The cysts are lined by tubular epithelium which may range from low columnar to cuboidal to flattened epithelium. Solid areas and nephroblastomatous elements are absent from cyst walls. The stroma in this image is scant and mostly sclerotic. It may be fibroblastic and may even show smooth muscle, skeletal muscle, or cartilage. Some cases show dense fibroblastic ovarian type stroma in the septa separating cysts. However, ovarian type stroma is seen more commonly in Mixed Epithelial and Stromal Tumor of the kidney which is discussed later.