Adenoma, metanephric

Metanephric adenoma of the kidney is a unique form of renal adenoma characterized by a proliferation of tubular and micropapillary to glomeruloid structures lined by bland cuboidal epithelial cells. The relatively high nuclear-to-cytoplasmic ratio of metanephric adenoma cells and their slightly amphophilic cytoplasmic coloration impart a typical blue low-power appearance to the neoplastic nodule. The latter is in contrast to the lighter eosinophilic appearance of its main differential diagnosis entity, namely the solid variant of papillary Like papillary RCC, metanephric adenoma can feature foamy histiocytes in papillary cores and occasional psammomatous calcifications. Helpful... 

FIGURE 16.37 Metanephric adenoma (A and B) showing positive nuciear staining for WTl (C) with lack of CK7 expression (D). 

Olgac S, Hutchinson B, Tickoo SK, Reuter VE. Alpha-methyl-acyl-CoA racemase as a marker in the differential diagnosis of metanephric adenoma. Mod Pathol. 2006 19 218. 

Galmiche L, Vasiliu V, Poiree S, et al. Diagnosis of renal metanephric adenoma relevance of immunohistochemistry and biopsy. Ann Pathol. 2007 27 365. 

Muir TE, Cheville JG, Lager DJ. Metanephric adenoma, nephrogenic rests, and Wilms tumor a histologic and immunophe-notypic comparison. Am J Surg Pathol. 2001 25 1290-1296. 

Wilms tumor protein-1 (WT-1) Nephroblastoma, mesothelioma, metanephric adenoma, ovarian serous carcinoma AML, desmoplastic small round cell tumor, endometrial stromal sarcoma, uterine leiomyosarcoma, granulosa cell tumor, thecoma, rhabdoid tumor Kidney, mesothelial cells, granulosa cells, Sertoli cells, fallopian tube endometrial stroma, spleen... 

Metanephric adenoma > 5 years Polycythemia, spontaneous high density, iso-intensity Tl- and T2-WI... 

Fig. 24.19a-c. Metanephric adenoma in a 7-year-old boy. CT scan (unenhanced, a enhanced, b) shows a spontaneously hyperdense small mass. On MR T2-W images (c) the lesion is almost isointense to the normal parenchyma (courtesy Dr. C. Treguier, Hdpital de Pontchaillou, Rennes, France)... 

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