Kidney: Metanephric adenoma

2012-09-01   Chin-Chen Pan 

1.Department of Pathology, Taipei Veterans General Hospital, Taipei, Taiwan
2.Department of Pathology, Brigham and Womens Hospital, Boston, MA. pdalcin@partners.org

Summary

Note

A benign renal epithelial tumor resembling differentiation toward early embryonic metanephric tubules.
Atlas Image
Figure 1A Metanephric adenomas are typical, small, well circumscribed with a fleshy tan cut surface (Kelsey McIntyre and Michelle S. Hirsch).
Atlas Image
Figure 1B Histologically, the tumor cells are small, monomorphic and cuboidal. Architecturally, the tumors can demonstrate tubular (predominant), papillary and glomeruloid growth patterns (courtesy Chin-Chen Pan).

Abstract

Review on Kidney metanephric adenoma a, with data on clinics, and the genes involved.

Classification

Note

Metanephric adenoma belongs to the category of Metanephric tumor in the WHO histological classification of tumors of the kidney.

Clinics and Pathology

Etiology

Although previously suggested to be derived from persistent blastema, metanephric adenoma is currently thought to develop from maturation of nephroblastoma.

Epidemiology

Metanephric adenomas are rare (

Clinics

Mostly metanephric adenomas are incidentally discovered. Some patients present with hematuria and abdominal or flank pain.

Pathology

Grossly, metanephric adenomas demonstrate a tan to fleshy white homogeneous cut surface (Fig. 1A) (Grignon et al., 2016). Most tumors are well-demarcated but lack a true capsule and are typically unilateral. Microscopically, the tumor is highly cellular and chiefly composed of tightly packed primitive tubules; papillary or glomeruloid structures may also be seen. The individual tumor cells are small, bland and cuboidal with scant cytoplasm, and round-to-oval nuclei with smooth chromatin, and inconspicuous nucleoli (Fig. 1B). Stromal hyalinization, dystrophic calcification and psammoma bodies are occasionally seen. Metanephric adenomas may resemble nephroblastoma or papillary renal cell carcinoma microscopically. Mitotic figures are rare or absent; necrosis is not seen. Tumor cells are immunoreactive for WT1, PAX8 and BRAF, and are typically negative for CK7 and AMACR.
Atlas Image
Figure 1B Histologically, the tumor cells are small, monomorphic and cuboidal. Architecturally, the tumors can demonstrate tubular (predominant), papillary and glomeruloid growth patterns (courtesy Chin-Chen Pan).

Treatment

Surgical excision.

Prognosis

The vast majority of metanephric adenomas behave in a benign fashion. Cases of regional lymph node metastasis and sarcomatoid changes have been individually reported.

Cytogenetics

Note

No consistent cytogenetic abnormalities have been identified in metanephric adenoma. The gains of chromosomes 7 and 17 noted in papillary renal cell carcinoma, as well as the chromosome gains of 1q, 7q, and 12, and losses of 11p and 16q commonly seen in Wilms tumor have not been detected in metanephric adenoma.

Genes Involved and Proteins

Gene name

BRAF (v-raf murine sarcoma viral oncogene homolog B1)

Location

7q34

Note

BRAF V600E mutations are found in approximately 90% of metanephric adenomas.

Bibliography

Pubmed IDLast YearTitleAuthors
145599912003Metanephric adenoma lacks the gains of chromosomes 7 and 17 and loss of Y that are typical of papillary renal cell carcinoma and papillary adenoma.Brunelli M et al
170988852007Metanephric adenoma of the kidney: a clinicopathological and molecular study of two cases.Burger M et al
227279962012BRAF mutations in metanephric adenoma of the kidney.Choueiri TK et al
86852361996Metanephric adenoma: histology, immunophenotype, cytogenetics, ultrastructure.Gatalica Z et al
93530931997Cytologic and cytogenetic analysis of metanephric adenoma of the kidney: a report of two cases.Granter SR et al
77551481995Metanephric adenoma of the kidney. A clinicopathological, immunohistochemical, flow cytometric, cytogenetic, and electron microscopic study of seven cases.Jones EC et al
116884642001Metanephric adenoma, nephrogenic rests, and Wilms' tumor: a histologic and immunophenotypic comparison.Muir TE et al
164248942006Alpha-methylacyl-CoA racemase as a marker in the differential diagnosis of metanephric adenoma.Olgac S et al
208024692010Detection of chromosome copy number alterations in metanephric adenomas by array comparative genomic hybridization.Pan CC et al
116849652001Metanephric adenosarcoma in a young adult: morphologic, immunophenotypic, ultrastructural, and fluorescence in situ hybridization analyses: a case report and review of the literature.Picken MM et al
251309522015Immunohistochemical staining for BRAF V600E supports the diagnosis of metanephric adenoma.Pinto A et al
107574052000Metastatic metanephric adenoma in a child.Renshaw AA et al
201024002010High-resolution array CGH of metanephric adenomas: lack of DNA copy number changes.Szponar A et al
256027922015Molecular and immunohistochemical characterization reveals novel BRAF mutations in metanephric adenoma.Udager AM et al

Citation

Chin-Chen Pan

Kidney: Metanephric adenoma

Atlas Genet Cytogenet Oncol Haematol. 2012-09-01

Online version: http://atlasgeneticsoncology.org/solid-tumor/5210/kidney-metanephric-adenoma

Historical Card

0000-00-00 Kidney: Metanephric adenoma by  Kelsey McIntyre,Michelle S. Hirsch 

Department of Pathology, Brigham and Womens Hospital, Boston, MA. pdalcin@partners.org