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AngiomyolipomaAngiomyolipoma

By:Mahmoud Reda

Epidemiology

The most common benign tumor of the kidney. A rare parenchymal renal mass that accounts for

<0.5% of all renal tumors. 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.

Autopsy series and ultrasound-screened populations showed a 0.3% and 0.13% incidence of angiomyolipoma in the general population.

Pregnancy appears to increase the risk of hemorrhage from AML.

Associated with Tuberous sclerosis

Approximately 20% of patients with AMLs have tuberous sclerosis (TS), an autosomal dominant

disease characterized by epilepsy, mental retardation, adenoma

sebaceum, retinal phakomas, and hamartomas of the kidneys, brain,

and other viscera. Bilateral, multifocal& large

Types

• sporadic.(unilateral, unifocal, small, slow

growth rate and are usually detected incidentally)

• Extra renal• retroperitoneal 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 (A.D)

Epilepsy & M.R& Retinal phakomas

Epilepsy & M.R& Retinal phakomas

Acanthoma sebacum

Acanthoma sebacum

Hamartoma (renal, hepatic, splenic)

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).

Remember

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.

Managment

Diagnosis : 1- History taking

2-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.

D.D ????

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

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

complicated

4cm

>8cm

4-8 cm

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.

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