Subungal hyperkeratosis

Excessive buildup of keratin (thickening of the stratum corneum) beneath the nail plate, causing nail thickening, discoloration, elevation, and possible detachment (onycholysis).

Causes

• Infectious causes

  • Onychomycosis (fungal nail infection)

  • Human papillomavirus (HPV) infection

• Dermatologic causes

  • Psoriasis

  • Contact dermatitis

• Repeated nail trauma

• Other causes

  • Nail dystrophies

  • Peripheral vascular disease

  • Aging-related nail changes