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Year : 2020  |  Volume : 63  |  Issue : 3  |  Page : 460-462
Aggressive angiomyxoma of renal pelvis in a horseshoe-shaped kidney: Rare tumor at an unusual site

1 Department of Pathology, Maulana Azad Medical College, New Delhi, India
2 Department of Surgery, Maulana Azad Medical College, New Delhi, India

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Date of Submission28-Jan-2019
Date of Decision06-Sep-2019
Date of Acceptance07-Sep-2019
Date of Web Publication7-Aug-2020


Mesenchymal neoplasm is rare in renal pelvic region. Aggressive angiomyxomas are the neoplasms seen predominantly in female genital region. These tumors are locally aggressive with rare cases presenting with metastasis. Its occurrence in renal pelvis is extremely rare with only five cases reported in the literature. The present case is the sixth case reported in a 15-year-old girl who presented to the surgery department as a case of horseshoe kidney. The mass was excised and a diagnosis of aggressive angiomyxoma was rendered.

Keywords: Aggressive angiomyxoma, horseshoe kidney, renal pelvis

How to cite this article:
Sagar N, Arora P, Khurana N, Agarwal P N. Aggressive angiomyxoma of renal pelvis in a horseshoe-shaped kidney: Rare tumor at an unusual site. Indian J Pathol Microbiol 2020;63:460-2

How to cite this URL:
Sagar N, Arora P, Khurana N, Agarwal P N. Aggressive angiomyxoma of renal pelvis in a horseshoe-shaped kidney: Rare tumor at an unusual site. Indian J Pathol Microbiol [serial online] 2020 [cited 2022 Sep 30];63:460-2. Available from:

   Introduction Top

Mesenchymal lesions in perirenal region are uncommon. Aggressive angiomyxoma is seen predominantly in female population with genital region being the commonest site. Its occurrence in renal pelvis is unusual and has been reported only 5 times in the literature. The tumor is locally infiltrative with high chances of recurrence and can rarely metastasize.[1],[2] We report a case of aggressive angiomyxoma of renal pelvis in a 15-year-old patient with horseshoe kidney.

   Case History Top

A 15-year-old girl was admitted with the complaints of pain in left flank region associated with burning micturition since 3 months. MRI performed showed that left horseshoe kidney showing hydronephrotic changes, with a homogenous soft tissue mass measuring 6 × 4.5 × 3 cm involving the renal hilum, pelvis, and para aortic region [Figure 1]. A differential diagnosis of lymphoma was rendered based on radiological findings. The mass was excised and sent to histopathology department of our hospital. Gross specimen consisted of a tumor measuring 5 × 4 × 2.5 cm with attached ureter measuring 2 cm in length. On cut section, the tumor was homogenous white and appeared translucent gelatinous with multiple tiny foci of congestion. Multiple thin sections were taken and whole specimen was processed. Histopathological sections revealed predominantly large areas of myxoid stroma admixed with few spindle to ovoid plump cells intermixed variable sized, predominantly capillary vessels and few adipocytes [Figure 2] and [Figure 3]. No significant mitosis, atypia, areas of hemorrhage, or necrosis were seen. No lipoblasts were seen. Other differentials considered were dedifferentiated liposarcoma, angiomyolipoma, myxoma, and myxofibrosarcoma. On immunohistochemistry: S-100 was negative, HMB-45, vimentin positive in stromal cells. Margins were clear and resected end of ureter was free from involvement. Based on the morphological findings, a diagnosis of aggressive angiomyxoma was rendered. The patient is on follow-up and remains disease free for the past 2 years.
Figure 1: Left horseshoe kidney showing hydronephrotic changes, with a homogenous soft tissue mass involving the renal hilum

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Figure 2: Myxoid stroma admixed with spindle to ovoid plump cells intermixed with capillary-sized vessels with overlying smooth muscle (H/E, 200×)

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Figure 3: Areas of myxoid stroma admixed with few spindle to ovoid plump cells intermixed with capillary-sized vessels (H/E, 400×)

