Imaging Pearls ❯ Kidney ❯ MEST
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- Mixed Epithelial and Mesenchymal Neoplasms: Facts
- Consists of mixed epithelial and stromal tumors (MEST) and cystic nephromas
- MEST was previously called
--- Leiomyomatous renal hamartoma
--- Multilocular cyst with ovarian stroma
--- Cystic hamartoma of the renal pelvis
--- Adult mesoblastic nephroma - MEST (Mixed epithelial and stromal tumor of the kidney)
Mixed epithelial and stromal tumor (MEST) is a rare benign renal neoplasm composed of epithelial and stromal component and shows variable solid and cystic areas. Along with adult cystic nephroma, it is included in the family of mixed epithelial and stromal tumor in the 2022 WHO classification of renal neoplasms. Most tumors are benign; however, they may recur if incompletely excised. Rare examples of malignant transformation of the epithelial or stromal component have been reported. - MEST (Mixed epithelial and stromal tumor of the kidney)
- The majority of diagnosed tumors occurred in women at menopausal age and females affected ten times more than males
- age of diagnosis varied from 17 to 78 years old and most commonly being in 5th decade.
- clinical presentation of MEST may include flank pain, blood in urine, urinary tract infections and abdominal mass - MEST (Mixed epithelial and stromal tumor of the kidney)
- MEST usually presents as unilateral and solitary kidney lesions. Usually the tumor is well-demarcated, triphasic CT scan commonly reveals complex cystic lesions, described as III or IV in the Bosniak classification, with solid components and contrast enhancement
- The majority of MESTs are benign lesions, showing no recurrence nor distant metastases. - MEST (Mixed epithelial and stromal tumor of the kidney)
Mixed epithelial and stromal tumor (MEST) of the kidney is a rare, typically benign lesion that occurs predominantly in perimenopausal women. At computed tomography (CT), it typically manifests as a multiloculated cystic renal mass with a variable proportion of solid and cystic components and containing internal septa that demonstrate heterogeneous and delayed contrast material enhancement. MEST may mimic a variety of benign and malignant renal lesions, such as adult cystic nephroma, complex renal cyst, and cystic renal cell carcinoma. The preoperative diagnosis of MEST can be problematic, and most cases are treated surgically. - By definition, ACN is a multilocular cystic lesion with no solid area at gross examination and with cystic septa less than 5 mm in thickness at microscopy, whereas MEST is a cystic or partially cystic mass with solid areas at gross examination and cystic septa greater than or equal to 5 mm (15). However, it is difficult to differentiate between MEST and ACN on the basis of imaging findings alone. Because both ACN and MEST are benign cystic renal lesions, the precise preoperative radiologic diagnosis may not be critically important, as long as the lesion in question can be differentiated from malignant lesions such as RCC and transitional cell carcinoma.
Mixed Epithelial and Stromal Tumor of theKidney: Radiologic-Pathologic Correlation
Linda C. Chu • Ralph H. Hruban • Karen M. Horton • Elliot K. Fishman
RadioGraphics 2010; 30:1541–1551 - Given its variable appearance, MEST may mimic an array of cystic renal lesions, including adult cystic nephroma (ACN), cystic renal cell carcinoma (RCC), complex cyst, multicystic dysplastic kidney (MDK), an obstructed duplicated renal collecting system, and renal abscess.
Mixed Epithelial and Stromal Tumor of the Kidney: Radiologic-Pathologic Correlation
Linda C. Chu • Ralph H. Hruban • Karen M. Horton • Elliot K. Fishman
RadioGraphics 2010; 30:1541–1551 - “Because most MESTs represent Bosniak category III or IV lesions, a cystic RCC is an important consideration in the differential diagnosis. Cystic change occurs in up to 15% of RCCs. The spectrum of cystic RCC includes multilocular cystic RCC, RCC arising from a preexisting benign cyst, and cystic degeneration of a previously solid RCC. Compared with MEST, cystic RCC tends to have thicker, irregularly enhancing septa and enhancing nodular or solid com-ponents. Complex renal cyst is also part of the spectrum of cystic renal lesions. Complex renal cysts contain thin, nonenhancing internal septa with thin mural calcifications and no mural nodularity.”
Mixed Epithelial and Stromal Tumor of the Kidney: Radiologic-Pathologic Correlation
Linda C. Chu • Ralph H. Hruban • Karen M. Horton • Elliot K. Fishman
RadioGraphics 2010; 30:1541–1551