Image and content excerpted from the VisualDx clinical decision support system.

Image of Onychomycosis

VisualDx images show variation in age, skin color, and disease stage. VisualDx has 88 images of Onychomycosis.

Full text and additional images for Onychomycosis are available in VisualDx.

Sign up for a Free 30-Day Trial of VisualDx.


B35.1 – Tinea unguium

414941008 – Onychomycosis


Onychomycosis is a fungal infection of the nail caused by dermatophyte fungi (tinea unguium), nondermatophyte molds, or yeasts. Onychomycosis is more frequent in men and is commonly associated with concurrent tinea pedis. It affects toenails more commonly than fingernails, and fingernail infection is typically preceded by or associated with toenail infection. Onychomycosis is classified into 3 patterns relating to the site of invasion of the nail: distal lateral subungual, superficial white, and proximal subungual.

Distal lateral subungual onychomycosis (DLSO) is the most common form of onychomycosis and begins with fungal invasion of the distal nail (hyponychium). In Western countries, DLSO is mainly due to Trichophyton rubrum.

Superficial white onychomycosis (SWO) is due to fungal invasion of the superficial dorsal nail plate, typically caused by T. rubrum in HIV-infected patients and Trichophyton mentagrophytes in immunocompetent individuals.  

Proximal subungual onychomycosis (PSO) is caused by invasion of the proximal nail fold. In the absence of paronychia, PSO is typically due to T. rubrum.

While Candida species are frequently cultured from nails, these species are not thought to be the primary pathogen. Candida is commonly associated with chronic paronychia and occasionally secondarily infects the nail plate. True nail invasion by Candida is seen almost exclusively in chronic mucocutaneous candidiasis.
Immunocompromised Patient Considerations:
SWO and PSO have been reported to be more common in HIV infection and immunocompromised states.

Majocchi-like granulomas, deep ulcerated fungal infections, severe tinea capitis and corporis, and fungal nail involvement are characteristic of an inherited deficiency of CARD9 (caspase recruitment domain-containing protein 9), an inflammatory cascade-associated protein. The disorder is autosomal recessive and is most common in North Africa countries including Algeria, Morocco, and Tunisia. The infections usually begin in childhood and are caused by T. rubrum and Trichophyton violaceum. Lymphadenopathy, high IgE antibody levels, and eosinophilia are common, and the disorder can be fatal.

Try VisualDx FREE for 30 days

VisualDx is your key to a faster, more accurate diagnosis.

Sign up today and receive a FREE 30-day trial to VisualDx.

Your VisualDx subscription includes mobile access via our Apple and Android apps.

VisualDx is a web-based clinical decision support system used in over 1,500 hospitals and large clinics. Learn more.

Get your FREE 30-day trial