Read all about angiomyolipoma (AML). It is a benign tumor that is a mixture of blood vessels (angio), smooth muscles (myo) and fat (or lipoma). The tumor is seen among Arachnoid granulations.
Angiomyolipomas (AML’s) occur only in the kidneys is not correct. AMLs are benign mesenchymal tumors, composed of blood vessels, smooth muscle, and mature adipose tissue, that arise primarily in the kidneys. AMLs may also occur, however, in extra renal sites, such as the liver, spleen, abdominal wall, retroperitoneum, uterus, oral cavity, penis, spermatic cord, fallopian tube, vagina, skin, and lung.
Majority of cases of Angiomyolipomas of around 85% are widespread and are identified in adults with an average age of 42 years, especially in females. Angiomyolipoma is also a multi-organ benign tumor spread in kidney, lungs and liver.
Angiomyolipomas can cause life-threatening bleeding in 20 percent of cases, explains the Tuberous Sclerosis Alliance. This bleeding occurs because of the abnormal blood vessels within the tumor that cause weak spots within their walls. If these weak spots called aneurysms, burst, bleeding results.
AMLs may also occur in association with other phacomytoses (von Recklinghausen disease, von Hippel-Lindau disease and Sturge-Weber syndrome), autosomal dominant polycystic disease, and pulmonary lymphangiomyomatosis (proliferation of atypical smooth muscle cells of the alveolar wall and perivascular, perilymphatic, and peribronchial regions). Treatment of wide age range of adults and can occur at various locations in the body. But, the most common location is the kidney.
What is Angiomyolipoma?
Angiomyolipoma is a benign renal neoplasm composed of fat, vascular, and smooth muscle elements. It has an incidence of about 0.3-3%. Two types are described: isolated angiomyolipoma and angiomyolipoma that is associated with tuberous sclerosis. Isolated angiomyolipoma occurs sporadically. It is often solitary and accounts for 80% of the angiomyolipomas. The mean age at presentation of patients with isolated angiomyolipoma is 43 years; this neoplasm is about 4 times more common in women than in men. Interestingly, 80% of the cases involve the right kidney. Angiomyolipoma that is associated with tuberous sclerosis accounts for 20% of angiomyolipomas. The lesions are typically larger than isolated angiomyolipomas, and they are often bilateral and multiple. Angiomyolipomas occur in 80% of patients with tuberous sclerosis.
Patients with renal angiomyolipoma often have flank pain, a palpable tender mass, abdominal discomfort, fever, and gross hematuria. Hemorrhage occurs in 15% of angiomyolipomas and in 50% to 60% of tumors larger than 4 cm.
Angiomyolipomas are usually identified when the kidneys are being checked for some other condition. The clinical presentation needing urgent investigation and treatment is spontaneous retroperitoneal hemorrhage. There are also instances of shock as a result of the hemorrhage of the vessels due to Angiomyolipoma. People may experience various other symptoms and signs like:
- Palpable Mass: Asymptomatic tumor can grow into huge mass and may cause symptoms involving pressure on surrounding organ.
- Flank pain caused by pressure on surrounding nerve or expansion of kidney irritating nerves situated around kidney capsule.
- Frequent urinary tract infections
- Microscopic hematuria observed during early phase and frank hematuria is seen during late stage.
- Renal Failure
- Hypertension: increased secretion of angiotensin hormone result in hypertension.
- Anemia: Loss of blood in urine may result in anemia.
The exact cause of angiomyolipoma of kidney is not known but it is believed to develop due as a hereditary trait or may be as a sporadic event. It is a benign tumor that is composed of blood vessels, smooth muscles, fat cells. Majority cases of angiomyolipoma of kidney are sporadic in origin and the rest may be associated with tuberous sclerosis complex, a genetic disorder with mutation of genes occurring on TSC1 and TSC2 gene.
- von Recklinghausen disease (neurofibromatosis type I)
- von Hippel-Lindau disease
- Sturge-Weber syndrome
- Autosomal dominant polycystic kidney disease
- Some reports indicate that events causing a hormonal imbalance in the body, such as puberty and pregnancy in women, may be a risk factor
Angiomyolipoma treatment options vary from one individual to another. The treatment measures for Angiomyolipoma of Kidney may include the following:
Majority of asymptomatic tumors are not surgically removed: The healthcare provider may recommend a ‘wait and watch’ approach for small-sized tumors presenting mild signs and symptoms, after a diagnosis of angiomyolipoma is made
Surgical intervention with complete excision can result in a complete cure. It can also help reduce the chances of tumor recurrence.
The surgical treatment methods for Kidney Angiomyolipomas may include:
- Endoscopic surgery
- Nephron-sparing surgery
- Partial or complete nephrectomy
- Tumor embolization is a possible treatment option
- A partial or complete nephrectomy may be considered, when large-sized tumors are noted in the kidneys. In severe cases of bilateral tumors, kidney transplantation may be necessary.
Newer medical treatments; recently FDA-approved medications may also be used.
A kidney dialysis may be required, if the kidney function is severely compromised due to renal failure
Prompt diagnosis and emergency treatment of any abdominal (retroperitoneal) bleeding due to the tumor should be immediately considered.