the thumbprint sign is a finding on a lateral C-spine radiograph that suggests the diagnosis of epiglottitis. The sign is caused by a thickened free edge of the epiglottis, which causes it to appear more radiopaque than normal, resembling the distal thumb.
Thumb’ like epiglottitis. Note the swollen epiglottitis like a thumbprint
" enlarged epiglottis in epiglottitis which, instead of its usual thin fingerlike projection, is stubby, like the thumb "
In an abdominal x-ray, the "thumb print sign" has similar appearance of thumbs protruding into the intestinal lumen, but are in fact caused by thickened edematous mucosal folds. Abdominal thumbprinting a sign of intestinal ischemia.