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Cystic angiomyolipoma of the kidney in a patient with chronic renal failure: a very rare variant: Kronik bobrek yetmezligi olan bir hastada bobregin kistik anjiyomiyolipomu:. cok nadir gorulen bir olgu.


Angiomyolipomas are one of the most common types of kidney tumor and can be composed of thick-walled or dysplastic vascular structures, smooth muscle and adipose tissues. (1) Although angiomyolipomas are commonly benign in origin, rare cases of malignant transformation have been reported. (2), (3) Angiomyolipomas are generally identified as solid masses in the kidneys, and the detection of fat by computerized tomography (CT) is commonly observed during radiological evaluation of these lesions. (4) However, some angiomyolipomas may not demonstrate fat content by CT, and these types are referred to as atypical or minimal fat angiomyolipomas. ( 4)

Cystic angiomyolipomas, or angiomyolipomas with epithelial cysts, are extremely rare lesions, and fewer than 20 cases have been reported in the literature according to the Pubmed database. (5-8)

Herein, we report a very rare case of cystic angiomyolipoma of the kidney and discuss the clinical and pathological findings.

Case report

A 62-year-old male patient was admitted to our department with lower urinary tract symptoms. He had a history of right ureterolithotomy and diabetes, although no history of tuberous sclerosis, lymphangiomyomatosis, renal cancer or renal cyst was present. The physical examination was normal apart from the presence of a right flank incision scar. An enlarged benign prostate was detected upon digital rectal examination, and the patient also had chronic renal failure with increased blood urea nitrogen and creatinine levels. The abdominal ultrasound (USG) and CT results revealed a left kidney with a size of 200x77 mm, grade IV hydronephrosis, severe parenchymal loss and a ureteropelvic stone (18x17 mm). A 13-mm ureteropelvic stone and a 2-cm simple cortical cyst were also detected in the right kidney (Figure 1). Dynamic renal scintigraphy demonstrated a non-functioning left kidney. We performed left retroperitoneal simple nephrectomy and double J catheter insertion on the right kidney. The pathologic evaluation of the left kidney demonstrated cystic angiomyolipoma of the kidney (Figure 2). Currently, this patient is tumor-free without any local recurrence.




In general, angiomyolipomas are solid tumors that demonstrate benign behavior. Among the published cases in the literature regarding cystic angiomyolipomas, no cases of malignant transformation have been reported on follow-up, even among patients who had received nephron-sparing surgery. (5-7) Thus, according to the published literature, cystic angiomyolipomas seem to have a benign disease course similar to classic angiomyolipomas. ( 5-8)

The differential diagnosis of cystic angiomyolipomas involves distinguishing between mixed epithelial and stromal tumors (previously classified as cystic hamartomas of the renal pelvis, adult mesoblastic nephroma, or renal pelvic or cortical hamartomas), cystic nephroma, multilocular cystic renal cell carcinoma, liposarcoma and vascular malformations. (7), (8)

Although mixed epithelial and stromal tumors of the kidney are thought to be more common in females (or males with estrogen exposure), (8-10) our patient did not have a history of estrogen exposure. Both cystic angiomyolipomas and mixed epithelial and stromal tumors of the kidney can express estrogen or progesterone receptors, whereas the latter type typically does not express melanocytic markers. (8-10) Cysts lined by epithelium and the surrounding smooth muscle walls are common features of both cystic angiomyolipomas and mixed epithelial and stromal tumors of the kidney. (8)

Previous immunohistochemical studies of cystic angiomyolipomas demonstrated positive staining of the subepithelial stroma with melanocytic markers (HMB-45 and Melan-A), estrogen and progesterone receptors and CD10. (7), (8) Moreover, muscle staining with actin and desmin and cyst lining staining with pancytokeratin were also demonstrated. (7), (8) Of the RCC marker antigens, such as inhibin, WT-1, c-kit (CD117), S-100 protein, and CK20, no positive staining was detected for any of the three components of the tumor (i.e., smooth muscle tissue, blood vessels and mature adipose tissue), and a low proliferative index value was detected according to Ki67 labeling. (7) Therefore, no distinct immunohistochemical staining profile has been identified for cystic angiomyolipomas.

