Benign Mixed Epithelial and Stromal Tumor of the Kidney With Cytogenetic Alterations—Advances and Controversies in Classification of Biphasic Cystic Renal Tumors

We present a case of benign mixed epithelial and stromal tumor of the kidney (MEST) with some unusual features, such as a partially exophytic growth, relatively solid tumor architecture, and negative stains for estrogen/progesterone receptors. We also report the results of cytogenetic studies and discuss the differential diagnosis of the MEST family of tumors in the context of other biphasic cystic renal lesions. Based on the molecular studies thus far published, MEST and adult cystic nephroma are similar to each other but different from other kidney lesions, including morphologically similar cystic and biphasic pediatric lesions. The discovery of the molecular signatures of several cystic renal lesions has led to their proper classification. However, with regard to the MEST family of tumors, the search for a “signature” molecular abnormality continues, and at present, molecular studies focus on the exclusion of abnormalities diagnostic of morphologically overlapping lesions. At present, patient age seems to be the most useful factor in the classification of morphologically similar lesions. Although the term mixed epithelial and stromal tumor family is all inclusive, retention of the term cystic nephroma, for both pediatric and adult lesions, will continue to create confusion. Although most MEST lesions are benign, caution is advised in the management of patients with limited tumor sampling, such as occurs in core biopsy or cytology. It is also prudent to ensure adequat...
Source: Pathology Case Reviews - Category: Pathology Tags: Case Reviews Source Type: research