ABSTRACT
Renal angiomyolipoma (R-AML) is one of the most common benign neoplasms of the kidney. It is usually asymptomatic and rarely becomes symptomatic. Management of R-AML is still controversial. Generally, follow-up is enough for the management of the disease but rarely, life-threatening complications may develop. Here, we would like to present a case of huge R-AML with life-threatening bleeding with literature review.
Introduction
Renal angiomyolipoma (R-AML) is a benign mesenchymal neoplasm composed of smooth muscle cells, adipose tissue and thick-walled blood vessels in different compositions. It is usually asymptomatic and found incidentally by routine imaging techniques and rarely becomes symptomatic. The prevalence of R-AML in the general population is between 0.3% and 3% and females are 4 times more at risk than males (1,2). It develops sporadically in 80% of cases and might be a clinical sign of tuberous sclerosis.
We would like to present a patient with giant R-AML which was complicated by life-threatening bleeding into itself spontaneously.
Case Presentation
A 59-year-old male patient presented to the emergency department with abdominal distension, swelling, pain and confusion. There was no trauma or any anticoagulant drug use in the past medical history. Skin color was pale and a solid mass was palpated in the right upper and lower quadrant of the abdomen. His blood pressure was 100/60 mmHg, heart rate - 108 beats/min, hemoglobin (Hb) - 7.1 gr/dL, hematocrit (Htc) - 24%, platelet count - 124000, urea - 45 mg/dL and creatinine was 1.5 mg/dL.
Computed tomography (CT) of the abdomen revealed a 30x25 cm massive lesion originating from the hilum of the right kidney and extending inferiorly and laterally to the right lower quadrant of the abdomen, and including vascular parts in fat tissue. It was considered as a bleeding AML. One hour after the admission to the emergency department, Hb dropped to 6.4 g/dL and Htc dropped to 20.9%. The patient underwent emergency laparotomy due to suspicion of bleeding and the exploration revealed bleeding giant AML originating from the right kidney. Right radical nephrectomy was performed with administering 8 units of erythrocyte suspension and 2 units of fresh frozen plasma. After transferring him to the intensive care unit for 5 days, he completely recovered and was discharged from the hospital pathology showed that the lesion was composed of adipose tissue with proliferative vascular structures and fusiform-cheroot-shaped cells (Figure 1). Immunohistochemical staining for smooth muscle actin showed that fusiform-cheroot-shaped cells were smooth muscle fibers (Figure 2). These areas were also subjected to human melanoma black-45 staining. Vascular structures were stained with CD34. The diagnosis was AML based on the findings.
Written informed consent was obtained from the patient.
Discussion
The term “angiomyolipoma” was first used by Morgan et al. (3) for defining a renal tumor composed of smooth muscle and adipose tissue with different proportions. AML arises sporadically in 80% and accompanies tuberous sclerosis in 20% of cases. Sporadic cases usually seen in females aged 40-70 years and mostly manifest as a large, single and unilateral massive lesion (4). It may also be related with von Hippel-Lindau disease, von Recklinghausen syndrome and polycystic kidney disease (5).
In our case, we evaluated the central nervous system, skin and retina and we did not find any sign related with tuberous sclerosis. Therefore, our case was diagnosed as sporadic AML.
The most important complications seen in patients with AML are retroperitoneal hemorrhage, hematuria and renal failure caused by tumor compression. Sporadic AML is usually asymptomatic and found incidentally as a single mass by renal visualization techniques (6). In our case, the diameter of the mass was 30 centimeters, and this is one of the largest tumors reported in the literature. Renal cell carcinoma, oncocytoma or any other metastatic cancers must be considered in the differential diagnosis. The classical presentation of AML on ultrasonography (USG) is hyperechoic lesion with acoustic ghosting (2,6,7). The most echogenic tumors in all renal tumor types seen on USG are AMLs. CT is the most commonly used imaging technique for the diagnosis of AML (7,8). It is difficult to diagnose AMLs with a small amount of fat using CT or USG (8). In our case, we observed a mass lesion composed of adipose density with vascular structures on CT and it was diagnosed as AML.
The treatment of renal AML is still controversial. For asymptomatic small lesions, follow-up is recommended. Surgical treatment options for AML are radical or partial nephrectomy, selective arterial embolization and ablative methods including cryoablation and radiofrequency ablation. Moreover, a new medical treatment, mechanistic target of rapamycin (mTOR)inhibitors are used for AML related with tuberous sclerosis. Oesterling et al. (9) suggested prophylactic surgery for renal AMLs larger than 4 cm, concomitant with aneurysms larger than 5 mm and AMLs with excessive vascularization due to spontaneous bleeding risk. Selective renal artery embolization or total nephrectomy may be an appropriate option for tumors which are inappropriate for nephron-sparing surgery because of tumor size and location. Following with USG once a year is enough for AMLs which are asymptomatic and smaller than 4 cm (10). Follow-up intervals must be shorter in pregnant patients and those receiving estrogen therapy because there is increased spontaneous rupture risk of AML due to increased estrogen and progesterone receptor expression, maternal circulation and intraabdominal pressure (11). Surgery may be suggested before pregnancy for patients with AML larger than 4 cm or a history of bleeding AML (12).
According to the European Association of Urology guidelines, the most favorable approach to asymptomatic renal AMLs is active follow-up. The first option is selective arterial embolization when any intervention is needed. When the option is surgery, most patients can be treated with nephron-sparing surgery but in some exceptions complete nephrectomy might be a choice. Furthermore, surgery may be delayed if tumor size decreases by mTOR inhibitors (everolimus and sirolimus) (13). In our case, we performed total nephrectomy instead of nephron-sparing surgery because the mass was huge and there was excessive perioperative blood loss.
In fact, our patient received the diagnosis of AML 5 years ago in another clinic but he was not followed. He would not have spontaneous bleeding if the patient had appropriate treatment for 5 years. Prophylactic surgery is the option for AMLs larger than 4 cm or concomitant with aneurysms larger than 5 mm because of the spontaneous bleeding risk (9). We believe that our patient’s hemorrhage was due to an aneurysm rupture because there was no history of trauma or anticoagulant medication use.
As a result, we believe that huge AMLs should be electively treated before the symptoms occur.
Ethics
Informed Consent: Written informed consent was obtained from the patient.
Peer-review: Externally peer-reviewed.
Authorship Contributions
Surgical and Medical Practices: M.Ç., H.D., Ö.E., Concept: M.Ç., H.Ş., Ö.İ.Ç., Design: M.Ç., Ö.E., H.D., H.Ş., Data Collection or Processing: M.Ç., H.Ş., Ö.E., Literature Search: M.Ç., Ö.E., Writing: M.Ç., Ö.E.
Conflict of Interest: No conflict of interest was declared by the authors.
Financial Disclosure: The authors declared that this study received no financial support.
