PMC5369390_01
Abdominal MRI. T2 phase coronal section (A) illustrating a cystic structure measuring 6.9 x 6.6 cm in the left retroperitoneum with an area of nodularity medially. Axial sections in the T1 phase before (B) and after (C) gadolinium contrast through the medial nodular structure showing subtle nodular and cystic wall enhancement. Axial section in the T1 phase after contrast illustrating that two cystic structures are associated with the left kidney (D).
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Subsequent MRI (Fig. 1) revealed hemorrhage in some portions of the cysts, as well as cystic wall and nodular enhancement, suggesting a possible malignancy.
Histopathology from surgical specimen. (A) Illustrates normal renal parenchyma (bottom) with adjacent cyst wall (top) separated by fibroconnective tissue (middle). The top of the cyst wall consists of soft intestinal epithelium with an underlying muscular layer. Malignant transformation of the cyst wall into adenocarcinoma (B) is shown with neoplastic glands depicted on the bottom of the image. Transformation of normal intestinal to dysplastic epithelium can be seen in (C).
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Histologically (Fig. 2), the internal mucosa of the cyst showed columnar epithelium with high-grade dysplasia and carcinoma in situ with focal individual cell infiltration into the superficial portion of the inferior part of the cyst.