Acro-osteolysis

Acro-osteolysis refers to resorption of the distal phalanx. The terminal tuft is most commonly affected but the shaft of the distal phalanx can also be affected in a few conditions. It is associated with a heterogeneous group of pathological entities and, some of which can be remembered by using the mnemonic PINCH FO.

Pathology

Multiple digits

Terminal tuft resorption

• scleroderma ⁴
• Raynaud disease
• psoriatic arthritis
• thermal injury 
  • extreme cold: frostbite
  • extreme heat: burns, electricity
• trauma
• hyperparathyroidism
• epidermolysis bullosa
• porphyria
• drugs
  • phenytoin (occurs in infants of epileptic mothers treated with phenytoin) ⁷
  • ergot poisoning/abuse
• insensitivity to pain, e.g. leprosy
• juvenile chronic arthritis
• dermatomyositis
• vascular occlusion ⁵
• reactive arthritis ⁶
• pityriasis rubra pilaris (very rare skin condition) ⁸
• pachydermoperiostosis ⁹

Midshaft resorption

• polyvinyl chloride exposure
• primary acro-osteolysis: Hajdu-Cheney syndrome
• hyperparathyroidism (also causes terminal tuft resorption)

Single digit 

• epidermal inclusion cyst ³
• glomus tumor of digit ³