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Onychomycosis
OVERVIEW: 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 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 DIFFERENTIAL DIAGNOSIS: • Herpetic whitlow
• Eczema
• Pustular psoriasis
• Tumor
• Darier's disease
• Pityriasis rubra pilaris
• Trophic changes, peripheral vascular disease
• Endocrine disease
• Drugs; chemicals
• Trauma
• Alopecia areata
• Lichen planus
• Yellow-nail syndrome (icterus, carotenemia, lymphedema, amyloidosis)
• White acquired nail disease (trauma, acute infection, chronic disease, thallium or arsenic poisoning, hepatic cirrhosis, chronic albuminemia)
• Brown-black pigment (melanotic, hematoma)
• Green dyschromia (Pseudomonas aeruginosa)
• Connective tissue disorders: dermatomyositis, scleroderma, Reiter's
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
MEDICATIONS DRUG(S) OF CHOICE: • Dermatophytes - local: Less effective than systemic, apply under occlusive dressing, may mix with keratinolytic chemicals
• Imidazoles: Clotrimazole (Lotrimin, Mycelex), miconazole (Monistat), butoconazole, tioconazole, econazole (Spectazole), ketoconazole (Nizoral), sulconazole (Exelderm), oxiconazole (Oxistat), terbinafine (Lamisil)
• Unsaturated fatty acid derivatives: Propionic acid, undecylenic acid; haloprogin (Halotex); tolnaftate (Tinactin)
• Amorolfine (Loceryl) 5% topical lacquer
• Dermatophytes - systemic:
• Fluconazole (Diflucan) 400 mg po weekly for 6 months (pulse therapy), overall better tolerated than ketoconazole; expensive; reserve for extreme cases (disseminated disease, immunocompromised)
• Itraconazole (Sporanox): 400 mg po qd for a week per month for 2 months for fingernails and 3-4 months for toenails (pulse therapy)
• Terbinafine (Lamisil) 250 mg po qd for 3 months
• Candida:
• Imidazole derivative
• If bacterial infection present, use antibacterial plus anti-Candidal, e.g., nystatin (Mycostatin), topical amphotericin B (Fungizone), itraconazole (Sporanox) 200 mg po qd for 3 months, or fluconazole 400 mg po weekly for 6 months (pulse therapy)
• Mold:
• 1% iodinated alcohol, Whitfield's ointment, silver nitrate, glutaraldehyde, imidazole derivatives, itraconazole
Contraindications:
• Griseofulvin: porphyria, hepatocellular failure, serious side effects (leukopenia, persistent anemia), pregnancy
• Ketoconazole: hepatocellular disease, pregnancy
• Fluconazole: hepatocellular failure, pregnancy
Precautions:
• Topical agents: use with caution on broken skin, vascular compromise, decreased sensation
• Griseofulvin: monitor for hepatic, renal, hematopoietic side effects; photo-sensitivity; lupus-like symptoms or exacerbation. Take with meals to enhance absorption.
• Ketoconazole: hepatotoxicity (may be severe or fatal), anaphylaxis may (rarely) occur with first dose, decreased testosterone levels
• Fluconazole: decrease dose in renal failure, hepatotoxicity
Significant possible interactions:
• Griseofulvin: warfarin, barbiturates, alcohol, oral contraceptives
• Ketoconazole: warfarin, rifampin, cyclosporine, phenytoin, terfenadine
• Fluconazole: phenytoin (Dilantin), cyclosporine, oral hypoglycemics, oral anticoagulants, rifampin, hydrochlorothiazide
• Itraconazole and ketoconazole require gastric acid for absorption - effectiveness reduced with antacids, H2 blockers, omeprazole, etc.
ALTERNATIVE DRUGS: • Dermatophytes - local: ciclopirox (Loprox, Penlac), naftifine (Naftin), cationic surfactants, e.g., benzalkonium chloride (Cetylcide), cetrimide, cetylpyridinium chloride (Ony-Clear, Fungoid)], halogenated / chlorinated / iodinated derivatives [chloramine, tincture of iodine], dyes [malachite green, crystal violet], mercury derivatives [thimerosal], phenols, glutaraldehyde
• Dermatophytes - systemic: griseofulvin (Fulvicin, Gris-PEG, Grisactin) ultramicrosize, usual adult dose 250-500 mg bid with meals for 6-12 months
FOLLOW UP PATIENT MONITORING: • Topical agents: slow response expected; visits q 6-12 weeks
• Griseofulvin: CBC and liver function tests initially, then q 3 months
• Ketoconazole: liver function tests q 3 weeks for the first 3 months, then monthly
• Itraconazole and fluconazole - liver function tests at start and at 4 weeks
• Terbinafine - liver function and hematologic tests at start and at 4 weeks
• Treatment duration (months): fingernails 6-9s, toenails 9-12, great toenail 12-24
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
SYNONYMS: • Tinea unguium
• Ringworm of the nail
ICD-9-CM: 110.1 Dermatophytosis of nail
112.3 Candidiasis of skin and nails
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