Onychomycosis Disease

BASICS

DESCRIPTION

Infection of nail by fungi (dermatophytes, Candida, molds).

System(s) affected: Skin/Exocrine
Genetics: N/A
Incidence/Prevalence in USA: 22-130 cases/1000 population
Predominant age: Dermatophytes common in adults; even molds in older adults
Predominant sex: Candidal: adult women

SIGNS AND SYMPTOMS

Dermatophytes: Commonly preceded by dermatophyte infection at another site; 80% involve toenails - especially hallux; simultaneous infection of finger and toe nails is rare. Four clinical forms occur:
- Distal subungual onychomycosis
  - Spreads from hyponychium to nailbed to nail-plate
  - Subungual hyperkeratosis
  - Subungual paronychia
  - Onycholysis
  - Nail dystrophy
  - Discoloration: yellow-brown
  - Bois vermoulu ("worm-eaten wood")
  - Onychomadesis
- Lateral onychomycosis (common)
  - Yellowish discoloration lateral nail groove
  - Onycholysis, proximal or distal
- Proximal onychomycosis (rare)
  - Hands or feet
  - Leukonychia: begins under posterior nail groove, spreading to nail plate and lunula
- White superficial onychomycosis (rare)
  - Hallux preferentially affected
  - Infection of upper part of nail-plate
  - Opaque white spots on nail plate eventually merge to involve entire surface of the nail
Candidal:
- Hands 70% - especially dominant hand
- Middle finger most common
- Pain mild, unless secondarily infected
- Pain increases on prolonged contact with water
- Primarily affects tissue surrounding nail
- Begins with cuticle detachment
- Dark yellowish to blackish-brown zone along lateral border of nail
- Secondary ungual changes - convex, irregular, striated nail-plate with dull rough surface
- Onycholysis, especially on hands
- Distal subungual onychomycosis may occur
- Primary involvement of the nail-plate uncommon (thin, crumbly, opaque, brownish nail-plate deformed by transverse grooves)
- Periungual edema/erythema may occur (club-shaped, bulbous fingertips)
- Superficial white onychomycosis - young children
Molds:
- More common over 60 years old
- More common in nails of hallux
- Resembles distal and lateral onychomycosis

CAUSES

Dermatophytes (invade normal keratin)
- Trichophyton rubrum - most common
- Trichophyton mentagrophytes var. interdigitale - 25% as common as T. rubrum (most common pathogen for white superficial onychomycosis)
- Epidermophyton floccosum, T. violaceum, Microsporum species - less common
Candida
- 70% Candida albicans
- C. parapsilosis, C. tropicalis, C. krusei - less common
Molds (invade altered keratin)
- Scopulariopsis brevicaulis
- Hendersonula toruloidea
- Aspergillus species
- Alternaria tenuis
- Cephalosporium
- Scytalidium hyalinium

RISK FACTORS

Dermatophytes
- Warmth, moisture, hyperhidrosis
- Tight fitting shoes, rubber shoes
- Peripheral vascular disease
- Depressed cell-mediated immunity
- Indirect contamination
Candidal
- Direct contamination - ano-vulvar, perirectal pruritus
- Chemical or mechanical damage to cuticle
- Maceration or occlusion
- Contact with substances containing sugar
- Hyperhidrosis
- Chilblain
- Cold hands (Raynaud's phenomenon)
- Psoriatic onycholysis
- Diabetes mellitus
- Hyperparathyroidism
- Addison's disease
- Malnutrition
- Malabsorption
- Dyscrasias
- Malignancies
- Postoperative conditions
- Altered immune function
Molds
- Soil contamination
- Peripheral vascular disease
- Overlapping toes
- Onychogryphosis (deforming overgrowth of nails resulting in hooked or curved state)

DIAGNOSIS

LABORATORY

KOH preparation: clip or file away some of nail-plate as needed, collect scales from stratum corneum of most proximal area (beneath nail or crumbling nail itself with 1 mm curette), 5% KOH + gentle heat, 100% sensitive if > 2 preps examined
Cultures - negative in 30% (secondary to loss of dermatophyte viability; improved by immediate culture on Sabouraud's and CC media)
Histologic examination of keratin, punch or scalpel biopsy - proximal lesions with PAS stain
All are influenced by quality of sampling
CD4 < 450

Drugs that may alter lab results: Discontinue all topical medication several days before obtaining sample Disorders that may alter lab results: N/A

PATHOLOGICAL FINDINGS

Pathogens within the nail keratin

SPECIAL TESTS

N/A

IMAGING

N/A

DIAGNOSTIC PROCEDURES

N/A

TREATMENT

APPROPRIATE HEALTH CARE

Outpatient - unless secondary cellulitis/osteomyelitis

GENERAL MEASURES

Avoid factors that promote fungal growth (heat, moisture)
Treat underlying disease risk factors
Treat other fungal infections
Treat secondary infections

SURGICAL MEASURES

Nail removal to remove infected keratin
- Mechanical: soften with occlusive dressing, detach from nailbed with tweezers or file with abrasive paper/grinding stone
- Chemical: protect peripheral tissue with adhesive strips, apply ointment of 30% salicylic acid, 40% urea or 50% potassium iodide under occlusive dressing
- Surgical avulsion: for involvement of a few nails

ACTIVITY

Restrictions based on promoting factors, underlying disease or secondary infection

DIET

No special diet

PATIENT EDUCATION

N/A

FOLLOW UP

PREVENTION/AVOIDANCE

Keep affected area clean and dry
Avoid rubber or other occlusive footwear
Avoid tight or ill-fitting footwear
Wear absorbent cotton socks - avoid wool or synthetic fibers
Change clothing and towels frequently and launder in hot water

POSSIBLE COMPLICATIONS

Secondary infections with progression to cellulitis/osteomyelitis

EXPECTED COURSE AND PROGNOSIS

Relapse common; prognosis especially poor if one hand, 2 feet, or multiple nails involved
20–40% of nails fail to respond
40–70% of patients show long-term relapse

MISCELLANEOUS

ASSOCIATED CONDITIONS

Immunodeficiency or chronic metabolic disease

AGE-RELATED FACTORS

Pediatric:

Rare before puberty
Candidal infection presents more commonly as superficial white onychomycosis

Geriatric:

Mold onychomycosis more common
Predisposing diseases more common
Hepatic/renal reserve limited
Decreased ability for topical self-treatment

Others: N/A

PREGNANCY

Drug choices limited

OTHER NOTES

Onycholysis = detachment of nail-plate from nailbed
Dystrophy = thickening, deformation, crumbling
Onychomadesis = shedding of nail
Leukonychia = yellowish-white spots

ABBREVIATIONS

N/A

Clinical Investigations

ROLE OF HOMOEOPATHY

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