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Clinical Summary

Onychomycosis is an invasion of the nails by any fungus. Four clinical subtypes are described. Distal subungual presents as discolorations of the free edge of the nail with hyperkeratosis, leading to subungual accumulation of friable keratinaceous debris. White superficial consists of sharply outlined white areas on the nail plate, which leave the surface friable. Proximal subungual presents as discolorations that start proximally at the nail fold. Candidal onychomycosis encompasses the entire nail plate, leaving the surface rough and friable.

Management and Disposition

Oral antifungals are required to eradicate the fungus. Refer to a dermatologist or primary care physician.


  1. All that causes the nail plate to separate from the nail bed is not necessarily fungus. Psoriasis, lichen planus, and various other nail dystrophies, such as distal onycholysis (caused by excessive water exposure or drugs) must be differentiated from this fungal infection.

  2. Treatment requires proper monitoring and long-term follow-up.

FIGURE 13.100

Onychomycosis. Invasion of the nail bed by fungus. (Photo contributor: Lawrence B. Stack, MD.)

FIGURE 13.101

Onychomycosis. Note that multiple nail beds have been invaded by the fungus, leading to chronic hyperkeratosis and subungual accumulation of friable keratinaceous debris. (Photo contributor: Department of Dermatology, Wilford Hall USAF Medical Center and Brooke Army Medical Center, San Antonio, TX.)

FIGURE 13.102

Onychomycosis. Multiple nail beds with dystrophy and yellow subungual debris. (Photo contributor: J. Matthew Hardin, MD.)

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