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with deep breathing and cough, did not radiate to any part of the body, and was not reduced by any painkiller. The patient had no history of trauma; however, there was a history of diabetes and hypertension treated with aspirin, metformin, glibenclamide, losartan, and amlodipine. Her initial blood pressure and pulse rates were 90/65 mmHg and 118 b/min, respectively. Her body temperature and respiratory rate were normal. The patient's initial hemoglobin was 11.7 g/dL with a white blood cell count, creatinine, and blood sugar of 11400/µL, 0.9 mg/dL, and 236mg/dL, respectively. Nonetheless, her hemoglobin dropped by 2.3 units in the first 24 h.
After IV fluid resuscitation and stabilization, an abdominal and pelvic ultrasound scan was performed which identified mild hydronephrosis in the left kidney with a mass-like lesion measuring 84×90 mm that occupied the upper zone and pelvis of the left kidney. No calcification or vessel flow was observed in the mass. Hyperechoic regions within the mass probably indicated fat tissue suggestive
of angiomyolipoma. Increased mesenteric fat echogenicity was observed around the left kidney, and left perinephric, paracolic, as well as pelvic fluid collections, were observed in this case. The longitudinal diameters of the right and left kidneys were 110 and 124 mm, respectively. The liver, gallbladder, spleen, and pancreas were normal. Abdominal and pelvic CT scan with IV contrast revealed a soft tissue mass consists of fat tissue and blood vessels in the left kidney. The mild right perinephric fluid was also observed, and the adipose tissue inflammation was reported in the left perineal space. Free fluid was noted around the retroperitoneal vessels and the left colon down to the pelvic cavity (Figure 1).
The patient was diagnosed with bleeding due to angiomyolipoma of the left kidney and referred to the surgical ward. She underwent a radical
left nephrectomy due to the diagnosis of angiomyolipoma with active bleeding, followed by decreased hemoglobin and worsening of vital signs. The mass was sent for histological studies, and the diagnosis was confirmed in the histological examination. The patient was discharged in a
good general condition after a few days of hospitalization.
 
Discussion
Angiomyolipoma is a benign tumor consisting of adipose tissue, smooth muscle, and blood vessels. This tumor can be sporadic or associated with tuberous sclerosis. Sporadic cases are within the range of 80-90% and are usually observed in 40-70-year-old females. The tumors in these cases are unilateral and focal; however, in cases associated with tuberous sclerosis, they are bilateral and multifocal and can occur regardless of age and gender. Most patients are asymptomatic, and the tumor is often diagnosed accidentally during an ultrasound or CT scan (9, 11, 12). Common clinical symptoms include flank pain, throbbing mass,
and hematuria. The main complication of angiomyolipoma is bleeding, which is related to the size of the tumor. Increased vascularity and abnormal thickness of the vessel wall predispose the tumor to microaneurysms and bleeding (13). Wunderlich syndrome is a rare syndrome that occurs spontaneously with subcapsular and perirenal space hemorrhage without a history of trauma (14).
In addition to pain, the patient also had urinary and systemic symptoms and was hemodynamically stable upon admission to the emergency department. However, the patients with larger angiomyolipoma tumors and even worse hemorrhagic status presented with only pain or milder symptoms, compared to the patient in our study (15-18). Angiomyolipoma is rarely observed in pregnant females, which can complicate and even terminate the pregnancy(18). Therefore, the size of the tumor or even the presence of an aneurysm or pseudoaneurysm cannot determine the extent of the patient's symptoms. This condition can also cause disorders in laboratory markers, such as leukocytosis and decreased hemoglobin. Similar cases of bleeding of this tumor have been reported in Iran, and the patients' clinical condition was much better than that of our reported case at the time of referral (16). One of the interesting cases of angiomyolipoma in Iran was the appearance of angiomyolipoma after a kidney transplant (17).
Most cases of angiomyolipomas appear as hyperechoic mass containing fat and soft tissue in ultrasound studies. However, the hyperechoic findings are not specific for angiomyolipomas and can be found in other kidney tumors, including renal cell carcinoma, liposarcoma, and atypical Wilms tumor. The CT scans are very specific and show adipose tissue in the lesion, which confirms the diagnosis (8, 19). A magnetic resonance imaging along with a fat suppression technique can detect fat tissue inside the tumor. Angiographic findings include saccular micro and macro aneurysms, hypervascularity, and tortoiseshell arteries. The absence of adipose tissue in the tumor, surrounding soft tissue involvement, and inferior vena cava invasion can rarely be noted in angiomyolipoma, which makes it difficult to differentiate from renal cell carcinoma (20). However, there have been rare reports of renal cell carcinoma containing fat tissue. Calcification has been observed in these cases
(21), wheras angiomyolipoma rarely contains calcification (22). It may be difficult to differentiate large angiomyolipoma from liposarcoma since both of them contain fat. The evaluation of renal parenchyma defects and the presence of large arteries can help differentiate angiomyolipoma from liposarcoma (23). Angiomyolipoma tumors with pain, hematuria, suspected malignancy, large tumor size, and spontaneous rupture should undergo surgery. In sporadic angiomyolipoma, follow-up with ultrasound or CT scan should be considered if the tumor size is less than 4 cm (24). However, embolization angiography may be performed in cases with mild bleeding and stable hemodynamics (1).
 
Conclusion
Angiomyolipoma can be presented with sub-capsular and perirenal hemorrhage with no history of trauma that can be life-threatening 
 
Acknowledgments
The authors would like to express their gratitude to Dr. Enayatollah Noori, for  their useful help.
 
Conflict of interest
The authors  declare  that  there  is  no  conflict  of interest