Case report Giant renal capsular leiomyoma: study of two cases

The British Journal of Radiology, 77 (2004), 957–958 DOI: 10.1259/bjr/13222406

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2004 The British Institute of Radiology

Case report

Giant renal capsular leiomyoma: study of two cases 1

A M NAGAR, MBBS, DMRD, 1A A RAUT, MBBS, MD, 1R S NARLAWAR, MBBS, DMRD, 2 V L BHATGADDE, MBBS, MD, 2S REGE, MBBS, MS and 2V THAPAR, MBBS, MS Departments of 1Radiology and 2Surgery, K.E.M Hospital, Acharya Dhonde Marg, Parel, Mumbai 400012, India

Abstract. Leiomyomas of the renal parenchyma and of the capsule are rare. These tumours are normally small asymptomatic and often detected incidentally. Large renal leiomyomas can present with pain or as an abdominal mass, but they are rare. The imaging features of these tumours have been poorly described in the literature. A radiological distinction from other renal neoplasms is often difficult to make owing to the similarity of imaging findings. We report two patients with renal leiomyomas who presented with pain and an abdominal mass. Both patients underwent nephrectomy and histological evaluation confirmed the diagnosis of leiomyoma.

Renal leiomyomas in the adult are rare, and found in 5% of autopsy specimens [1]. They may originate from smooth muscle cells in the renal capsule, pelvis, calyx or blood vessels. They are often a few millimetres in size but large tumours can be seen in middle-aged women who may present with abdominal pain [2]. Two cases of large renal leiomyomas are presented.

Case report Case 1 A 34-year-old woman presented with fullness and persistent pain in the left flank. CT revealed an approximately 20 cm large encapsulated, heterogeneously enhancing lesion in relation to the lateral aspect of the left kidney, which was displaced medially and inferiorly by the tumour (Figure 1). There was no evidence of abdominal lymphadenopathy or of involvement of the renal vasculature. At nephrectomy the tumour appeared cystic. Histopathology of the resected specimen identified smooth muscles and connective tissue with areas of myxoid degeneration. The findings were consistent with an encapsulated leiomyoma of the renal capsule.

Case 2 A 30-year-old man presented with a sense of fullness in the flank. A mass was discovered in the right lumbar region. Contrast enhanced CT of the abdomen demonstrated a large mass involving the anterior aspect of the right kidney which enhanced heterogeneously (Figure 2). Fat planes between the tumour and abdominal viscera and major vascular structures were preserved. The patient Received 6 January 2003 and in final form 16 February 2004, accepted 30 March 2004. Address correspondence to: Dr Abhijit A Raut, Department of Radiology, K.E.M. Hospital, Parel, Mumbai 400012, India.

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underwent right nephrectomy. Histological examination confirmed that the tumour was a leiomyoma.

Discussion The mean age of presentation of renal leiomyomas is 42 years [1]. More than 50% of the patients presented with a palpable mass and pain while 20% had haematuria in one series [1]. Steiner et al divided leiomyomas of the kidney into small lesions occasionally found at autopsy and rare large lesions that are symptomatic [1]. Of the lesions that were symptomatic, 53% were subcapsular, 37% capsular and 10% were attached to the renal pelvis. Large lesions over 12 cm in size showed haemorrhage and cystic degeneration [1]. Renal leiomyomas can present with a variety of imaging findings. On ultrasound they present as a solid mass, but cystic changes are not uncommon [4]. CT shows a well-defined mass with heterogeneous enhancement following contrast administration. Leiomyomas of the renal capsule are occasionally attached to the cortex by a small stalk and irregular calcification may be seen [3]. Renal leiomyomas are usually sharply demarcated without infiltration into surrounding tissue or evidence of metastasis. On angiography the tumours do not encase vessels or show evidence of renal vein invasion or of arteriovenous shunting [5]. Leiomyomas that have undergone degeneration may show irregular enhancement along the periphery [6]. The differential diagnosis of a renal leiomyoma includes angiomyolipoma, oncocytoma, renal cell carcinoma and leiomyosarcoma [5]. Angiomyolipomas are fat containing lesions, whereas a central scar with a spoke-wheeled appearance characterizes oncocytomas. Renal cell carcinomas usually have poorly defined edges and may invade adjacent structures. Leiomyosarcomas of the kidney are rarely encountered, and sarcomatous changes of a leiomyoma are difficult to identify on imaging. They are usually peripherally situated, well circumscribed and measure less than 5 cm, and may be resected with an excellent prognosis [1, 7]. Total nephrectomy is indicated for large leiomyomas to avoid the risk of malignancy, necrosis and infection. 957

A M Nagar, A A Raut, R S Narlawar et al

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(b)

Figure 1. (a) Axial contrast enhanced CT shows a large well circumscribed, poorly enhancing lesion arising from the lateral aspect of a medially displaced left kidney. A few foci of enhancement are noted within the tumour. (b) Post-contrast coronal reconstruction shows a well defined large mass displacing the left kidney medially.

References

Figure 2. Contrast enhanced axial CT of the abdomen shows a large mass arising from the anterior aspect of the right kidney. The mass is mainly hypodense but enhancing components are seen along its medial and anterior aspects.

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1. Steiner MS, Quinlan D, Goldman SM, Millmond S, Hallowell MJ, Stutzman RE, et al. Leiomyoma of the kidney: presentation of 4 new cases and the role of computerized tomography. J Urol 1990;143:994–8. 2. Goldman SM, Gatewood OMB. Neoplasms of renal collecting system, pelvis and ureters. In: Pollak HM, editor. Clinical urography. Philadelphia: W B Saunders Company, 1990: 1292–351. 3. Fishbone G, Davidson AJ. Leiomyoma of the renal capsule. Radiology 1969;92:1006–7. 4. Kanno H, Senga Y, Kumagai H, Tanaka Y. Two cases of leiomyoma of the kidney. Hinyokika Hiyo 1992;38:189–93. 5. Hayasaka K, Amoh K, Hashimoto H, Yachiku S. Evaluation of renal and perirenal leiomyoma on US, CT and angiography. Radiat Med 1993;11:81–5. 6. Inoue K, Tsukuda S, Kayano H, Tanaka J, Heshiki A. A case of hypervascular renal capsule leiomyoma. Radiat Med 2000;18:323–6. 7. Mohler JL, Casale AJ. Renal capsular leiomyoma. J Urol 1987;138:853–4.

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