Etiology of alopecia

I. Nonscarring alopecia
A. Primary cutaneous disorders
1. Androgenetic alopecia
2. Telogen effluvium
3. Alopecia areata
4. Tinea capitis
5. Traumatic alopeciaa

B. Drugs
C. Systemic diseases
1. Lupus erythematosus
2. Secondary syphilis
3. Hypothyroidism
4. Hyperthyroidism
5. Hypopituitarism
6. Deficiencies of protein, iron, biotin, and zinc
II. Scarring alopecia
A. Primary cutaneous disorders
1. Cutaneous lupus (chronic discoid)
2. Lichen planus
3. Folliculitis decalvans
4. Linear scleroderma (morphea)
5. Central centrifugal cicatricial alopecia
B. Systemic diseases
1. Lupus erythematosus
2. Sarcoidosis
3. Cutaneous metastases