Cystic Nephroma/Mixed Epithelial Stromal Tumor

Abstract

Cystic nephroma (CN) is a rare, benign, renal neoplasm composed of epithelial and stromal elements. Only about 200 cases have been reported since 1892 and recurrence has rarely been observed. We report a 32-year-old Hispanic woman, with a history of a right, complex cystic, renal mass treated by robotic decortication 2 years ago, who presented with flank pain, hematuria, and recurrent urinary tract infection. A magnetic resonance imaging study showed a 3.4-cm multicystic lesion with thickened septa and enhancement at the right kidney. The partial nephrectomy specimen revealed a well-circumscribed, multicystic tumor abutting the renal pelvis, with thick septa and smooth walls, filled with clear fluid. Microscopic examination showed variably sized cysts lined by cuboidal epithelium with focal hobnailing, without significant cytologic atypia and mitosis. The epithelial lining was positive for CK19, high molecular weight cytokeratin, and α-methylacyl-CoA racemase suggesting a primitive tubular epithelial phenotype. Primitive glomeruli-like structures were also present. The ovarian-like stroma was condensed around the cysts and was variably cellular with areas of muscle differentiation and thick-walled vessels. The stroma was positive for desmin, estrogen receptor, progesterone receptor, and CD10. We suggest that CN represents a variable mixture of epithelial and stromal elements, immature glomerular, tubular, muscle, and vascular elements, which may be present in variable proportions creating a spectrum of lesions previously described as CN and mixed epithelial and stromal tumors (MEST). This case emphasizes that CN/MEST clinically/radiologically mimics other cystic renal neoplasms, especially cystic renal cell carcinoma and tubulocystic carcinoma, necessitating histopathological examination and immunohistochemial studies for definitive diagnosis. Additionally, CN has the tendency to recur when not completely excised initially.

Benign Lesions Detected in Patients Undergoing Nephrectomy for Renal Mass: Single Center Experiences

“…It is similar to cystic malign pathologies in radiological terms and is reported as case presentations in literature. 23 Oncocytoma was found in 7 (3.4%) patients in our study and it was detected as the most common benign mass following AML concordantly with the literature. Although xanthogranulomatous pyelonephritis which occurs quite rarely due to chronic infection and the resultant renal mass images are benign lesions, they may not always present specific radiological and clinical findings.…”

Mixed Epithelial and Stromal Tumor of the Kidney with Extension into Inferior Vena Cava: Case Report and Discussion of Adult Biphasic Cystic Renal Lesions and the Significance of Vascular Involvement

“…However, the clinical significance of such tumor extension is at present unknown and a longer follow-up may be needed to determine the biology of such tumors. Caution is advised since MEST tumors have been reported to recur locally after incomplete excision [ 38 ] and peritoneal seeding following incomplete resection, resulting in a separate paracolonic MEST, has also been reported [ 39 ].…”

Cystic nephroma: A case report in adult patients

“…[15] Immunohistochemical studies have revealed that stromal contents stain mostly with CD10, calretinin, inhibin, estrogen, and progesteron receptors, while epithelial component has an increased affinity to cytokeratin. [10] The most recent evidence demonstrate that in adult population, tumors with initial diagnosis of CN essentially represent mixed epithelial, and stromal tumors from genetic, and histological perspectives. [17] However some authors think that CN, mixed epithelial, and stromal tumors are different spectrums of the same entity.…”

“…Local recurrence or metastasis is limited to a few cases, and it has been reported that local recurrence especially in patients who underwent partial nephrectomy is a possibility which might be related with incomplete resection. [3,10] Contrarily, Castillo et al [4] presented a series of 29 cases, and couldn't encounter any postoperative local recurrence or metastasis. Also in our case we didn't observe any local recurrence or metastasis.…”