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   Discussion Top

Aggressive angiomyxoma first described by Rosai and Steeper in 1983 is an uncommon neoplasm, mostly seen in vulval and perineal region in females. The tumor shows strong predilection for females with female: male ratio being 6:1. It is a slow growing tumor with higher rate of recurrence, hence, termed aggressive. The tumor can involve surrounding structures rapidly and can cause local symptoms; however, metastatic spread is rare.[3] Its occurrence in kidney is unusual and has been described only 5 times. Out of these five cases, three cases occurred in post renal transplant patients, while two presented de novo.[4],[5],[6] Ours is the third such case with no significant prior history. Histopathological diagnosis of angiomyxoma remains challenging. The differential diagnosis included dedifferentiated liposarcoma, myxoma, and myxofibrosarcoma. Dedifferentiated liposarcoma may be differentiated by the absence of atypical lipoblasts. Myxoma does not show the presence of vascular channels as seen in angiomyxoma.[7] In perineal region, differentiation from angiomyomyfibroblastoma is challenging. Although few cases of perirenal angiomyolipoma have been described in the literature,[8] the tumor did not show smooth muscle component or thick-walled vessels and was negative for HMB-45.

There is no specific marker for aggressive angiomyxoma. On immunohistochemistry, the tumor cells can show positivity for vimentin, estrogen, and progesterone. The cells within the stroma may show positivity with desmin, CD34, and actin.[9] Some cases have shown chromosomal translocations involving 12q13-15 (the high mobility group A [HMGA2] gene).[10] The best course of treatment remains local excision with negative margins, and regular follow-up to look for recurrence.

Renal aggressive angiomyxoma is an extremely rare tumor with only few cases described in the literature. Radiological findings may be confusing mimicking malignancy. Histopathological examination remains gold standard for diagnosis. Timely excision and diagnosis is essential to maintain renal functionality and avoid more aggressive approach.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Siassi RM, Papadopoulos T, Matzel KE. Metastasizing aggressive angiomyxoma. N Engl J Med 1999;341:1772.  Back to cited text no. 1
Blandamura S, Cruz J, Faure Vergara L. Aggressive angiomyxoma: A second case of metastasis with patient's death. Hum Pathol 2003;34:1072-4.  Back to cited text no. 2
Mathieson A, Chandrakanth S, Yousef G. Aggressive angiomyxoma of the pelvis: A case report. Can J Surg 2007;30:228-9.  Back to cited text no. 3
Gorsi U, Naranje P, Rathi M, Nada R, Khandelwal N. Aggressive angiomyxoma of transplanted kidney mimicking posttransplant lymphoproliferative disorder. Saudi J Kidney Dis Transpl 2017;28:425-7.  Back to cited text no. 4
[PUBMED]  [Full text]  
Salehipour M, Geramizadeh B, Azizi V, Rajabi MJ, Boub R. Renal Angiomyxoma. Saudi J Kidney Dis Transpl 2006;17:576-7.  Back to cited text no. 5
[PUBMED]  [Full text]  
Gondo T, Takahashi M, Hoshii Y, Iwata T, Kashiwagi T, Ishihara T. Angiomyxoid tumour in the renal peripelvic tissues with features of aggressive angiomyxoma. J Clin Pathol 1995;48:82-3.  Back to cited text no. 6
Idrees MT, Hoch BL, Wang BY, Unger PD. Aggressive angiomyxoma of male genital region. Report of 4 cases with immunohistochemical evaluation including hormone receptor status. Ann Diagn Pathol 2006;10:197-204.  Back to cited text no. 7
Ditonno P, Smith RB, Koyle MA, Hannah J, Belldegrun A. Extrarenal angiomyolipomas of the perinephric space. J Urol 1992;147:447-50.  Back to cited text no. 8
Sutton BJ, Laudadio J. Aggressive angiomyxoma. Arch Pathol Lab Med 2012;136:217-21.  Back to cited text no. 9
McCluggage WG, Connolly L, McBride HA. HMGA2is a sensitive but not specific immunohistochemical marker of vulvovaginal aggressive angiomyxoma. Am J Surg Pathol 2010;34:1037-42.  Back to cited text no. 10

Correspondence Address:
Nishant Sagar
Department of Pathology, Maulana Azad Medical College, New Delhi - 110 002
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJPM.IJPM_74_19

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