Mickey Mouse sign is a medical sign resembling the head of Mickey Mouse, the Walt Disney character. Presented for the very first time at the CHIVA's Meeting, Berlin 2002 by Dr. Lurdes Cerol,^{[citation needed]} this sign has been described as the image at the groin when a dilated accessory saphenous vein (ASV) exists: the common femoral vein (CFV) represents the head of Mickey Mouse while the great saphenous vein (GSV) and the dilated accessory saphenous vein (ASV) represent the ears. The presence of a Mickey Mouse sign has been a great diagnostic clue to check ASV insufficiency.

Some authors, inspired by this sign, described an ecographic "Mickey Mouse View" at the saphenofemoral junction in the groin: the common femoral vein (CFV) represents the head of Mickey Mouse while the great saphenous vein (GSV) and the accessory saphenous vein (ASV) represent the ears.^[1]

But it can be seen in different regions of the body:

• Midbrain of progressive supranuclear palsy (PSP).^[2]
• Polyostotic Paget's disease (Paget's disease affecting multiple bones); a bone scintigraphy with technetium-99m methylene bisphosphonate shows increased uptake at the sites of disease activity. Increased scintigraphic uptake in the body and spine of the vertebrae resembles the head of Mickey Mouse.^[3]
• The portal triad in biliary ultrasound scans, with the portal vein comprising Mickey's head and the common bile duct and hepatic artery his right and left ears, respectively.^[4]
• Pelvic Mickey Mouse sign: bilateral inguinal vesical hernia on transverse axial imaging.^[5]
• Dysmorphic Mickey Mouse RBCs: RBCs with irregular cell walls and migration of hemoglobin into some areas creating the shape of Mickey Mouse ears.^[6] The presence of these dysmorphic cells in urine may indicate intraglomerular haemorrhage.^[7]
• Ureteropelvic junction obstruction (UPJO)^[8]