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Kidney lipoma is a benign tumor composed of fatty tissue, muscles and blood vessels. The neoplasm originates from the original connective tissue of the organ (mesenchyme). The lipoma is surrounded by a fibrous capsule, this capsule separates the tumor from the kidney itself. Since the lipoma of the kidney, unlike most lipomas of other localization, has blood vessels, it is called an angiolipoma.
The tumor can be microscopic, and can reach very impressive sizes (up to 20 cm in diameter). Kidney lipoma is more commonly diagnosed in women than in men. In 75% of cases, the neoplasm affects only one organ.
Lipoma can develop on the kidney as a single neoplasm, or it can be combined with other tumors or pathologies of the urinary system.
In 88% of cases, kidney lipomas spread beyond the fibrous capsule of the organ. They are able to grow into the renal vein, into the perirenal lymph nodes, into the inferior vena cava.
If the lipoma is growing rapidly, then this is an indication for its emergency removal. Such tumors can pose a threat to human life. In most cases, the patient learns about a lipoma on the kidney by chance, during an ultrasound scan. Until the moment when the tumor reaches a large size, it will exist absolutely asymptomatically.
Causes of kidney lipoma formation
Until now, scientists have not figured out the exact cause of the formation of a lipoma on the kidney. Experts tend to consider this pathology multifactorial, that is, multiple causes will lead to its occurrence.
There are two forms of kidney lipoma:
An isolated tumor that occurs in 90% of cases.
Tumor associated with tuberous sclerosis, which occurs in 10% of cases. This pathology is also called Bourneville-Pringle disease. If the causes of the formation of an isolated lipoma of the kidney remain in question, then the lipoma of the kidney against the background of Bourneville-Pringle disease is a genetic disease. It is inherited in an autosomal dominant manner. The prevalence of the disease among newborns varies from 5 to 7 cases per 100 children. At the same time, patients have multiple bilateral small lipomas on the kidneys, which consist of connective tissues, fat and epithelium. Large lipomas in Bourneville-Pringle disease are diagnosed less frequently.
Scientists suggest that the following factors can play a role in the formation of an isolated kidney lipoma:
Chronic inflammatory diseases of the genitourinary system.
Oncological lesions of the kidneys.
Pregnancy. Angiolipomas in pregnant women develop due to a sharp increase in the level of estrogen and progesterone in the blood.
Exposure to radiation.
Smoking, drug use, alcoholism.
Obesity and diabetes.
Symptoms of kidney lipoma
In the initial stages of development, a kidney lipoma does not give itself away. Moreover, a person can live for many years without knowing about the tumor existing in his body. However, lipoma, like other benign neoplasms, tends to grow slowly, and after reaching a certain size, it begins to give a certain set of symptoms. As a rule, this occurs after the lipoma exceeds 4 cm in diameter.
In this case, up to 80% of patients complain of characteristic symptoms:
Dull lower back pain disturbs up to 44% of them. Pain is caused by the pressure of the tumor on the nerve fibers penetrating the surrounding tissues.
Sharp, sudden pains in the abdomen and in the lumbar region are observed in 56% of patients.
If the tumor reaches an impressive size, it can be palpated.
There may be blood in the urine. Most often, hematuria develops due to compression of the growing tumor of the ureter. At the same time, a person begins to experience pain when emptying the bladder.
Edema of the extremities.
Increase in blood pressure. Against the background of jumps in blood pressure, dizziness, general weakness, and short-term loss of consciousness are observed. A persistent increase in blood pressure is caused by clamping of the veins and arteries that feed the kidney tissue.
When the tumor ruptures, a clinic of an acute abdomen with hemorrhagic shock (severe pain, hematuria, a complex of gastrointestinal symptoms) is observed.
Acute unbearable pain may indicate a kidney infarction or a hemorrhage into the lipoma.
Kidney lipoma can be complicated by rupture of its vessels. This is due to the fact that the muscles grow faster than the blood vessels, although damage to the integrity of the neoplasm capsule is possible even with its small size.
