Dermatology Book

http://www.fpnotebook.com/

OnychomycosisAka: Tinea Unguium

Advertisement

  1. Definition
    1. Fungal infection affecting the Toenail or Fingernail
  2. Epidemiology
    1. Infection after age 60 years most common
    2. Rarely occurs in children unless predisposing factors
      1. Immunosuppression (e.g. AIDS)
      2. Extensive fungal skin involvement
      3. Family History of onychomycosis
  3. Etiology
    1. Person to person transmission
  4. Types
    1. Distal Subungual (most common)
      1. Affects distal and lateral Toenails and Fingernails
      2. Associated with Tinea Pedis
      3. Most common etiology: Trichophyton rubrum
    2. White superficial onychomycosis (10% of cases)
      1. Most common etiology: Trichophyton mentagrophytes
      2. May affect entire Toenails
        1. Starts as opaque, well demarcated white spots
        2. Spots coalesce to involve entire nail
    3. Proximal Subungual (least common)
      1. Most common etiology: Trichophyton rubrum
      2. Affects proximal Fingernails and Toenails
      3. Fungi invade proximal nail fold to enter nail
      4. Predisposing factors
        1. Immunocompromised status (e.g. AIDS)
        2. Local trauma
    4. Candida onychomycosis
      1. Associated with Chronic Paronychia (Candida)
    5. Total dystrophic onychomycosis
      1. Total nail plate destruction from above types
  5. Signs: Nail plate changes
    1. Discoloration (white or yellow)
    2. Opacification
    3. Distribution based on type (see above)
  6. Labs
    1. Potassium Hydroxide (KOH): Subungual debris scraping
      1. Test Sensitivity: 80%
      2. Test Specificity: 72%
    2. Nail Biopsy: Periodic acid schiff stain (effective, but expensive and not widely available)
      1. Test Sensitivity: 92%
      2. Test Specificity: 72%
    3. Fungal Culture
      1. Efficacy
        1. Test Sensitivity: 59%
        2. Test Specificity: 82%
      2. Distal subungual onychomycosis
        1. Clip nail short
        2. Apply curette to nail bed near Cuticle for sample
        3. Also scrape underside of nail plate
      3. White superficial onychomycosis
        1. Scrape nail plate surface white area for sample
      4. Proximal superficial onychomycosis
        1. Pare nail plate near lunula
        2. Curette sample from infected nail bed
      5. Candidal onychomycosis
  7. Differential Diagnosis
    1. Only 50% of dystrophic nails are onychomycosis
    2. Candida Paronychia (Chronic Paronychia)
    3. Bacterial Paronychia (Acute Paronychia)
    4. Herpetic Whitlow (Herpes Simplex Virus)
    5. Psoriasis
    6. Lichen Planus
    7. Contact Dermatitis
    8. Local nail trauma
    9. Nail bed tumor
    10. Yellow Nail Syndrome
  8. Management: General Measures
    1. Keep feet dry
      1. Wear cotton socks and change 2-3 times per day
      2. Wear shoes that are breathable
    2. Reduce fungus exposure
      1. Wear foot protection in shared showers (locker room)
      2. Treat Tinea Pedis
    3. Consider nail removal in severe Onycholysis
    4. Optimize chronic disease management
      1. Diabetes Mellitus
      2. Tobacco Cessation
    5. Antifungal Medications
      1. Consider Topical Antifungal as adjunct to those below
      2. Consider longer Antifungal course in some patients
        1. Slow Nail Growth
        2. Extensive nail plate involvement
        3. Diminished blood supply
          1. Peripheral Vascular Disease
          2. Diabetes Mellitus
  9. Management: Antifungal agents
    1. Topical agents are not effective in onychomycosis
      1. Ciclopirox (Penlac)
        1. Requires 48 week application
        2. Marginally better than Placebo
    2. Fluconazole (Diflucan)
      1. See Fluconazole for dosing and monitoring
      2. Cure rates
        1. Mycologic: Nearly 100%
        2. Clinical: 90%
    3. Terbinafine (Lamisil)
      1. See Terbinafine for dosing and monitoring
      2. Cure Rates
        1. Mycologic: 71-82%
        2. Clinical: 60-70%
    4. Itraconazole (Sporanox)
      1. See Itraconazole for dosing and monitoring
      2. Cure rates
        1. Mycologic: 45-70%
        2. Clinical: 35-80%
  10. References
    1. Gilbert (1999) Sanford Guide to Antimicrobials
    2. Andrews (2008) Am Fam Physician 77(10):1415
    3. Crissey (1998) Postgrad Med 103(2):191
    4. Gupta (1997) Dermatol Clin 15(1):121
    5. Harrell (2000) J Am Board Fam Pract 13:268
    6. Rodgers (2001) Am Fam Physician 63(4):663
    7. Scher (1999) J Am Acad Dermatol 40:S21
    8. Weinberg (2003) J Am Acad Dermatol 49:193

Onychomycosis (C0040261)

Definition (MSH)A fungal infection of the nail plate, usually caused by a DERMATOPHYTES; YEASTS; or nondermatophyte MOLDS.
ConceptsDisease or Syndrome (T047)
ICD9110.1, 110.1
MSHD014009
EnglishDermatophytic onychia, Dermatophytosis of nail, Fungal infection of nail, Fungal nail infection, Nail Fungus, OM - Onychomycosis, Onychomycoses, Onychomycosis, Onychomycosis due to dermatophyte, Ringworm of nail, Tinea of nail, Tinea of nail - onychomycosis, Tinea Unguium
Spanishdermatofitosis ungueal, infeccion fungica de la una, infeccion micotica de la una, onicomicosis, onicomicosis debido a dermatofito, onicomicosis por dermatofito, oniquia dermatofitica, tina de las unas, tina de una, tina ungueal, tina ungular
Parent ConceptsDermatophytosis (C0011636), Nail Diseases (C0027339), Tinea (C0040247), Onychomycosis (C0040261), Nail infection NOS (C0343026), Fungal infection by site (C0729543), Ambiguous concept (C1274012)
SourcesCOSTAR, ICD9CM, MSH, MTHICD9, NDFRT, SCTSPA, SNOMEDCT
Derived from the NIH UMLS (Unified Medical Language System)



Navigation Tree