Histopathology Micrograph of a<unk>  (right of image). Normal kidney is seen on the left. Kidney biopsy. PAS stain. Micrograph of a<unk> , right of image, showing the characteristic features (round nuclear membrane, no nucleoli, and fine chromatin). Normal kidney is seen on the left of the image. Kidney biopsy. PAS stain.<unk>  is diagnosed histologically. The tumours can be located at upper pole, lower pole and mid-hilar region of the kidney; they are well circumscribed but unencapsulated, tan pink, with possible cystic and hemorrhagic foci. They show a uniform architecture of closely packed acinar or tubular structures of mature and bland appearance with scanty interposed stroma. Cells are small with dark staining nuclei and inconspicuous nucleoli. Blastema is absent whereas calcospherites may be present. Glomeruloid figures are a striking finding, reminiscent of early fetal<unk>  tissue. The lumen of the acini may contain otherwise epithelial infoldings or fibrillary material but it is quite often empty. Mitoses are conspicuously absent. In the series reported by Jones et al. tumour cells were reactive for Leu7 in 3 cases of 5, to vimentine in 4 of 6, to cytocheratin in 2 of 6, to epithelial membrane antigen in 1 of 6 cases and muscle specific antigen in 1 of 6. Olgac et al. found that intense and diffuse immunoreactivity for alpha-methylacyl-CoA racemase (AMACR) is useful in differentiating renal cell carcinoma from MA but a panel including AMACR, CK7 and CD57 is better in this differential diagnosis. Differential diagnosis may be quite difficult indeed as exemplified by the three malignancies initially diagnosed as MA that later metastasized, in the report by Pins et al. Cytogenetic characteristics Brunelli et al. stated that genetic analysis of chromosome 7, 17, and Y may facilitate discrimination of MA from papillary renal cell carcinoma in difficult cases. Their study showed that MA lacks the frequent gain of chromosomes 7 and 17 and losses of the Y chromosome that are typical of papillary renal cell neoplasms, suggesting that MA is not related to renal cell carcinoma and papillary adenoma.
Metanephric adenoma
Nephrogenic adenoma
Renal medullary fibroma
Renal oncocytoma
Juxtaglomerular cell tumor
Adrenocortical adenoma
Renal cyst
Pituitary adenoma