Renal Mixed Epithelial and Stromal Tumor
Renal mixed epithelial and stromal tumor is an uncommon complex biphasic neoplasm which occurs in adults.
The tumor comprises less than 1% of all renal neoplasms.
The mean age is around 50 years.
There is a striking female predominance. The tumors are related to hormonal factors (Adsay et al. 2000).
There is no site predominance.
It is typically cured by nephrectomy.
Renal mixed epithelial and stromal tumor is an indolent tumor, although malignant transformation has been reported with a morphology resembling stromal sarcoma and carcinosarcoma (Svec et al. 2001).
The tumor is a solid or solid and cystic mass.
The immunophenothype is characterized by the positive reaction in the stromal component for smooth muscle actin, desmin, estrogen and progesterone receptor, and no staining for inhibin. Nuclear labeling for PAX8 is described in the epithelial component.
It has been reported the association between primary hyperparathyroidism and jaw tumor syndrome (HRPT2 mutation gene) and mixed epithelial and stromal tumor. Gene expression profiles have demonstrated that mixed epithelial and stromal tumors and cystic nephromas clustered together and separated from other renal tumors. Nonrandom X chromosome inactivation (clonal pattern) has been demonstrated in both epithelial and stromal component by using HUMARA.
The main differential diagnosis is cystic nephroma. Because they share some features, some pathologists hypothesized that they represent the opposite ends of the same spectrum proposing the unifying term mixed epithelial and stromal tumor family according to the World Health Organization (WHO) 2016 (Turbiner et al. 2007).
References and Further Readings
- Moch, H., Humprey, PA., Ulbright, TM., et al. (2016) WHO Classification of Tumours of the Urinary System and Male Genital Organs. Lyon.Google Scholar
- Turbiner, J., Amin, M. B., Humphrey, P. A., et al. (2007). Cystic nephroma and mixed epithelial and stromal tumor of kidney: a detailed clinicopathologic analysis of 34 cases and proposal for renal epithelial and stromal tumor (REST) as a unifying term. The American Journal of Surgical Pathology, 31, 489–500.CrossRefGoogle Scholar