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🌱 來自: TABLE 58-4 Causes of Alopecia

Nonscarring alopecia

Telogen Effluvium

• Clinical Characteristics:
  • Diffuse shedding of normal hairs
• Pathogenesis:
  • Follows major stress (high fever, severe infection) or change in hormone levels (postpartum)
  • Stress causes more asynchronous growth cycles of individual hairs to become synchronous, leading to larger numbers of growing (anagen) hairs simultaneously entering the dying (telogen) phase
• Treatment:
  • Observation
  • Discontinue any drugs that have alopecia as a side effect
  • Must exclude underlying metabolic causes (e.g., hypothyroidism, hyperthyroidism)

Androgenetic Alopecia (Male Pattern; Female Pattern)

• Clinical Characteristics:
  • Miniaturization of hairs along the midline of the scalp
  • Recession of the anterior scalp line in men and some women
• Pathogenesis:
  • Increased sensitivity of affected hairs to the effects of androgens-most common cause
  • Increased levels of circulating androgens (ovarian or adrenal source in women)-less common cause
• Treatment:
  • Topical minoxidil
  • Finasteride (oral)
  • Spironolactone (women)
  • Hair transplant
  • Low-dose oral minoxidil

Alopecia Areata

• Clinical Characteristics:
  • Well-circumscribed, circular areas of hair loss, 2-5 cm in diameter
  • In extensive cases, coalescence of lesions and/or involvement of other hair-bearing surfaces of the body
  • Pitting or sandpapered appearance of the nails
• Pathogenesis:
  • The germinative zones of the hair follicles are surrounded by T lymphocytes
  • Occasional associated diseases: hyperthyroidism, hypothyroidism, vitiligo, Down syndrome
• Treatment:
  • Topical anthralin or tazarotene
  • Intralesional glucocorticoids
  • Topical contact sensitizers
  • JAK inhibitors

Tinea Capitis

• Clinical Characteristics:
  • Varies from scaling with minimal hair loss to discrete patches with “black dots” (sites of broken infected hairs) to boggy plaque with pustules (kerion)
• Pathogenesis:
  • Invasion of hairs by dermatophytes, most commonly Trichophyton tonsurans
• Treatment:
  • Oral griseofulvin or terbinafine plus 2.5% selenium sulfide or ketoconazole shampoo
  • Examine family members

Traumatic Alopecia

• Clinical Characteristics:
  • Broken hairs, often of varying lengths
  • Irregular outline in trichotillomania and traction alopecia
  • Fringe sign in traction alopecia
• Pathogenesis:
  • Traction with curlers, rubber bands, tight braiding
  • Exposure to heat or chemicals (e.g., hair straighteners)
  • Mechanical pulling (trichotillomania)
• Treatment:
  • Discontinuation of offending hair style or chemical treatments
  • Diagnosis of trichotillomania may require observation of shaved hairs (for growth) or biopsy, possibly followed by psychotherapy