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Saudi Journal of Kidney Diseases and Transplantation
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CASE REPORT Table of Contents   
Year : 2009  |  Volume : 20  |  Issue : 6  |  Page : 1069-1071
A huge renal capsular leiomyoma mimicking retroperitoneal sarcoma

1 Department of Radiodiagnosis, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
2 Department of General Surgery, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
3 Department of Histopathology, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India

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Date of Web Publication27-Oct-2009


A huge left renal capsular leiomyoma mimicking retroperitoneal sarcoma presented in a patient as an abdominal mass. Computed tomography displayed a large heterogeneous retro­peritoneal mass in the left side of the abdomen with inferior and medial displacement as well as loss of fat plane with the left kidney. Surgical exploration revealed a capsulated mass that was tightly adherent to the left kidney; therefore, total tumor resection with radical left nephrectomy was performed. Histopathology ultimately confirmed the benign nature of the mass. This is the largest leiomyoma reported in literature to the best of our knowledge.

How to cite this article:
Lal A, Galwa RP, Chandrasekar P, Sachdeva MS, Vashisht R K, Khandelwal N. A huge renal capsular leiomyoma mimicking retroperitoneal sarcoma. Saudi J Kidney Dis Transpl 2009;20:1069-71

How to cite this URL:
Lal A, Galwa RP, Chandrasekar P, Sachdeva MS, Vashisht R K, Khandelwal N. A huge renal capsular leiomyoma mimicking retroperitoneal sarcoma. Saudi J Kidney Dis Transpl [serial online] 2009 [cited 2023 Feb 9];20:1069-71. Available from: https://www.sjkdt.org/text.asp?2009/20/6/1069/57266

   Introduction Top

Capsular leiomyomas are rare tumours of the kidney. Usually they are very small tumors and do not produce symptoms, thus are detected only on autopsy or as an incidental finding on imaging. Sometime they become large and symp­tomatic and detected as a mass on physical exa­mination as well as on imaging. We are repor­ting a renal capsular leiomyoma, which is to the best of our knowledge the largest size reported in the medical literature.

   Case Report Top

A 45-year-old woman presented with chief complaints of bulging left flank with pain of 6 month duration. Clinical examination revealed a non-tender mass in the left flank. Routine laboratory investigations of blood and urinary examination were within normal limits. Abdo­minal ultrasound revealed a huge mass in the left lumbar region with medial and inferior dis­placement of the left kidney.

A contrast enhanced CT scan revealed a huge heterogeneous mass lesion in the left lumbar region extending superiorly to the upper pole of the spleen and inferiorly to the level of the iliac crest. The left kidney was displaced inferiorly with loss of fat planes and extended to the op­posite side of the abdomen. The small bowel loops were displaced inferiorly to the right side of the abdomen. The tumor showed moderate contrast enhancement with a large central non­enhancing area compatible with necrosis. No evi­dence of fatty attenuation or calcification was seen within the tumor. No retroperitoneal lym­phadenopathy was present [Figure 1],[Figure 2],[Figure 3].

The renal vein and the inferior vena cava were normal. A prospective diagnosis of retroperito­neal sarcoma was considered on imaging. An ultrasound guided fine needle aspiration cyto­logy was inconclusive.

During surgery there was a large encapsulated tumor in the left half of the abdominal cavity, which was tightly adherent to the left renal cap­sule. A radical left nephrectomy was performed along with a total resection of the tumor that measured 32 Χ 25 Χ 12 cm and weighed 3.6 kg.The cut surface of the surgical specimen showed a whorled appearance.

Histopathology revealed a spindle-cell tumor with cells arranged in long fascicles with a fo­cal Herring bone pattern. Thorough examination of the surgical specimen did not show any cyto­logical atypia or mitosis [Figure 4]. The immuno­staining for smooth muscle actin was strongly positive. The tumor was histologically diagnosed as a capsular leiomyoma.

The patient had uneventful postoperative pe­riod and had been disease-free on follow- up for 2 years.

