Interesting ImageWell-Differentiated Papillary Mesothelioma of the Tunica Vaginalis Testis Imaging on Tc-99m Heat-Denatured Red Blood Cell ScintigraphyChollet, Yves MD*; Hauser, Philippe MD†; Da Silva, Telma MD§; Meuwly, Jean-Yves MD†; Praz, Valentin MD*; Jichlinski, Patrice MD*; Guillou, Louis MD‡; Delaloye, Angelika Bischof MD§; Wisard, Marc MD*; Prior, John MD, PhD§Author Information From the Departments of *Urology, †Radiology, ‡Pathology, and §Nuclear Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Switzerland. Received for publication April 24, 2007; revision accepted November 27, 2007. Work performed at Centre Hospitalier Universitaire Vaudois and University of Lausanne, Switzerland. Reprints: John O. Prior, MD, PhD, CHUV University Hospital, Rue du Bugon 46, CH-1011 Lausanne, Switzerland. E-mail: [email protected]. Clinical Nuclear Medicine: April 2008 - Volume 33 - Issue 4 - p 282-284 doi: 10.1097/RLU.0b013e3181662b2f Buy Metrics Abstract An 18-year-old man presented with a growing painless left scrotal mass. Sonography showed a hydrocele and a homogeneous, well-encapsulated left extratesticular mass with similar echogenicity as the normal testis, suggestive of a splenogonadal fusion. To substantiate the diagnosis, the patient underwent Tc-99m heat-denatured red blood cell scintigraphy showing normal physiological hyperactivity in the spleen but activity similar to the blood pool projecting on the upper part of the left testis. This made testicular splenic tissue less likely. The patient underwent resection and histopathology revealed a well-differentiated papillary mesothelioma. Inguinal orchidectomy was subsequently performed and the patient was free of recurrence at 18 months. © 2008 Lippincott Williams & Wilkins, Inc.