| ALOPECIA
6. CAUSES OF DISCRETE PATCHY ALOPECIA WITH SCARRING
(i) Congenital e.g. aplasia cutis, naevus sebaceus
(ii) Post-trauma e.g. burn, injury, radiotherapy
(iii) Post-infection e.g. kerion, herpes zoster
(iv) Inflammatory dermatosis e.g. DLE, lichen planus, morphoea - common cause of scarring alopecia
(v) Neoplasm e.g. squamous cell carcinoma of skin
(vi) Idiopathic
6.1 Aplasia Cutis
This is a very rare congenital disease and the alopecia is present since birth.
6.2 Naevus Sebaceus
It is a kind of epidermal naevus which presents at birth as a yellowish hairless plaque on the scalp. It becomes more warty after puberty. the diagnosis can be confirmed by skin biopsy. It has potential of undergoing malignant change (e.g. basal cell carcinoma). For this reason, excision of the lesion after puberty is recommended.
6.3 Inflammatory Dermatosis Causing Alopecia
DLE, lichen planus and morphoea are common causes of patchy scarring alopecia. Sometimes, clinically, it is difficult to differentiate them one from another. One should examine the rest of the body to look for any sign that are related to each of these 3 diseases. Of course, skin biopsy of the lesion on scalp is usually helpful.
6.4 Idiopathic Scarring Alopecia (Pseudopelade)
Occasionally, despite thorough examination and investigation, no cause can be attributed to patient's scarring alopecia. If the disease is still active, topical steroid can be tried.
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