Case Study - July 2012

This 55 year old female was seen in the urology clinic with an incidental finding of a right renal mass
which on CT imaging contains a significant amount of fat.

1) In A and B, what is the diagnosis and what genetic disease can this be associated with?

2) How do they present?

3) What are the indications for intervention in this condition?

She underwent a right laparoscopic nephrectomy. One day after discharge she presented to A&E with nausea, vomiting, abdominal pain and distension. 

4) In C and D, what does her CT show and what is the causative post-operative complication?

Reveal Answer

1) 9cm right renal Angiomyolipoma (AML) arising anteriorly from the upper pole.

Tuberous Sclerosis.

AML is a benign mesenchymal hamartoma composed of a variable proportion of adipose tissue, spindle and epitheloid smooth muscle cells, and abnormal thick-walled blood vessels. Ultrasound, CT, and MRI often lead to the diagnosis due to the presence of adipose tissue.

80% of AML occur sporadically, which is four times more likely in women.

20% of AML occur in Tuberous Sclerosis (TS) when it is multiple, bilateral, larger, and likely to cause spontaneous retroperitoneal haemorrhage (Wunderlich’s Syndrome).

TS is an autosomal dominant condition caused by a mutation of either of two genes, TSC1 (chromsome 9)
and TSC2 (chromosome 16), which code for the proteins hamartin and tuberin respectively. These proteins
act as tumour growth supressors, agents that regulate cell proliferation and differentiation.

Two thirds of cases of TS are found in women, 50% develop AML by the age of 30, 75% are bilateral and 5% of TS patients develop clear cell renal cell carcinomas.

2) AML can present as retroperitoneal bleeding or bleeding into the urinary collection system, which can be life-threatening. However the majority are discovered incidentally or during investigation of TS.

The bleeding tendency is related to the angiogenic component of the tumour that includes irregular and aneurysmal blood vessels. The major risk factors for bleeding are tumour size, the grade of angiogenic component of the tumour, and the presence of tuberous sclerosis.

Current evidence suggests that the majority (up to 70%) of all renal masses are now discovered incidentally. 30% present with symptoms such as pain, heamaturia or a mass. Malignant renal tumours may also present with paraneoplastic syndromes or metastases.

3) Primary indications for intervention include symptoms such as pain, bleeding, or suspected malignancy.

Prophylactic intervention is justifiable for:

•  Large tumours (the recommended threshold of intervention is > 4 cm).

•  Females of childbearing age (increased risk of rupture of AML in pregnancy, mechanism

•  Patients in whom follow-up or access to emergency care may be inadequate.

 Most cases of AML can be managed by conservative nephron-sparing approaches, though some cases of AML may require complete nephrectomy. Of the standard surgical interventions, partial nephrectomy, selective arterial embolisation and radiofrequency ablation can be used. Although embolization is effective at controlling haemorrhage in the acute setting, it has limited value in the longer-term management of AML.

4) Dilated loops of small bowel, one of which has herniated through the rectus sheath on the
right anterior abdominal wall. Subcutaneous pockets of air (surgical emphysema)
consistent with previous laparoscopic surgery.

Laparoscopic port site hernia.

Patients who have had laparoscopic procedures who present with abdominal symptoms may have
an unrecognised intra-operative bowel injury or have developed a port site hernia. However, Ileus is also common, especially after retroperitoneal surgery.

Management of port site hernia initially involves supportive measures including placement of a nasogastric tube. Imaging of choice is CT scanning and treatment involves laparotomy, full inspection of the bowel, resection of any non-viable segments and repair of the hernia.

Ref: Nelson CP, Sanda MG. Contemporary diagnosis and management of renal angiomyolipoma. J Urol 2002 Oct;168 (4 Pt 1):1315-25.

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