Diagnostics
Lipoma can be detected during an ultrasound examination of the kidneys. It is this method that plays a leading role in terms of detecting neoplasms. During the examination, the doctor visualizes a homogeneous tumor, which is limited to the renal parenchyma. The structure of the renal pelvis will be broken. The degree of impairment depends on the size of the tumor.
Computed tomography for the diagnosis of kidney lipoma is a more informative method. The doctor gets the opportunity to objectively assess the neoplasm. The image will show the structure of the tumor, all the vessels that feed it, areas of high and low density.
MRI of the kidneys is one of the more expensive research methods, so it is used less often when the doctor has doubts about the correctness of the diagnosis. MRI allows you to examine the lipoma in detail in different planes.
Angiography is performed to clarify the vascularization of the tumor. The picture will clearly show the vessels that feed the lipoma. This study is necessary before the upcoming operation.
Needle biopsy is the only method that makes it possible to make a 100% correct diagnosis. Sampling of tumor tissue for histological analysis reveals the nature of the cells and excludes the presence of a malignant tumor. A biopsy is taken only during the operation to remove the lipoma.
Treatment of kidney lipoma
Kidney lipoma does not always require surgical intervention. Often the doctor chooses expectant tactics. Small neoplasms do not disrupt the functioning of the organ, do not provoke the development of complications. Therefore, under the condition of slow growth of the lipoma, dynamic observation is possible. For this, the patient should undergo an ultrasound of the kidneys at least once every six months. It is also important to take a urine test to determine blood impurities in it. The patient must independently control blood pressure. Patients with lipoma of the kidney should have a CT scan performed once a year.
As for drug therapy, it is ineffective in terms of treating kidney lipoma. If the patient is being prepared for surgery, then before it is possible to take drugs that reduce the intensity of pain, as well as drugs that reduce blood pressure.
Surgery is resorted to when the tumor exceeds 4 cm in diameter.
Other indications for surgical removal of the neoplasm:
The rapid increase in lipoma in size.
The development of renal failure.
Lipoma rupture or kidney infarction.
High risk of internal bleeding.
Surgery is the only method that allows you to get rid of the tumor forever.
Types of operations that can be performed to remove the neoplasm:
Resection. During the operation, the surgeon removes only the lipoma itself and part of the organ. Resection can be performed in the classical way, when the doctor makes an incision on the back with a scalpel to gain access to the affected kidney. This procedure is associated with high risks of bleeding and requires a long rehabilitation period. Also, resection can be performed using endoscopic equipment. This is a less traumatic operation in which several small incisions are made.
Nephrectomy. Nephrectomy involves the complete removal of the kidney along with the tumor. This operation is performed when the patient is admitted in a serious condition, for example, when a large lipoma ruptures or when a kidney infarction occurs.
Embolization. This is a new treatment for renal lipoma, which is supplied by blood vessels. During the operation, the doctor blocks the vessel that feeds the tumor. To do this, he injects a special drug into the artery that blocks the lumen of the vessel. The lipoma ceases to receive the substances necessary for its growth and development, which leads to its gradual decrease in size.
Embolization is not used in the case when the lipoma of the kidney is represented mainly by fat cells and has a poor blood supply. In general, as an independent method of treating lipoma, embolization is used extremely rarely. It is indicated for patients with large neoplasms as a preparatory stage for the upcoming resection. By cutting off the supply, the tumor will decrease in size, and then a radical operation can be performed with less loss for the patient.
Prognosis of the disease
The prognosis for patients with kidney lipoma is favorable. The tumor is benign and incapable of malignancy. Most often, it tends to grow slowly, which avoids surgery throughout life.
As for the prevention of neoplasms, there are no specific recommendations on this matter, since the exact cause of the formation of kidney lipoma has not yet been established. Therefore, all the advice that experts give on this subject comes down to maintaining a healthy lifestyle, giving up bad habits and timely treatment of diseases of the urinary system.