Medullary Sponge Kidney and Paintbrush Appearance

Abstract

The “medullary sponge kidney” or renal tubular ectasia is a degenerative transformation consisting in cystic dilation of collecting ducts in the renal medulla. On tomograms in the excretory phase of enhancement, the delay of contrast agent in widened pyramid tubules is seen forming a “paintbrush appearance” (↑).

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The “medullary sponge kidney” or renal tubular ectasia is a degenerative transformation consisting in cystic dilation of collecting ducts in the renal medulla. On tomograms in the excretory phase of enhancement, the delay of contrast agent in widened pyramid tubules is seen forming a “paintbrush appearance” (↑). This condition can be complicated by medullary nephrocalcinosis, urolithiasis, and abscesses. The changes are most clearly seen with thin collimation of X-rays and multiplanar reconstructions.