Multiple renal angiomyolipomata. A case report.

We present a 76-year-old patient with multiple renal angiomylipoma in one kidney. The patient had not been having any urinary tract symptoms, the lesions in kidney were visualized in US examination performed because of cholelithiasis suspicion. Angiomyolipoma is included to the benign tumors of hamartoma group and its growth is related to the hormonal activity of the organism. Multiple renal angiomyolipomata, occurring very rarely, are usually related to the tuberous sclerosis syndrome (Bourneville-Pringle disease). The nature of this disease is the occurrence of multiple hamartoma type tumors in the skin, brain, kidneys, heart, bones, lungs and eyes. Small renal angiomyolipomata are asymptomatic and are usually accidentally diagnosed during imaging examinations, big ones may be the reason of significant ailments. Among severe, life threatening complications of renal angiomyolipoma one can number bleeding from the tumor. Bleeding risk depends on the tumor diameter and significantly increases in tumors of the diameter above 4 cm. Computed tomography is an imaging method recommended for the assessment of hemorrhagic complications in angiomyolipoma. The check-up frequency depends on the tumor diameter - in tumors smaller than 4 cm the examination is performed once yearly, in tumors greater than 4 cm - every 6 months. In the treatment of hemorrhagic complications of angiomyolipoma, a surgical treatment (partial or radical nephrectomy) or renal vessel embolization is used. Renal arteriography with embolization is an important therapeutic method to control the bleeding and to avoid surgery.

Renal angiomyolipoma (AML) is a benign neoplasm included to the hamartoma or choristoma groups. Typically AML contains (in different proportions) the texture of smooth muscle, fatty tissue and blood vessels. Structural changes cause vessel wall thickening and incomplete development of internal elastic lamina which leads to hemorrhagic complications. Another AML type, consisting additionally of perivascular epithelial cells, is more aggressive than the classical form.

AML occurs in 0.3–3% of population (more or less in 1 million of people around the world), more often in women (4:1) which suggests hormonal activity influence on the tumor growth(.

It can occur as an isolated tumor or as a part of the syndrome related to tuberous sclerosis. Tuberous sclerosis complex (TSC, Bourneville-Pringle disease) is a genetic disease with the incidence of 1:10 000– 1:20 000. The nature of TSC are the migration, proliferation and differentiation disturbances. In the course of the disease hamartoma type tumors form. The lesions develop in many organs and may relate to the skin, brain, kidneys, heart, bones, lungs and eyes. The prognosis is serious because 25% of patients die before the age of 10 and 75% – before the age of 25. The cause of death are neurological (central nervous system tumors, epilepsy) and nephrological (kidney insufficiency, kidney cancer, acute hemorrhagic complications) complications, more rarely heart and lungs problems.

In about 80% of cases AML appears as a single lesion, usually in women in the fourth and fifth decade of life. Renal angiomyolipomata related to tuberous sclerosis are usually greater than isolated lesions, occur as multifocal or bilateral lesions, more often in younger patients (in the third decade of life). In case of tuberous sclerosis AML incidence in women only slightly exceeds the incidence in men(.

It has been shown in many studies that the occurrence of symptoms and hemorrhage risk increases with AML size. Three types of hemorrhagic complications can be distinguished: Wunderlich's syndrome (spontaneous retroperitoneal bleeding with no trauma), bleeding or kidney fracture after trauma and kidney fracture during pregnancy (secondarily to hormone activity dependent tumor growth)(.

Nevertheless, the majority of AML does not produce symptoms and is diagnosed in imaging examinations (ultrasound and computed tomography) performed because of other diseases. We present the case of a patient with multiple AML of one kidney who had asymptomatic AML diagnosed in ultrasound examination (US) performed because of cholelithiasis suspicion.

Case report

A 76-year-old patient was referred to the abdominal cavity US examination because of cholelithiasis suspicion. The patient complained of postprandial pain in the right subcostal area. She did not report other ailments. She had not had any diseases.

The presence of fine stones in gallbladder was confirmed in the US examination. The image of the right kidney was normal. In the flesh and renal hilum multiple hyperechogenic focal lesions, of even outline and diameter from 15 to 29 mm were visualized (fig. 1 A, B). Multiple renal angiomyolipomata was diagnosed preliminarily. The patient was referred to the abdominal cavity computed tomography (CT) which confirmed the preliminary diagnosis (fig. 2 A, B). In physical examination and laboratory tests no deviation from normal. The patient remains in outpatient observation.

Fig. 1 A, B

Multiple renal angiomyolipomata in the US image

Fig. 2 A, B

Renal angiomyolipoma in the CT image

Discussion

Usually AML type lesion is diagnosed in the abdominal cavity imaging examination (US, CT) accidentally, during the diagnostic process of other diseases. In the US AML appears as a lesion of high echogenicity (hyperechogenic) of homogenic (mainly in case of larger tumors) or heterogenic echogenicity with no calcifications. It can be difficult to be distinguished from kidney cancer. The diagnosis requires a confirmation in CT examination in which AML appears as a well-defined tumor, containing different amounts of fat and soft tissues (although usually fat dominates). The size of the tumor may oscillate between several millimeters to over 20 centimeters. Only some patients report symptoms characteristic for AML, known as Lenk's triad: lumbar area pain (53%), palpable tumor (47%) and massive hematuria (23%). Other rare concomitant symptoms are: nausea, vomiting, fever, anemia, blood pressure oscillations.

The risk of bleeding increases with the size of a tumor and is estimated for 13% in smaller tumors (up to 4 cm) and 51% in case of tumors of the diameter exceeding 4 cm.

In the majority of patients with lesions up to 4 cm clinical symptoms do not occur – these patients remain in observation and have CT examination performed once yearly.

Asymptomatic AML greater than 4 cm must be regularly – every 6 months – assessed in CT. Clinical symptoms usually appear in AML greater than 8 cm. There is then a significant risk of spontaneous or posttraumatic angiomyolipoma fracture complicated by bleeding. Patients with so big tumors should be qualified for angiography and selective embolization.

In case of chronic bleeding, malignant neoplasm suspicion or embolization failure, the removal of the kidney might be necessary – partial or radical.

Prophylactic embolization in asymptomatic patients, with AML of the diameter 4 cm or greater is recommended in the selected group of high risk patients to which belong women planning a pregnancy and patients for whom the performance or regular checkups might be difficult.

Vessel embolization method is used in kidney tumors as a separate treatment method or, more often, as a preparation for the operative treatment. In case of AML both variants are used. Renal artery embolization in case of AML is recommended in case of bleeding caused by tumor fracture (first choice method). At the same time, embolization causes decrease in tumor size and can be used in case of a sudden hemorrhage as well as a planned therapeutic procedure. Renal artery embolization also enables the performance of conserving surgical procedure(.