Metanephric Adenoma Torricelli FCM et al. Figure 2 - CT - 4 cm expansive tumoral formation with intermediate attenuation and minimum venous contrast enhan- cing at that anatomic site a-1-antitrypsin, PNA, DBA, SBA and WT-1.2 It seems that, despite the variability, CK7 focally positive is a rule. In our second case, immunohistochemic examination revealed WT-1, EMA and CK7 locally positive. Unlike renal adenoma, which is by definition ,5 mm in diameter, MA can grow to a large size. The diameter of MA 2 ranges from 6 to 200 mm . Our findings were renal tumors of 40 and 45 mm. All MA reported, except one,3 behaved in a benign way with no metastatic findings or local recurrence after surgical removal, showing no evidence of cellular atypical or mitotic activity.2 Similar fact was observed for our two patients. For their special findings in MA variants, some authors deserve brief comment. In 2000, Renshaw et al 3 presented the only reported case of a metastatic disease from a typical MA occurring in a 7 year old child, but no death related to the tumor has been demonstrated. Clinical manifestations related to MA are very unspecific and sometimes even absent, being the majority of these renal tumors incidentally found.4 In 1995, four of eight cases reported by Nonomura et al5 were found with no signs or symptoms and two presented only a tumoral mass. In the same year, Jones et al6 reported one tumor found only at autopsy and six tumors discovered during other pathologi- cal investigation. When present, signs and symptoms include abdominal or flank pain, hematuria, palpable mass, hypertension and fever. Our cases presented some of these clinical findings. At present there are only few reports regarding the imaging findings of MA. Some authors found adenomas to be hyperechoic at USG.7,8 MA has been described to show enhancement on contrast CT, but angiography reveals neither neovascularization nor tumor staining. 7,8 On both T1- and T2-weighted MR images, the tumor is represented as an isointense mass.5,7 On the imaging findings of MA, hypovascularity and frequent calcification may be rather characteristic. Bastide et al9 reported their imaging findings in nine patients, describing MA as a lesion with no vascular flow on color Doppler USG, presence of calcifications, and minimal enhancement in contrast CT. It is possible to realize that MA has same common findings, however none is so specific neither can exclude malignity. Most reports describe total nephrectomy as gold standard treatment for MA, but partial nephrectomy must be considered a good option. Nowadays, it is known that 360 CLINICS 2011;66(2):359-361 Table 1 - MA treatment evolution Author Year Number of cases Surgical Approach kosugi Ebine kumar Batisde 2000 2004 2007 2009 before 2000 1 1 1 9 Open total nephrectomy Open partial nephrectomy Laparoscopic total nephrectomy Laparoscopic partial nephrectomy 4 partial and 5 total nephrectomies partial nephrectomy is indicated even to malignant tumors and even large masses (bigger than 4 cm) can be ressected without prejudice to the oncological results. In 2000, Kosugi et al.10 performed partial nephrectomy for a 32 years old female patient who presented with a right renal MA of 1.5 cm at abdominal USG examination at a routine medical check up. Our two patients were also treated with partial nephrectomy, procedure with better renal function preser- vation, without compromising the patient’s survival. Further advance in reducing patient morbidity may be achieved by laparoscopic nephrectomy as reported by Ebine et al.11 in 2004 for MA treatment in a 31 years old female patient with a left renal mass of 4.5 cm detected incidentally during an abdominal ultrasound examination. Three years latter, Kumar et al12 reported a laparoscopic partial nephrectomy as treatment for MA in a 47-year-old patient. In the biggest MA series reported, Bastide et al9 performed four radical and five partial nephrectomies. In this paper, authors suggest a preoperative diagnostic biopsy, a partial nephrectomy or active surveillance. We believe, that biopsy should be reserved to cases where patient refuse or does not have clinical conditions for surgery or less invasive procedure shall be tried, such as cryotherapy. It is possible to realize that MA treatment has evolved as well as others renal tumors approach, and partial nephrect- omy should be remembered as an option (Table 1). REFERENCES 1. 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Jones EC, Pins M, Dickersin GR, Young RH. Metanephric adenoma of the kidney: A clinicopathological, immunohistochemical, flow cytometric, cytogenetic, and electron microscopic study of seven cases. Am J Surg Pathol. 1995;19:615-26. 7. Araki T, Hata H, Asakawa E, Araki T. MRI of metanephric adenoma. J Comput Assist Tomogr. 1998;22:87–90, doi: 10.1097/00004728- 199801000-00016. 8. Fielding JR, Visweswaran A, Silverman SG, Granter SR, Renshaw AA. CT and ultrasound features of metanephric adenoma in adults with pathologic correlation. J Comput Assis Tomo. 1999;23:441–4, doi: 10. 1097/00004728-199905000-00020. 9. Bastide C, rambeaud JJ, Bach AM, Russo P. Metanephric adenoma of the kidney: clinical and radiological study of nine cases. BJU Int. 2009;103:1544-8, doi: 10.1111/j.1464-410X.2009.08357.x. 10. Kosugi M, Nagata H, Nakashima J, Murai M, Hata J. A case of metanephric adenoma treated with partial nephrectomy. Japanese Journal of Urology. 2000;91:489-92.