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skin corn (clavus)
Skin callus over a bony prominence.
Classification:
1) hard corns:
- generally seen of dorsal aspect of lesser toes & lateral aspect of 5th toe
2) soft corns:
a) found in web space between toes (most commonly 4th web space)
b) pressure point lies between 2 adjacent phalanges
c) maceration of the corn in a web space makes it soft
3) seed corns: (plantar clavi)
- found on plantar surface of the foot
Etiology:
1) improper footwear
2) structural deformities
a) hammer toes with exostosis
b) other bony prominences
Clinical manifestations:
1) corns have more distinct edges & are more rounded than calluses [2]
2) plantar corns are conical-shaped & have a central area extending toward sensitive subcutaneous tissue
3) frequently occur on the sides or tops of toes [2]
4) corns produce pain when foot is placed in a tightly-fitting shoe
5) plantar corns produce pain on weight bearing
Laboratory: none
Differential diagnosis:
1) plantar warts (more vascular than corns)
2) foreign body with secondary keratosis
3) rule out infection & ulcerations in diabetic patients
Management:
1) debridement of excess build-up of epidermis
2) enucleation of apex or central area of corn
3) corn pads to reduce pressure over bony prominences
4) proper footwear
5) liquid nitrogen
6) salicylic acid (non-surgical candidates)
7) referral to podiatrist when conservative measures fail
General
skin callus
References
- Saunders Manual of Medical Practice, Rakel (ed), WB Saunders,
Philadelphia, 1996, pg 970-71
- Medical Knowledge Self Assessment Program (MKSAP) 19
Board Basics. An Enhancement to MKSAP19.
American College of Physicians, Philadelphia 2022