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What is Malum perforans and explain in detail?
Malum perforans is a long-lasting, usually painless ulcer that penetrates deep into or through the skin, usually on the sole of the foot (in which case it may be called malum perforans pedis). It is often a complication in diabetes mellitus and other conditions affecting the nerves.

Presentation
These ulcers have punched-out edge and slough in floor, resembling gummatous ulcer. Surrounding area might have loss of sensation.

Cause
This condition results from denervation of areas exposed to day-to-day friction of bony prominences. The denervation may be result of any of the following diseases:
Spinal injuries
Leprosy
Peripheral nerve injury
Diabetic neuropathy
Tabes dorsalis
Transverse myelitis
Meningomyelocele
Syringomyelia

Pathophysiology
Normal pressure and pain sensations are essential for protecting the foot from excessive and prolonged pressures over bony prominences