benign masses of the kidney

what is the most common benign renal tumor?

angiomyolipoma

angiomyolipoma/renal hamartoma

• consists of a network of blood vessels, muscle and fat

• frequently incidentally encountered

• unilateral and asymptomatic in the general population

clinical findings of angiomyolipoma:

• asymptomatic in most individuals

• patients may have a hx of tuberous sclerosis

• pain, hematuria, and HTN can occur with hemorrhage of the mass

sonographic findings of angiomyolipoma:

• solid, hyperechoic mass

• may produce acoustic shadowing

• tends to be multiple and bilateral with tuberous sclerosis

oncocytoma

• second most common benign renal mass

• difficult to differentiate from an RCC

• often found in men in their 60s

clinical findings of an oncocytoma:

• asymptomatic

• may produce pain or hematuria

sonographic findings of an oncocytoma:

• isoechoic, hyperechoic, or hypoechoic mass

• may also contain a hypoechoic central scar → stellate central scar results from a previous infarction within an oncocytoma

renal hemangioma

• benign mass of blood vessels

• may mimic RCC

clinical findings of a renal hemangioma:

• asymptomatic

• hemorrhage of the mass can lead to pain and hematuria

sonographic findings of a renal hemangioma:

small, hyperechoic mass

renal lipoma

benign fatty tumor most often found in women

clinical findings of a renal lipoma:

asymptomatic

sonographic findings of a renal lipoma:

• well-circumscribed, hyperechoic mass

• usually measures < 5 mm in diameter

renal adenoma

benign mass that appears sonographically similar to RCC

clinical findings of renal adenoma:

• asymptomatic

• may complain of hematuria if tumor is larger

sonographic findings of renal adenoma:

• hyperechoic, vascular mass with internal calcifications

• may produce acoustic shadowing

• typically measure < 1 cm

renal hematoma

localized collection of blood

causes of a renal hematoma include:

• blunt trauma

• surgical intervention or biopsy

• lithotripsy

• rarely, spontaneous hematomas can occur and can be the result of preexisting pathology conditions or may be idiopathic

clinical findings of a renal hematoma:

• hx of some form of trauma to the kidney(s) → blunt trauma, stab wound, biopsy, or lithotripsy

• flank pain

• abdominal pain

• hematuria

• decreased hematocrit

sonographic findings of a renal hematoma:

• variable appearance depending on the stage of the blood and location

• blood may accumulate under the capsule (subcapsular), in the perinephric area (in Gerota fascia), in the pararenal area (anterior or posterior), or intramuscularly (in the psoas muscle)

• chronic hematomas may calcify and produce acoustic shadowing