ANGIOMYOLIPOMA

Epidemiology

• The most common benign tumor of the kidney.• 20 to 30 % of angiomyolipomas are associated with Tuberous

sclerosis, and approximately 50% of patients with Tuberous sclerosis develop angiomyolipoma. (Minor et al, 2003)• They are also commonly found in women with the rare lung

disease (lymphangioleiomyomatosis). • consists of thick-walled aneurysmal vessels, smooth muscle,

and varying levels of mature adipose tissue.

Epidemiology

• Angiomyolipoma is now considered to be of neural crest origin, possibly derived from perivascular epithelioid cells (PEC).• Its growth may be hormone dependent, as suggested by its

female predominance and rarity before puberty.• Pregnancy appears to increase the risk of hemorrhage from

AML.

• Associated with Tuberous sclerosis

1. Approximately 20% of patients with AMLs

2. Bilateral, multifocal& large* Tuberous sclerosis (TS) is an autosomal dominant disease

characterized by epilepsy, mental retardation, adenoma sebaceum,

retinal phakomas, and hamartomas of the kidneys, brain,

and other viscera.

Types

• sporadic.(unilateral, unifocal, small, slow

growth rate and are usually detected incidentally)

• Extra renalretroperitoneal lymph nodes, liver,

and spleen have been noted to have AMLs identical to the primary renal tumor. However, these have been

considered to represent multifocality rather than metastases

Tuberous sclerosis

Epilepsy & M.R& Retinal phakomas

Acanthoma sebacum

Hamartoma (renal, hepatic, splenic)

A.M.L

Oncocytoma

R.C.C

Syndome• tuberous

sclerosis•

• Birt-Hogg-Dubé syndrome

• Von Hippel-Lindau disease

features• epilepsy, M.R, adenoma

sebaceum, retinal phakomas& hamartomas of

the kidneys, brain

• familial multifocal oncocytoma.

• cerebellar hemagioblastomas,retinal angiomatosis , pancreatic

tumors or cysts).

Clinical picture (clinical diagnosis is often difficult)

Asymptomatic ( accidentally discovered) 50%1

Flank pain, Flank mass, GIT symptoms (compression)2

Hematuria3

Hemorrhage(hypotension)4

Complications

• The Wunderlich syndrome : massive retroperitoneal hemorrhage, representing the most significant complication of renal angiomyolipoma, was reported in up to 10% of patients and could be associated with significant morbidity and potential mortality if not promptly treated.

• Pregnancy appears to increase the risk of hemorrhage from angiomyolipoma, a factor that can influence clinical decision making.

Diagnosis

1. History taking2. Clinical examination : associated features of T.S, flank mass, hematuria 3. Radiological:

• K.U.B: soft-tissue mass with radiolucent areas in 10%.• U/S : well-circumscribed, highly echogenic (adipose tissue, hge inside the tumour)• I.V.U :unilateral or bilateral space-occupying lesions with distortion of calyces. • C.T :• MRI :T1-weighted image: ↑ signal intensity (due to high fat content)

C.T:(most accurate means of diagnosing an AML)

On cross-sectional imaging. The presence of fat (confirmed on non-enhanced thin-cut CT by a value of −20 Hounsfield Units [HU] or less) within a renal lesion is considered the diagnostic hallmark.

Angiography (CT-angiography):

• aneurysmal dilation is found in 50% of angiomyolipomas. The size of the aneurysms has been reported to correlate with the risk of rupture.

• Renal angiogram shows increased vascularity

and aneurysmal dilation characteristic of angiomyolipoma.

Differential diagnosis

• Solid renal mass : as usual but the challenge is presented with:liposarcoma (compressing the renal parenchyma, not inside the kidney) Possibility of fat-containing RCC (calcifications)possibility of a fat-poor angiomyolipoma resembling an RCC (14% of

cases)• Because of the nonspecific nature of these findings most patients are often

treated as having a presumed RCC. However, these radiographic findings may prompt the attentive urologist to consider a percutaneous biopsy if the suspicion is raised by imaging. Percutaneous biopsy can play an important role in diagnosis in these cases, because a core biopsy should be eminently accurate in the diagnosis of angiomyolipoma

• Positive immunoreactivity for HMB-45, a monoclonal antibody raised against a melanoma-associated antigen, is characteristic for angiomyolipoma and can be used to differentiate this tumor from sarcoma and other tumors

• There’s a reported cases of malignant potentiallity as liposarcoma, fibrosarcoma, liomyosarcoma & it depends on the predominant component

TreatmentTreatment must be individualized, based on the presentation,pregnancy status, tumor size, and renal function.(4-cm cut point)

Nephrectomy

Partial nephrectomy

Large(>8cm)

Medium (4-8cm)A nephron-sparing approach, by either selective embolization or open or laparoscopic/robotic partial nephrectomy, is clearly preferred in patients withPreservation of renal tissue remains a priority in those with TSC or multicentric and particularly in patientswith underlying renal insufficiency.

Small (<4cm) Observation

Embolization

Diagram

complicated

4cm

>8cm

4-8 cm

• Asymptomatic : conservative, (CT / y. for change in size and new lesions).

• followed closely with serial imaging studies, and if significant changes in size or symptoms are noted, or the patient is at risk for flank trauma, elective intervention should be initiated promptly to increase the chances of renal salvage.

• symptomatic (related to pain or bleeding)and should be treated electively prior to the development of symptoms and potential complications.

• Retroperitoneal hge, embolization or surgical

• exploration and nephrectomy

Embolization

• Selective embolization, is reported by some to be the preferred modality, However, a substantial proportion of patients experienced persistent or recurrence of symptoms or hemorrhage and most of these required repeated procedures, including embolization or surgery.

• It should be the first-line therapy in patients with acute or potentially life-threatening hemorrhage, because surgical exploration in this setting is often associated with total nephrectomy

Embolization

• The overall complication rate with embolization in these series was 10% similar to rates of partial nephrectomy and included hemorrhage, abscess formation, or sterile liquefaction of the tumor requiring percutaneous drainage or surgical intervention.

• Also there will be extended follow up which is not required in partial nephrectomy.

Ablative therapy

• Ablative therapies such as radiofrequency ablation and cryoablation have also been utilized for the treatment of angiomyolipoma, but the evaluation of success remains poorly defined. It may have their best role for the treatment of patients with TSC who have multicentric angiomyolipomas or older patients with comorbidities who require treatment and are not candidates for embolization.

Major ts resection (heminephrectomy) Wedge resection Segmental polar

nephrectomy, Simple enucleation

Extracorp. Partial nephrectomy & autoTx

Partial nephrectomy

Prognosis

• Small angiomyolipoma and those without dilated blood vessels (aneurysms) cause few problems, but angiomyolipoma have been known to grow as rapidly as 4 cm in one year. • An angiomyolipoma larger than 5 cm and those containing an aneurysm pose a

significant risk of rupture, which is a medical emergency as it is potentially life threatening.• One study found that the cumulative risk of haemorrhage to be 10% in males and

20% in females.• A second problem occurs when the renal angiomyolipoma take over so much

kidney that the function is impaired leading to chronic kidney disease. This may be severe enough to require dialysis.