Fungal nail disease

190 Fungal nail disease



Instruction


Look at this patient’s toenails.



Salient features



History




• Embarrassment from a cosmetic perspective


• Mechanical problems including the fact that nails get snagged in clothing, etc.


• History of diabetes.



Examination




• Nails are white, green or, occasionally, black when the infection is superficial or proximal (Fig. 190.1A,B).


• When the infection is distal there may be onycholysis (Fig. 190.1C,D; see Case 193).


image

Fig. 190.1 Onychomycosis. (A) Proximal subungal onychomycosis. (B) Superficial onychomycosis with a dry, white, powdery surface that can be easily scraped away. (C) Distal onychomycosis: early changes. (D) Distal onychomycosis: late changes where the infection has progressed along a linear channel.


(With permission from Habif 2009.)


Proceed as follows:



• Look at the fingernails: thickened, yellow or white nail with scaling under the elevated distal free edge of the nail plate


• Tell the examiner that you would like to look for underlying immunodeficiency states such as HIV and circulatory disorders (Raynaud syndrome).



Diagnosis


This patient has fungal nail disease (lesion), which is usually caused by Trichophyton or Candida (aetiology), and it is cosmetically unacceptable to the patient (functional status).



Advanced-level questions




What do you understand by the term onychomycosis?


It refers to a fungal infection of nails. Diagnostic criteria (J Am Acad Dermatol 2007;56:939–44) include:



• Clinical primary criteria:


• White/yellow or orange/brown patches or streaks

• Clinical secondary criteria:


• Onycholysis

• Subungual hyperkeratosis/debris

• Nail-plate thickening.

Note: Tinea pedis often occurs concomitantly with pedal onychomycosis, and tinea manuum with infected fingernails.


• Laboratory criteria:


• Positive microscopic evidence

• positive culture of dermatophyte.


What are the different causative organisms?




• Dermatophytes (ringworm, tinea unguium): Trichophyton rubrum, T. interdigitale (toenails are more commonly affected than fingernails). T. rubrum infection is associated with distal or lateral involvement of the nail plate that spreads proximally, eventually affecting the whole nail; this may be associated with proximal subungual nail dystrophy associated with separation of the nail from the bed. T. interdigitale infection, characteristically seen in patients with AIDS, produces superficial white onychomycosis with crumbly white areas on the nail surface.


• Yeasts: Candida albicans, C. parapsilosis (fingernails are more commonly affected than toenails).


• Non-dermatophytes (moulds): Fusarium, Scopulariopsis brevicaulis (toenails are more commonly affected than fingernails).

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Dec 4, 2016 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Fungal nail disease

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