Reported symptoms related to cystic angiomyolipomas include hematuria (microscopic, recurrent or gross), intermittent flank pain, retroperitoneal hemorrhage and acute abdomen due to blood vessel rupture. (5-8) In our case, the patient was diagnosed with cystic angiomyolipoma after being admitted to our outpatient clinic with lower urinary tract symptoms mostly relating to prostatic obstruction.

Although the histogenesis of cystic angiomyolipoma remains unclear, some authors have suggested a role for entrapped renal tubular elements in the etiology of this disease. (6) In our case, no cystic renal cell carcinoma or papillary renal cancer growth was detected upon microscopic evaluation.

In addition, a radiologic follow-up evaluation (abdominal USG and CT) was carried out for our patient due to the presence of a 2-cm simple cortical cyst and urinary tract stone disease.

Conflict of interest

No conflict of interest was declared by the authors.


(1.) L'Hostis H, Deminiere C, Ferriere JM, Coindre JM. Renal angiomyolipoma: a clinicopathologic, immunohistochemical, and followup study of 46 cases. Am J Surg Pathol 1999;23:1011-20. [CrossRef]

(2.) Cibas ES, Goss GA, Kulke MH, Demetri GD, Fletcher CD. Malignant epithelioid angiomyolipoma ('sarcoma ex angiomyolipoma') of the kidney: a case report and review of the literature. Am J Surg Pathol 2001;25:121-6. [CrossRef]

(3.) Martignoni G, Pea M, Rigaud G, Manfrin E, Colato C, Zamboni G, et al. Renal angiomyolipoma with epithelioid sarcomatous transformation and metastases: demonstration of the same genetic defects in the primary and metastatic lesions. Am J Surg Pathol 2000;24:889-94. [CrossRef]

(4.) Kim JY, Kim JK, Kim N, Cho KS. CT histogram analysis: differentiation of angiomyolipoma without visible fat from renal cell carcinoma at CT imaging. Radiology 2008;246:472-9. [CrossRef]

(5.) Davis CJ, Barton JH, Sesterhenn IA. Cystic angiomyolipoma of the kidney: a clinicopathologic description of 11 cases. Mod Pathol 2006;19:669-74. [CrossRef]

(6.) Fine SW, Reuter VE, Epstein JI, Argani P. Angiomyolipoma with epithelial cysts (AMLEC): a distinct cystic variant of angiomyolipoma. Am J Surg Pathol 2006;30:593-9. [CrossRef]

(7.) Armah HB, Yin M, Rao UNM, Parwani AV. Angiomyolipoma with epithelial cysts (AMLEC): a rare but distinct variant of angiomyolipoma. Diagnostic Pathology 2007;2:1-5. [CrossRef]

(8.) Mikami S, Oya M, Mukai M. Angiomyolipoma with epithelial cysts of the kidney in a man. Pathology International 2008;58:664-7. [CrossRef]

(9.) Adsay NV, Eble JN, Srigley JR, Jones EC, Grignon DJ. Mixed epithelial and stromal tumor of the kidney. Am J Surg Pathol 2000;24:958-70. [CrossRef]

(10.) Beiko DT, Nickel JC, Boag AH, Srigley JR. Benign mixed epithelial stromal tumor of the kidney of possible mullerian origin. J Urol 2001;166:1381-2. [CrossRef]


Submitted: 27.08.2010

Accepted: 26.01.2011

Correspondence: Ali Fuat Atmaca

Department of Urology, Ankara Ataturk Training and Research Hospital, Bilkent 06800 Ankara, Turkey

Phone: +90 312 291 25 25


[c] Copyright 2012 by Turkish Association of Urology

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Nevzat Serdar Ugras (1), Ali Fuat Atmaca (2), Abdullah Erdem Canda (2), Mehmet Gumus(3), Mevlana Derya Balbay (2)

(1) Department of Pathology, Selcuk University Selcuklu Medical School, Konya, Turkey

(2) Department of Urology, Ankara Ataturk Training and Research Hospital, Ankara, Turkey

(3) Department of Radiodiagnostics, Ankara Ataturk Training and Research Hospital, Ankara, Turkey
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Title Annotation:Case Report
Author:Ugras, Nevzat Serdar; Atmaca, Ali Fuat; Canda, Abdullah Erdem; Gumus, Mehmet; Balbay, Mevlana Derya
Publication:Turkish Journal of Urology
Date:Jun 1, 2012
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