Date of Presentation:10/01/2021

Attending pathologist: Anil Parwani, MD, PhD, MBA

Presented by: Bindu Challa, MD

Prepared by: Bindu Challa, MD



A 67 year old female presents with incidental renal mass. Magnetic resonance imaging (MRI) abdomen showed ~3.5 cm partially exophytic complex cystic renal mass in mid to upper pole of left kidney. Surrounding renal parenchyma shows multiple sub-centimeter cysts. Patient was followed up with left partial nephrectomy.


The specimen is designated "left renal mass and perinephric fat" and consists of a 62.9 gm, 5.4 x 3.5 x 3.2 cm portion of kidney. Cut sections of the specimen reveal 2.6 x 2.5 x 2.5 cm multi-loculated cysts with brown liquid contents. The inner lining of each cystic cavity is tan and smooth without any areas of induration or excrescences.

PAX8 was performed and was positive in epithelial lining cells.

What is the most likely diagnosis?

  1. Adult cystic nephroma
  2. Multi-locular cystic renal neoplasm of low malignant potential
  3. Mixed epithelial and stromal tumor
  4. Angiomyolipoma with epithelial cysts
Mixed epithelial and stromal tumor