Hair Loss - Differential Diagnosis Framework
Localized / Focal Hair Loss:
 • Scarring Alopecia:
    - Infectious: Dissecting cellulitis of the scalp, Folliculitis decalvans, Tinea Capitis
    - Skin Disease: Discoid lupus erythematosus, Keratosis follicularis (KFSD), Lichen planopilaris, Frontal fibrosing alopecia, Pseudopelade of Brocq, Alopecia mucinosa, Aplasia Cutis
 • Non-Scarring Alopecia:
    - Hair Shafts Intact or Absent: Alopecia areata (+Nail pitting), Alopecia syphilitica
    - Broken Hair Shafts: Tinea Capitis, Trichotillomania, Pressure-induced (postoperative) alopecia, Traction alopecia
Diffuse Hair Loss:
 • Scarring Alopecia: Lupus erythematosus, Lichen planopilaris
 • Non-Scarring Alopecia: 
    - Pattern: Androgenetic alopecia in men (male pattern hair loss), Female pattern hair loss
    - Anagen Effluvium: Chemotherapy/Cytotoxic Drugs, Loose anagen syndrome
    - Patches: Alopecia totalis, Alopecia universalis
    - Telogen Effluvium
    - Endocrine: Hypothyroidism, Hypopituitarism, Post partum
    - Dietary: Iron deficiency, Zinc deficiency, Copper deficiency, Vitamin A excess, Vitamin D deficiency
    - Drugs: Oral contraceptives, Lithium
    - Stress: Post op, Post infection, Psychologic stress

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