[Metanephric adenoma of kidney: a clinicopathologic study of eight cases].
OBJECTIVE
To study the clinical and histopathologic features of metanephric adenoma (MA).


METHODS
Eight cases of recently diagnosed MA were retrieved from archival file. Immunohistochemical study was carried out. The clinical characteristics, pathologic parameters, differential diagnosis, treatment options and prognosis of MA were analyzed, with literature review.


RESULTS
The patients included 6 females and 2 males. The age of patients ranged from 12 to 70 years (mean=43.6 years). Eight cases were located in renal cortex and showed well-defined borders. Histologically, the tumor was composed of tubules lined by small basophilic cells and embedded in an edematous stroma. Papillary structures and psammoma bodies were focally seen. Immunohistochemical study showed that the tumor cells were positive for PAX2 and vimentin in all the 8 cases. WT-1 was positive in 2 cases, focal and weak in 5 cases, and negative in 1 case. CK-Pan was positive in 3 cases. CK7 staining was mostly negative, with focal and weak positivity only in 1 case. The proliferative index, as highlighted by Ki-67 staining, was less than 2% in 7 cases and focally around 5% in 1 case. The expressions of CK20, CD10, RCC, epithelial membrane antigen, CD56, synaptophysin and chromogranin A were negative. Follow-up information from 7 to 57 months was available in all patients; and none of them developed local recurrence or distant metastasis.


CONCLUSIONS
The diagnosis of MA relies primarily on thorough histologic examination and immunohistochemical study (vimentin and PAX2 positive, WT-1 focally and weakly positive in some cases, and low proliferative index). Correlation with clinical and radiologic findings would also be helpful.
Department of Pathology, the First Affiliated Hospital of Nanjing Medical University and Jiangsu Province Hospital, Nanjing 210029, China.
Cong
C
Wang
Department of Pathology, the First Affiliated Hospital of Nanjing Medical University and Jiangsu Province Hospital, Nanjing 210029, China.
Guoxin
G
Song
Department of Pathology, the First Affiliated Hospital of Nanjing Medical University and Jiangsu Province Hospital, Nanjing 210029, China.
Mingna
M
Li
Department of Pathology, the First Affiliated Hospital of Nanjing Medical University and Jiangsu Province Hospital, Nanjing 210029, China.
Yan
Y
Zhu
Department of Pathology, the First Affiliated Hospital of Nanjing Medical University and Jiangsu Province Hospital, Nanjing 210029, China.
Weiming
W
Zhang
Department of Pathology, the First Affiliated Hospital of Nanjing Medical University and Jiangsu Province Hospital, Nanjing 210029, China. E-mail: zhangzhihong2001@yahoo.com.
Zhihong
Z
Zhang
Department of Pathology, the First Affiliated Hospital of Nanjing Medical University and Jiangsu Province Hospital, Nanjing 210029, China.
Qinhe
Q
Fan
D000236:Adenoma / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D002292:Carcinoma, Renal Cell / Q000378:metabolism / Q000473:pathology; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000379:methods; D051762:PAX2 Transcription Factor / Q000378:metabolism; D014057:Tomography, X-Ray Computed; D014746:Vimentin / Q000378:metabolism; D025721:WT1 Proteins / Q000378:metabolism; D009396:Wilms Tumor / Q000473:pathology; D055815:Young Adult
D014408:Biomarkers, Tumor; D051762:PAX2 Transcription Factor; C497318:PAX2 protein, human; D014746:Vimentin; D025721:WT1 Proteins