Pure intrarenal lipoma--report of a case and review of the literature

Primary Renal Mesenchymal Neoplasms in Nephrectomy Specimens: A 16-Year Survey of Primary and Incidental Cases From a Single Institution

Context. Primary renal mesenchymal neoplasms are rare but diverse. Several neoplasms of mesenchymal derivation can arise as a primary renal mass; however, incidental tumors are identified in nephrectomies performed for end-stage renal disease or other malignant epithelial renal neoplasms. In this article, we document their frequencies with demographic information in nephrectomy specimens. Design. We retrospectively searched our database for nephrectomy specimens from the year 2000 to 2016. Results. A total of 224 cases were identified with an incidence rate of 4.4% (224/5128). One hundred ninety (85%) neoplasms were benign, 27 (12%) were malignant, and 7 (3%) were of intermediate biologic behavior. The majority of cases occurred in adults (93%, 208/224), and 39% of cases represented an incidental finding. The most common neoplasms were angiomyolipoma (58%) and renomedullary interstitial cell tumor (17%). Malignant mesenchymal kidney tumors are rare (0.39% of nephrectomy specimens). The most common adults' malignant tumors in our survey were synovial sarcoma and Ewing's sarcoma. Conclusion. Primary renal mesenchymal tumors are rare and are mostly benign in nature with many incidentally identified lesions. They arise in different age groups with malignant lesions usually presenting at a younger mean age.

The first case of renal lipoma in a child

Lipoma of the kidney is a rare benign renal tumor that previously had been reported only in adults. We present a case of this tumor in a 2-year-old boy. Serial imaging studies revealed a tumor with high fat content arising from the right kidney. Radical nephrectomy was performed for tumor excision. Macroscopically, the tumor consisted of a yellow fatty mass, which was surrounded by a thin fibrous capsule. The tumor was about 600 g, and the kidney was compressed laterally by the tumor. Microscopically, the tumor consisted of large fat cells that did not express human melanoma black-45 (HMB-45). It was diagnosed as a renal lipoma. Postoperatively, there has been no recurrence of tumor in the 10 months since the surgical excision.

Mesenchymal neoplasms of the kidney in adults: imaging spectrum with radiologic-pathologic correlation

Mesenchymal neoplasms of the kidney in adults cover a wide spectrum with characteristic ontogeny and histologic findings and variable biologic profiles and imaging findings. Benign mesenchymal renal tumors include angiomyolipoma, leiomyoma, hemangioma, lymphangioma, juxtaglomerular cell tumor, renomedullary interstitial cell tumor (medullary fibroma), lipoma, solitary fibrous tumor, and schwannoma. Malignant renal tumors of mesenchymal origin include leiomyosarcoma, rhabdomyosarcoma, angiosarcoma, osteosarcoma, synovial sarcoma, fibrosarcoma, malignant fibrous histiocytoma, and solitary fibrous tumor. Cross-sectional imaging findings for mesenchymal renal tumors in adults are varied. Although angiomyolipomas and lipomas show macroscopic fat, lymphangiomas are cystic in appearance. Renal hemangioma may show phleboliths and a characteristic enhancement pattern. Leiomyoma typically arises from the capsule and causes buckling of the renal cortex. Although osteosarcoma may demonstrate characteristic dense ossification, most renal sarcomas demonstrate imaging features that are indistinguishable from the more common renal cell carcinoma. Although some renal mesenchymal tumors have typical imaging findings, biopsy is warranted to establish a definitive diagnosis. Awareness of the various mesenchymal renal tumors and familiarity with their imaging findings permit optimal patient management.

Huge renal lipoma with prominent hypervascular non-adipose elements

A primary renal lipoma is a very rare neoplasm of the kidney and only 20 cases have been reported in the literature. We report a case of a huge retroperitoneal mass that presented as a hypervascular tumour with a prominent fat component, mimicking an angiomyolipoma or a liposarcoma in imaging studies. This finding presented a diagnostic challenge in terms of selecting medical versus surgical intervention. Surgical excision of the lesions was performed and the pathological evaluation revealed a renal lipoma with extrarenal growth.

Primary Intrarenal Lipoma: A Case Report

Fat-containing tumors of the kidneys are not uncommon, but primary intrarenal lipomas are extremely rare, with only 19 documented cases reported to date. In most cases, total nephrectomy is performed. We report on a 71-year-old man with the complaint of epigastralgia. Series image studies revealed a high fat-containing tumor with low vascularity arising from the lower pole of the left kidney. We performed partial nephrectomy, and the subsequent pathology report revealed a pure lipoma.

Perirenal lipoma versus renal cell carcinoma

Pure renal and perirenal lipomas are rare. They arise from renal cortex, capsule, or perirenal tissue, and may be difficult to distinguish from renal adenocarcinomas. We report on a patient who presented with a renal mass that had the radiologic findings suggestive of a renal cell carcinoma, but proved to be a simple lipoma.

Diagnosis and treatment of renal angiomyolipoma

A series of nine patients surgically treated for histologically verified renal angiomyolipoma is presented. Only one patient had extrarenal stigmata of tuberous sclerosis. No evidence of malignancy was found. In three cases a preoperative diagnosis was achieved with computed tomography (CT), use of which is recommended in evaluation of renal tumours. Six angiomyolipomas were solitary and three bilateral. Abdominal or flank pain was present in eight cases and perirenal haemorrhage in four. Solitary tumours were treated with nephrectomy. For bilateral tumour, nephrectomy and conservative renal surgery were used in two cases and bilateral nephrectomy and kidney transplantation were performed in the third case. When adipose tissue containing renal tumour is demonstrated at CT, conservative surgery should be considered.