   Discussion Top

Leiomyomas are the most common benign mesenchymal tumors seen in women. They are most commonly located in the uterus and gastrointestinal tract, but they can originate wherever smooth muscle cells exist. Although they have been reported in various atypical localizations, they are extremely rare in the retroperitoneum. Leiomyomas of the kidney are rare mesenchymal tumors. Their frequency in autopsies is from 4.2-5.2% [1] with an average size of less than 5 mm. [2] Clinically apparent leio­myomas are substantially larger but are far less common. These tumors are usually asympto­matic, and when symptomatic they present as a large palpable mass (57%), pain (53%), and mic­roscopic hematuria (20%). Leiomyomas usually present between the 2nd and 5th de-cades of life at a median age of 42 years with a female preponderance (66%). [1] These tumors are com­monly seen in relation to the lower pole of the kidney (74%) with equal incidence in both kid­neys; they can be subcapsular, capsular, or in the renal pelvis, and develop from the renal areas that normally contain smooth muscles, such as renal capsule (37%), renal pelvis (17%), renal cortical vasculature (10%), and indetermi­nate areas. [1]

Imaging studies may demonstrate the retro­peritoneal tumors; however, the exact diagnosis cannot be established by imaging methods alone. Small renal capsular leiomyomas typically appear as well circumscribed masses with homogenous enhancement on contrast enhanced imaging and an occasional cleavage plane between the renal cortex and the tumor. [2],[3],[4] Huge tumors can be­come heterogeneous because of hemorrhage, cystic or myxoid degeneration. [3],[4] They occasio­nally attached to the cortex by a small stalk and irregular calcification may be seen in up to 20% of the cases. [4],[5] When leiomyomas are large and the fat plane is lost in the adjacent structures including renal cortex, a radiological probabi­lity of malignant counterpart i.e. leiomyosarco­mas increases, then it is difficult to differentiate them from other retroperitoneal sarcomas, large exophytic renal carcinomas and angiomyolipo­mas. The role of a percutaneous biopsy to diag­nose such tumors has not been studied in detail; however, it is not always possible to differen­tiate between leiomyoma and leiomyosarcoma based on needle biopsy samples alone. [6]

Total nephrectomy is indicated for large leio­myomas to avoid the risk of necrosis, infection, and malignant degeneration; however, the exact risk is not known. [5]

In conclusion, though establishing the diagno­sis of renal capsular leiomyomas is difficult based on imaging, but it should be strongly con­sidered in the differential diagnosis of a mass, which is closely adherent to the smooth renal outline, and a preoperative biopsy should be performed to prevent radical nephrectomy.

   References Top

1.Steiner MS, Quinlan D, Goldman SM, et al. Leiomyoma of the kidney: Presentation of 4 new cases and the role of computerized tomo­graphy. J Urol 1990;143:994-8.  Back to cited text no. 1      
2.Fishbone G, Davidson AJ. Leiomyoma of the renal capsule. Radiology 1969;92:1006-9.  Back to cited text no. 2  [PUBMED]    
3.Prasad SR, Surabhi VR, Menias CO, Raut AA, Chintapalli KN. Benign renal neoplasms in adults: cross-sectional imaging findings. AJR Am J Roentgenol 2008;190:158-64.  Back to cited text no. 3  [PUBMED]  [FULLTEXT]  
4.Lee SY, Hsu HH, Chang CT, et al. Renal capsular leiomyoma: Imaging features on computed tomo­graphy and angiography. Nephrol Dial Transplant 2006;21:228-9.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]  
5.Nagar AM, Raut AA, Narlawar RS, Bhatgadde VL, Rege S, Thapar V. Giant renal capsular leiomyoma: Study of two cases. Br J Radiol 2004;77:957-8.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]  
6.Silverman SG, Gan YU, Mortele KJ, Tuncall K, Clbas ES. Renal masses in the adult patient: The role of percutaneous biopsy. Radiology 2006; 240(1):6-22.  Back to cited text no. 6      

Correspondence Address:
Ram Prakash Galwa
Department of Radiodiagnosis PGIMER, Chandigarh - 160012
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Source of Support: None, Conflict of Interest: None

PMID: 19861873

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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