Animal and animal produce inspired signs

Animal and animal produce inspired signs may sound a little silly, but the radiology literature is replete with signs, some more fanciful than others.

Fish and seafood

• fish vertebra (also known as codfish vertebra): biconcave vertebrae as seen in osteoporosis
• fishtail deformity of the elbow: due to abnormal trochlear ossification following a distal humeral fracture in childhood 
• vertebral scalloping: may be anterior or posterior border
• endosteal scalloping: medullary cavity masses, e.g multiple myeloma
• lobster claw sign:  of papillary necrosis
• manta ray sign: of bladder exstrophy 

Poultry and fowl

• eggshell calcification: silicosis and occasionally sarcoidosis
• swan neck deformity: of rheumatoid arthritis
• bird-beak sign: achalasia (also known as rat tail sign)
• beak sign: of arterial dissection 
• beak sign of sigmoid volvulus
• gull wing appearance: erosive osteoarthritis
• hummingbird sign or penguin sign
• the winking owl sign

Domesticated and wild animals

• bull's eye: many of these
• staghorn calculus: struvite renal calculi
• feline oesophagus: horizontal striations seen on barium swallows as a variant of normal.
• eye of tiger sign: classical of Hallervorden-Spatz syndrome
• pleural mouse
• panda sign
  • of the midbrain: Wilson disease
  • of sarcoidosis
• bear's paw sign: xanthogranulomatous pyelonephritis
• scotty dog sign
• hidebound sign: gastrointestinal scleroderma
• dural tail: of meningioma, don't know tail of which animal though
• rat tail sign: achalasia (also known as bird-beak sign)
• rat bite erosions of gout
• bat's wing: pulmonary opacities and 4th ventricle (Joubert anomaly and related syndromes)
• anteater nose sign: calcaneonavicular coalition 
• tigroid pattern or leopard skin sign
• moose head appearance
• snake eyes: appearance of facial canal in the petrous temporal bone

Insects and bugs

• butterfly glioma: nothing "oooh... isn't it pretty" about this one
• butterfly shape of the grey matter of the spinal cord
• butterfly fracture
• butterfly vertebra

Reptiles

• cobra head sign: of ureterocoele

Mythical creatures

• cyclops lesion: usually post ACL repair
• medusa head: of a developmental venous anomaly (DVA) also a sign of severe  portal hypertension

Processed animal product containing foods

• cervical hamburger sign: normal cervical facet joints on axial CT
• honeycomb lung: UIP/pulmonary fibrosis
• mesenteric hamburger sign: mesenteric lymph node enlargement
• omental cake: metastases to omentum 
• sausage digit: underlying inflammatory arthritis or dactylitis
• head cheese sign: hypersensitivity pneumonitis
• leather bottle stomach: of linitis plastica (or water bottle sign)