Follicular skin diseases
Disorders of hair and scalp key points test
Hair shedding is most often due to:
* Alopecia areata
* Hormonal changes
*! Telogen effluvium
* Iron deficiency
Explanation: Hair shedding is most often due to telogen effluvium and less frequently to anagen effluvium. Iron deficiency and hormonal changes may present with diffuse hair thinning (alopecia).
Telogen effluvium often arises:
* During mid-pregnancy
*! Following severe weight loss
* As a sign of alopecia areata
* As a consequence of harsh shampoos
Explanation: Telogen effluvium may follow pregnancy, weight loss, fever or stress. Harsh shampoos sometimes cause irritant contact dermatitis but this doesn't result in hair loss. Hair breakage can sometimes result from chemical treatment with perming solution and bleach. Severe diffuse alopecia areata may cause anagen effluvium, which may also be caused by several drugs.
Diffuse hair thinning in postmenopausal females is most often due to:
* Androgen-dependent balding
*! Non androgen-dependent female pattern balding
* Systemic lupus erythematosus
Explanation: In postmenopausal females, non-androgen dependent balding may result in diffuse thinning, more pronounced on the vertex. Diffuse hair thinning may also be due to systemic lupus erythematosus, syphilis, iron deficiency, hypothyroidism and alopecia areata. Androgen-dependent hair loss presents as male pattern balding.
Which of the following statements are true about alopecia areata?
*! It is an autoimmune skin disease
* It most often starts after the age of 40
* Total hair loss occurs in about 50% of cases
* There is no effective treatment
Explanation: Alopecia areata is an autoimmune skin disease and most often starts in childhood or young adult life. Alopecia totalis affects 5% and alopecia universalis affects 1% of cases. Although it is not true to say there is no effective treatment, the adverse effects of immune suppressive therapy outweigh their advantages. The strong placebo effect means it is hard to assess the value of more acceptable therapies.
Hair loss is least likely with which of the following conditions affecting the scalp?
* Tinea capitis
* Discoid lupus erythematosus
*! Pityriasis capitis
* Lichen planus
Explanation: Tinea capitis, discoid lupus erythematosus and lichen planus may cause nonscarring or scarring alopecia. Pityriasis capitis (dandruff) is a benign non-inflammatory scaling disorder and does not cause hair loss.
Hirsutism may be induced by:
* Porphyria cutanea tarda
Explanation: Hirsutism may be caused by androgenic drugs such as exogenous testosterone.
Non-hormonal hypertrichosis may be induced by:
#! Porphyria cutanea tarda
Explanation: Hypertrichosis, or non-hormonal excessive hair, may be induced by drugs such as cyclosporin and systemic steroids, or by several skin diseases including porphyria cutanea tarda. Cyclophosphamide results in anagen effluvium and diffuse alopecia.