Radiology

Case of the Month

Other Cases

Clinical Profile:

A 45 year old farmer presented with complaints of left loin pain and frank hematuria since 10 days. He was a known case of renal calculus disease since 5 years. He gave no history of fever or significant weight loss. He had received treatment elsewhere in the form of blood transfusions and plasma expanders.

Clinical examination revealed a pale patient who had a weak pulse. The abdomen was soft with no tenderness, guarding or rigidity. No lump was palpable.

The hemoglobin was —4.2gm%; urine examination revealed numerous RBCs.

Radiological investigations:

Fig 1	Fig 2
Fig 3	Fig 4
Fig 5	Fig 6
Fig 7	Fig 8

 

The plain film of the abdomen showed multiple left renal calculi (Fig 1).An intravenous urography in addition showed splaying of the calyces of the left kidney (Fig 2).

The ultrasound examination of the abdomen revealed a normal sized right kidney with multiple small hyperechoic well defined lesions seen scattered in the renal parenchyma suggestive of fatty tissue (Fig 3). The left kidney was moderately enlarged with multiple hyperechoic lesions in the upper pole largest measuring 7x6.5x6 cm with ill defined margins (fig 4). This mass appeared to have invaded the renal capsule at the superior pole. There was no calcification seen within the mass. There was a 21mm middle calyceal calculus and multiple small calculi within the middle and lower pole.

In view of incessant hematuria, the patient was taken up for embolisation..

There was a large, inhomogeneous hypervascular mass in the upper pole of the left kidney with a giant (3.8 cm) pseudoaneurysm along one of the intrarenal branches. Some of the interlobular branches were hypertrophied. There were no early draining veins or arteriovenous fistulae seen on angiography (Fig 5)

Embolisation of the upper pole mass and the pseudoaneurysm was done with particulate gelfoam.

Post embolisation left renal angiogram showed obliteration of the hypervascularity and of the aneurysm(Fig 6).

Considering the clinical history, physical examination and investigations the diagnosis of

angiomyolipoma was reached.

Post embolisation the patient improved clinically, his urine was clear within 2 days and his hemoglobin was 9.2gm% on the 5^th day post procedure.

The post embolisation CT scan (Figs 7,8) showed ill defined, irregularly marginated, mixed density lesions with multiple discrete fat density foci within the upper pole of the left kidney with distortion of renal architecture and complete loss of renal outline suggests extension of the neoplastic mass through the renal capsule. Non enhancing hypodensity within the posterior aspect of the mid zone of the left kidney with faint rim of capsular enhancement probably represents post embolisation infarction. Smaller, discrete hypodensities some of which extend through the renal capsule are seen at the lower pole of the left kidney and through out the right kidney suggestive of multicentricity of the tumour.

Discussion:

Renal angiomyolipomas are commonly referred to as hamartomas (a benign growth comprising of abnormal proliferation of tissues normally indigenous to the organ of origin). These tumours comprise of vascular smooth muscle and adipose tissue in variable proportions. Approximately 20% of cases of angiomyolipoma have tuberous sclerosis as an association.

Pathology:

The gross pathology and microscopy of this tumour is determined by the proportion of vascular smooth muscle and adipose tissue present.

The mass may be solitary or multiple, round or oval, with or without lobulations. Multiple masses usually increases the likelihood of associated tuberous sclerosis.

Calcifications are rare (6%)

On cut section—it is yellow to brown in colour.

On microscopy—it may reveal invasion of adjacent structures. It shows fat cells , smooth muscle and areas of tortuous thick walled blood vessels.

Clinical presentation:

Patients with angiomyolipoma fall into three distinct groups:

• those without Tuberous sclerosis
• those with associated Tuberous sclerosis (20% of all angiomyolipomas)
• those with lymphangiomyomatosis

Patients suffering from angiomyolipoma of the kidneys have the following main presenting symptoms:

1. flank pain
2. hematuria
3. shock due to blood loss

Association with the Tuberous Sclerosis (TS) syndrome:

TS is an autosomal dominant disease which was first described by Bourneville in 1888. this disease has am classical triad of

---mental retardation

---epilepsy

---adenoma sebaceum of the face

TS is associated with other CNS and non-CNS manifestations.

CNS:

Cortical tubers

Benign white matter lesions

Subependymal nodules typically located along the lateral ventricles along the striothalamic groove.

Subependymal giant cell astrocytomas (SGCA)

Non-CNS:

Retinal phacomas

Periungual and subungual fibromas involving the toes

Multiple benign renal tumours viz. renal cysts and angiomyolipomas

CVS:

Cardiac rhabdomyomas, vascular ectasias.

Liver:

Leiomyomas and adenomas.

Musculoskeletal system:

Bone islands, periosteal new bone.

Lung:

Cystic lymphangiomyomas.

IMAGING FINDINGS IN ANGIOMYOLIPOMA OF THE KIDNEY

Plain films: If of considerable size, they may be seen as fat lucencies.

Excretory urography—if multiple and large it may be seen as a distortion of the collecting system which is difficult to distinguish from polycystic kidney disease.

USG—it is seen as a hyperechoic structure due to the high content of fat. Intense echogenicity of a renal lesion on ultrasound strongly suggests the diagnosis of angiomyolipoma.

CT scan—the diagnostic CT criterion for angiomyolipoma is visualization of fat density within the lesion. Haemorrhage and other non-fatty components of the mass may also be evident.

MRI—it is seen typically as variable areas of high signal intensity on T1 weighted images.

Angiographic findings—

95% show hypervascularity of interlobar and interlobular branches in the kidney.

Multi sacculated intrarenal aneurysms characterized by the absence of AVM

"sunburst" appearance of capillary nephrogram

"onion-peel" appearance of peripheral vessels in venous phase.

Complications :

1. repeated bleeding
2. haemorrhage into the mass or in the retroperitoneum or into the collecting system leading to hematuria.

Differential Diagnosis :

In the absence of the classical findings of an angiomyolipoma, the following can be the alternative diagnosis.

1. Oncocytoma—it is a frequently encountered type of renal adenoma

These are encapsulated and deep brown in colour. They are more frequent in men and in women (1.7::1). The peak incidence is in the 6^th to 7^th decade. Angiography shows typical "spoke-wheel" appearance of vascularity. There is no AV shunting seen.

2. Wilm’s tumor—a rare differential diagnosis.

Treatment :

Role of vascular intervention

1. prophylactic embolisation of the hypervascular lesion / pseudoaneurysm can be done because hematuria when it occurs can be severe and can lead to shock
2. therapeutic embolisation of bleeding aneurysms in cases who presented with shock.

Surgical treatment is not the treatment of choice since there is extensive involvement of the kidneys and kidney sparing surgery may be difficult.

Home | College | Hospital | Alumni | Contact | Departments | Search | Radiology