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Selected Diseases of the ScalpNails

Selected Diseases of the Scalp (continued)

  • Trichotillomania
    • Repetitive pulling, plucking of one's hair
    • Patchy, unnatural pattern, peripheral portions of scalp usually spared
    • < 5% have deep-seated psychological disorders
    • May be life-threatening if there is concomitant trichophagy.  Trichobezoars (clumps of hair) can cause partial obstruction of the intestine.

Tinea capitis
Tinea capitis

  • Tinea capitis
    • In BC, the most common cause of tinea capitis is Microsporum canis, a zoophilic organism found on cats and dogs.  The second most common organism is Trichophyton tonsurans, which is an anthrophilic organism.  M. canis is not contagious from human to human.  T. tonsurans is.
    • Cases may be non-inflammatory or inflammatory.  Inflammatory cases may become secondarily infected with Staph.  Scarring can also occur.

      Diagnosis:  By KOH scraping, mycologic culture, Wood's lamp - only hairs infected by microsporum species fluoresce due to a substance they produce called pteridine.

Telogen effluvium
Telogen effluvium

Telogen effluvium
Telogen effluvium

  • Telogen effluvium
    • Excessive shedding of normal club hairs can be brought about by a number of stresses: parturition, febrile illness, stress, crash diets, drugs (metoprolol, anticoagulants, antithyroid drugs, sodium valproate)
    • Factors cause termination of anagen into catagen and then telogen.  In 2-4 months, the telogen hairs are pushed out.
    • 25,000 hairs must be lost before visible thinning.  Scalp normally has 100,000 hairs. 
    • Normal regrowth in 6 months. 
  • Anagen effluvium
    • Decrease or complete discontinuance of proliferation of matrix cells of the hair shaft
    • Occurs a few days to weeks of the insult
    • Chemotherapy/radiation


Loss of follicular ostia
Loss of follicular ostia

Discoid Lupus Erythematosus
Discoid Lupus Erythematosus


  • Scarring (Cicatricial) alopecia:
    • Far less common than nonscarring alopecias but important to recognize because of potential for irreversible permanent hair loss
    • Loss of follicular ostia
    • Discoid lupus erythematosus (DLE)
    • Lichen planopilaris 
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