A unique case of a mixed epithelial stromal tumor (MEST) that was predominantly composed of adipose tissue is reported here. Radiographically and grossly, the lesion was thought to be an angiomyolipoma, based upon its fatty appearance. Microscopically, the lesion was predominantly composed of mature adipose tissue but also contained clusters of bland tubules surrounded by smooth muscle bundles and collagen. By immunohistochemistry, the stroma labeled diffusely for estrogen and progesterone receptors, while the muscle bundles labeled for desmin. Melanocytic markers HMB45 and Melan A, typically positive in angiomyolipoma, were nonreactive. This case expands the morphologic spectrum of MEST to include mimics of angiomyolipoma.
[Show abstract][Hide abstract] ABSTRACT: Malignant renal tumors constitute 3% of human cancers, although their frequency differs greatly in various areas. Since the fifties, the incidence of renal cancers has been increasing, but at the some time the prognosis has been improving. In particular, in the last years, several new treatment modalities have been introduced, relying on the understanding of renal cancer biology. The identified etiological factors include smoking, increased body mass, dietary factors and chronic renal disease. There are several renal tumor types differing in morphology, molecular genetics and biology. Inactivation of the VHL gene leads to formation of the most frequent form in adults, namely clear cell carcinoma. The VHL gene product, a component of an ubiquitin-ligase complex, regulates expression of several genes. Papillary carcinomas depend mainly on the HGF receptor gene (c-Met) activating mutations. At least two types of papillary carcinomas exist, which have different morphology and prognosis. The molecular biology of chromophobe carcinoma and oncocytoma is poorly understood. Differential diagnosis of these tumors is particularly difficult and may require extensive immunohistochemical and molecular studies. Collecting duct carcinoma and medullary carcinoma are extremely aggressive but rare tumors. Some renal tumors have been described or recognized only relatively recently; these newer entities include multilocular cystic clear cell carcinoma, spindle cell papillary mucinous carcinoma, tubulocystic carcinoma, renal epithelial and stromal tumor, epithelioid and oncocytic angiomyolipoma. Besides histological typing, the prognostic factors include tumor stage, grade and several immunohistochemical and molecular markers that are currently under elaboration. The improved prognosis in renal cancer depends on earlier detection, but also on refinement of therapeutic methods. Small tumors may currently be treated by partial nephrectomy or radiofrequency ablation and larger ones by a laparoscopic approach. All these methods seem to give satisfactory results with low morbidity and mortality rates. Renal carcinoma is notorious for its low sensitivity to chemotherapy and radiotherapy. For several years, immunological treatment with IL-2 and INF-alpha was the only adjuvant therapy method. However, recently several new drugs have been introduced; they act on tyrosine-kinase receptors, VEGF, c-Met or mTOR pathway. With this progress, perfect understanding of renal tumor biology and exact histological diagnosis have become of prime practical importance.
Polish journal of pathology: official journal of the Polish Society of Pathologists 02/2008; 59(3):129-76. · 1.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Juxtaglomerular cell tumors constitute a very small group among the renal neoplasms. Most secrete renin, causing hypertension and hypokalemia due to secondary hyperaldosteronism. They have characteristic pathological features. For the accurate evaluation, diagnosis has to be confirmed by immunohistochemical staining for renin or electron microscopic demonstration of renin protogranules. This report presents a case of renal juxtaglomerular cell tumor in a 63-year-old man with previously unreported histological findings in addition to classic morphology.
International Journal of Surgical Pathology 05/2009; 19(1):65-70. DOI:10.1177/1066896909333416 · 0.95 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Our aim was to review the spectrum of usual and unusual clinical and morphologic findings observed in mixed epithelial and stromal tumor of the kidney (MEST).
On the basis of MEDLINE database searches, we assessed all aspects of MEST or adult mesoblastic nephroma since the first report in 1997 till the end of 2009.
Mixed epithelial and stromal tumor is a relatively rare and distinct neoplasm of the kidney that should be distinguished from other renal neoplasms. Although the overall prognosis is favorable, recurrence and malignant transformation of MEST can occur
It is difficult to distinguish benign or malignant nature on imaging studies.
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