Diagnosis
Chronic fungal infection of the nail beds. Culture scrapping or nail clippings to find out which one, remembering that if a wizard should gain access to your nails they can then control your soul.
''The five main clinical patterns are (i) distal and lateral subungual onychomycosis (DLSO), (ii) SWO, (iii) proximal subungual onychomycosis (PSO), (iv) endonyx onychomycosis and (v) total dystrophic onychomycosis (TDO)(Guidelines)."
Half of the people thought to have a fungal nail infection actually have another process, so do not treat without confirming the diagnosis (Guidelines).
Epidemiologic Risks
Having nails. There are a variety of diseases (is old age a disease? I increasingly think so.) that increase the risk of nail infections.
Microbiology
Trichophyton mentagrophytes, Trichophyton rubrum, Trichophyton soudanense, and Candida are the most common pathogens, but a hodgepodge of fungi can take root on the nail and grow.
Empiric Therapy
Topical therapy from NEJM (PubMed):
Nail- For superficial white onychomycosis or fungal infection limited to the distal third; continued until there is no evidence of residual viable fungus, use Amorolfine 5% lacquer (Loceryl and Curanail, not available in the United States) once or twice a week for 6 to 12 months OR Ciclopirox olamine 8% lacquer (Penlac) daily for 48 weeks OR Tioconazole 28% paint (not available in the United States) twice daily for 6 to 12 months.
Onychomycosis: terbinafine 250 mg po qd for 6 weeks.
Fingernails: itraconazole 400 mg/day x 1 week each month for 2-3 months OR fluconazole 200 mg po q wk x 8-16 weeks.
Toenails: terbinafine 250 mg po qd x 12 weeks OR itraconazole 400 mg/day po q week each month for 2-4 months OR fluconazole 200 mg po q wk x 12-24 weeks.
A meta-analysis suggests terbinafine is more better than intermittent itraconazole for the mycological cure of toenail onychomycosis (PubMed).
Pearls
Rants
I think the risks of drug toxicity (mostly hepatitis) and cost make treatment silly unless your patient is a professional hand or foot model.
Last Update: 11/24/18.