test for urinary reflux
• Two times increased incident of Wilm's tumor in patients with a horseshoe kidney

Hydronephrosis

• When urine backs up into the kidney leading to kidney swelling
• Patients are commonly asymptomatic, but may present with pain in the flanks, abdomen, or groin
• May have hypertension due to the kidney's activation of the RAAS
• Will have a normal urine analysis
• Seen on ultrasound
• CT scan should be ordered if concerned about kidney stones as the cause
• Most common cause is a kidney stone (especially stones larger than 10 mm)
• Scar tissue and adhesions from previous urinary system surgeries can also cause hydronephrosis

Polycystic Kidney Disease (PKD)

• Due to cyst formation from the nephrons that grow outward
• Autosomal dominant mutation in either PDK1 or PKD2
• More severe PKD is from a mutation in PDK1
• Multisystem disorder that commonly impacts the liver, spleen, pancreas, heart, and brain
• Liver is the most commonly impacted organ
• Typically found in patients in their 30-40s with a family history
• Patients complain of abdominal pain, flank pain, nephrolithiasis, UTI, and hematuria
• Urine analysis shows hematuria, decreased urine concentration, and proteinuria
• Diagnosed with ultrasound
• Managed based on the number of cysts present
• Patients should be referred to a nephrologist

Renal Vascular Disease – Renal Artery Stenosis

• Most common cause of secondary hypertension
• Should be suspected if a patient has uncontrolled hypertension or unexplained creatinine elevate
• Can cause asymmetry in kidney size with one kidney being more than 1.5 cm larger than the other
• Patients likely have blood pressures above 160/100 after the age of 55
• CT angiography or MR angiography are the first-line imaging modalities
• Renal catheter arteriography is the definitive diagnostic test
• Definitive management is revascularization
• Patients with bilateral renal artery stenosis or only one kidney that has renal artery stenosis should not take ACEi or ARBs, it is contraindicated

Renal Cell Carcinoma

• Tumor of the proximal convoluted renal tubules
• Around 95% of primary tumors originate in the kidney
• Smoking is a major risk factor
• Most common location of metastasis is the lungs, which looks like a “cannon ball” on imaging
• Classic triad of symptoms: hematuria, flank or abdominal pain, and a palpable abdominal mass
• Patients experience malaise and weight loss
• Paraneoplastic syndrome, including hypercalcemia and cachexia, is common
• Stauffer Syndrome is hepatic dysfunction in the absence of liver tumors due to cytokine release
• CT scan is the initial imaging test
• PET scan can be used to evaluate for potential metastases in other organs
• Definitive diagnosis is tissue biopsy
• Main treatment is radical nephrectomy

Wilms Tumor

• Nephroblastoma
• Most common renal malignancy in children and most common cause of abdominal masses in children
• Presents at ages 0 to 5 years
• Present with a palpable abdominal mass, abdominal swelling, and pain
• Associated with WAGR syndrome (deletion on chromosome 11), Denys-Drash syndrome, and Beckwith-Wiedemann syndrome
• Best initial test is an abdominal ultrasound
• CT with contrast or MRI is the most accurate imaging test
• Has a high cure rate when managed with a total nephrectomy followed by chemotherapy