Published in:
01-08-2017 | Classics in Abdominal Imaging
The “stipple sign”
Published in: Abdominal Radiology | Issue 8/2017
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The “stipple” sign describes the unique appearance of a papillary urothelial neoplasm when contrast material in the urinary tract becomes trapped between the papillary projections. The contrast material creates a pattern of tiny dots when viewed en face (Fig. 1a, b) [1‐3], similar to the pattern produced by the artistic technique of stippling (Fig. 2). This uncommon finding was originally described at excretory urography [1], but the pattern can be translated to CT and MR urography. Though fungus balls, and occasionally blood clots, can trap contrast material within their interstices, the pattern tends to be coarser with blood clots and may assume a lamellar appearance with fungus balls [1].
Fig. 1
A, B Contrast-enhanced axial CT of the pelvis (A) shows an enhancing mass arising from the posterior right bladder wall consistent with a papillary urothelial neoplasm. Coronal reformatted CT image (B) obtained during the excretory phase demonstrates the stipple sign, an appearance created by excreted contrast material interspersed between the papillary projections of the tumor
Fig. 2
Side profile of a young man created using the artistic technique of stippling. Artwork by Virginia Planz, MD
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