A Rare Neoplasm of the Kidney: A Female Patient as the First Case Possibly Triggered by Pregnancy

Mixed epithelial and stromal tumor (MEST) is a rare, biphasic adult renal tumor composed of solid and cystic areas with spindle cell stroma and epithelium.Tumors expressing estrogen and progesterone receptors are affected by hormonal changes, often in post-menopausal women on hormone replacement therapy.Since it can be challenging to differentiate between MEST and malignant tumors, it should be considered as a differential diagnosis.To our knowledge, this is the first case postulated to be caused possibly by pregnancy-related hormonal changes.It is noteworthy that the tumor is affected by changing estrogen and progesterone hormone levels during pregnancy, thus rapidly progressing in a brief time.