Proximal subungual onychomycosis
The dermatophyte fungus Trichophyton rubrum is the most common causative agent. Other organisms include Candida, Fusarium, and Aspergillus.
Paronychia may lead to proximal nail plate invasion. Candida and Fusarium are often responsible.
The entire nail may eventually become involved. Toenails are more commonly involved than fingernails. Spread to involve multiple toenails often occurs without treatment. Concomitant nail fold infection (paronychia) may lead to pain and discomfort.
Males are affected more often than females, but there is no ethnic predilection. Adults are affected more often than children.
B35.1 – Tinea unguium
403105006 – Proximal subungual onychomycosis
- Superficial onychomycosis – The fungal infection is on the superficial aspect of the nail plate and can be removed by scraping with a file.
- Distal lateral subungual onychomycosis
- Psoriatic nail changes – Look for pitting, oil spotting, onycholysis.
- Lichen planus nail changes – Look for nail plate atrophy and fissuring of the nail or pterygium.
- Subungual verruca – Look for evidence of a verrucous papule under the nail.
- Nail squamous cell carcinoma – A biopsy may be necessary to rule out this entity.