Renal angiomyolipoma (AML) rarely presents with hemorrhage. We report a case of a large-sized renal angiomyolipoma (12 X 7 X 6.5 cm) with intratumoral and subcapsular spontaneous hemorrhage in a 22-year-old female. The diagnosis was based on radiological features by CT scan and histopathological examination after removal of the tumor. The patient subsequently underwent right nephrectomy. Spontaneous hemorrhage from AML should be expected in large size tumors and fast decision for intervention is mandatory.
Hamdy AbdelMawla Aboutaleb, Mohammed Badr-Eldin
Submitted April 14, 2011 - Accepted for Publication May 19, 2011
KEYWORDS: Angiomyolipoma; Kidney; Hemorrhage
CORRESPONDENCE: Dr. Hamdy AbdelMawla Aboutaleb, Minoufiya University Hospital, Gamal Abdelnasser Street, P. O. Box 32511, Shebin Elkom, Minoufiya, Egypt ().
CITATION: UroToday Int J. 2011 Aug;4(4):art53. doi:10.3834/uij.1944-5784.2011.08.09.
Angiomyolipoma (AML) is a relatively rare benign tumor of the kidney. These are mostly asymptomatic and are discovered incidentally. The imaging features are quite characteristic, and diagnosis can be suspected based on radiological investigations. Although they are mostly asymptomatic, they can be a cause of significant morbidity due to size and hemorrhage . Typically, AML is confined to the kidney but, in rare circumstances, tumor can extend beyond the kidney . We present a case of Angiomyolipoma with a big intratumoral and subcapsular hematoma due to spontaneous hemorrhage.
A 22 years old girl presented to our clinic complains of sudden onset of right loin pain, fullness on the right side of the abdomen. There is no history of trauma or any bleeding disorders. Clinical examination revealed palpable mobile mass in right loin. Vital signs were stable. Laboratory investigations showed severe anemia. Hemoglobin was 6.6g/dl and hematocrit value 25%. Liver and renal functions were within normal limits. Abdominal ultrasonography showed a big hyperechoic mass appearing to arise from the right kidney. Contrast-enhanced CT revealed a well defined large exophytic mass with CT-attenuation value of fat content sized 12 x 7 x 6.5 cm arising from the anterior cortex of the right kidney which measured 8 x 6 x 4 cm with extension to its hilum (Figure 1). Her anemia was corrected before surgery. Patient was prepared for nephrectomy via transabdominal approach and the kidney was removed safely with the huge mass (Figure 2). She had Smooth postoperative course and discharged on the third day.
Histopathology: Specimen after nephrectomy was sent for macroscopic and histopathological examination. A hematoxylin and eosin-stained sections show proliferation of bundles of smooth muscle cells with eosinophilic cytoplasm. These smooth muscle bundles arise from thickened blood vessel walls. Abundant blood vessels were noticed. Also, there is solid sheets and clusters of adipose tissue in between the smooth muscle fibers. Areas of hemorrhage are also seen intratumoral and subcapsular associated with a big subcapsular hematoma (Figure 3).
The overall prevalence of AMLs is approximately 0.3% to 3% so AML of the kidney is quite uncommon. They develop in middle age women and almost 80% of the cases develop sporadically. The other 20% are associated with tuberous sclerosis . Tuberous sclerosis is an autosomal dominant disease tends to occur in younger ages that classically diagnosed as a triad of mental retardation, seizures, and adenoma sebaceum, with AML seen in 80% of the cases. AML in tuberous sclerosis are larger, multiple, and bilateral .
The female predominance in the sporadic form of AML and aggressive nature of the lesion in tuberous sclerosis was explained to be due to progesterone and estrogen receptors in AML found in females and in patients of tuberous sclerosis. This also perhaps explains the rapid growth of AML and higher risk of hemorrhage during pregnancy. The abnormal blood vessels within AML may appear thick and of normal elastin, resulting in formation of aneurysm with increased incidence of hemorrhage. The large size of the mass with predominance of the blood vessels in the present case predispose to spontaneous hemorrhage which threatened the life of the patient. In previous reports, most of the AMLs are smaller than 4 cm, usually asymptomatic, and very unlikely to bleed . However, 80% to 90% of AMLs equal to or greater than 4 cm in diameter are symptomatic, and 50% to 60% of these result in spontaneous hemorrhage . The usual symptoms are flank pain, palpable mass, nausea, vomiting, hematuria, anemia, hypertension, urinary tract infection, shock, or even kidney failure .
AMLs can be diagnosed by various imaging modalities. On ultrasonography, they appear as well-defined and hyperechoic mass, however, they cannot be confidently differentiated from renal cell carcinoma. The detection of fat within the lesion by CT is diagnostic for AMLs. MRI can also demonstrate the intratumoral fat, especially by fat suppression technique. Angiographic findings include cluster of saccular microaneurysms and macroaneurysms, hypervascularity, tortuous vessels. Rarely, the absence of fat, involvement of surrounding structures, and invasion of the inferior vena cava may be seen in angiomyolipoma, making it difficult to be differentiated from renal cell carcinoma. Other rare fat-containing renal lesions such as lipoma, myolipoma, liposcarcoma, oncocytoma, and Wilms tumor may be similar to Angiomyolipoma .
Indications of treatment were pain, haematuria, suspicion of malignancy, large tumor size and spontaneous rupture. Lesions that smaller than 4 cm can be managed conservatively. Nephron sparing surgery was performed for tumors < 4 cm, tumors in a solitary kidney, multiple or bilateral tumors, or in compromised renal function patients. Elective resection is indicated if the risk of hemorrhage appears to be increasing during the follow-up period. However, larger lesions require intervention in the form of intra-arterial embolization, nephron-sparing tumor resection, or depending upon their size and location. More aggressive follow-up and treatment are also necessary during pregnancy, due to hormonal influence on tumor growth and increased risk of hemorrhage [4,5].
In the presenting case, total nephrectomy was performed as it is an indication for tumors ≥ 4 cm or complex renal tumors including completely intrarenal or hilar tumors close to hilar vessels. The tumor in the presenting case was large sized tumor (12 cm X 7 cm X 6.5 cm), arising from the anterior surface and extending to posterior surface reaching the hilum and its origin is very wide base from the anterior and posterior surface and the malignancy was highly suspicious. Intratumoral, subcapsular hemorrhage and extension to the perinephric region was diagnosed by CT scan, moreover; the patient was young with good functioning left kidney without any manifestations of tuberous sclerosis which indicate nephrectomy. Many published reports explained the risk of hemorrhage of renal AMLs especially during pregnancy and in deranged clotting factors [4,5]. We conclude that large size AMLs have the risk of spontaneous hemorrhage and threatening life of patients, so fast elective intervention is strongly indicated.
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