Disorders of Hair and Nails MCQs

Keratin is a protein produced by skin cells Outermost layer of skin cells contains keratin Hair and nails are also made of keratin Reference: Rooks textbook of dermatology 9th edition, chapter 2, page 2.

Skin Manifestations of Protein Energy Malnutrition (PEM) Crazy pavement 'like skin (parchment) Flag sign' in hair (alternate bands of light and dark colours) Reference: Rooks textbook of dermatology 9 th edition, chapter 63, page 5

The isthmus is the part of hair follicle between the opening of the sebaceous gland and the insertion of arrector pili muscle. Hair follicle stem cells are thought to reside in the bulge area on the isthmus close to the insertion of the arrector muscle. Bulge stem cells are multipotent, migrate in a downward direction, enter the hair bulb matrix and generate the new lower anagen hair follicle. They also migrate distally to form sebaceous glands and to proliferate in response to wounding Reference: Rook's Textbook of Dermatology, 9th Edition, Chapter 2, Page 45

Anagen is the active phase in which the hair follicle grows. Of the total hair on scalp, about 85% are in anagen and this phase can last for several years(average 3 years). The duration of catagen and telogen phase is 3 weeks and 3 years respectively. So the longest phase in anagen. Reference: Rook's Textbook of Dermatology, 9th Edition, Chapter 89, Page 7

In Androgenetic Alopecia, familial tendency is seen and Genetic factors modify the magnitude of the hair follicle response to circulating androgens. Along with genetics, the 5 alpha reductase enzyme plays a central role through the intrafollicular conversion of testosterone to the more active metabolite DHT. DHT binds the androgen receptor with 5 times the avidity of testosterone and is more potent in its ability to cause downstream activation. It leads to Hair follicle miniaturization , which is the histological hallmark of androgenetic alopecia. Converts terminal hair to vellus hair which ultimately shed off. The androgens acts on the androgen receptors, located in the dermal papilla nuclei of the hair bulbs. The dermal papillae are thus, main target of androgens in AGA Reference: Rook's Textbook of Dermatology, 9th Edition, Chapter 89, Page 7

Anagen effluvium is a form of nonscarring alopecia commonly associated with chemotherapy. In this disorder, affected anagen hairs suffer a toxic or inflammatory insult, resulting in fracture of the hair shaft. Shedding usually takes place within 14 days of administration of the offending drug, however, in many instances it is reversible, with hair regrowth occurring upon discontinuation of the offending agent. Reference: Rook's Textbook of Dermatology, 9th Edition, Chapter 89, Page 48

Spontaneous remission occurs in up to 80% of patients with limited patchy hair loss of short duration (less than 1 year) Intralesional steroids are the most effective treatment in patchy alopecia areata. A depot steroid (triamcinolone acetonide 5-10 mg/mL), administered by fine needle injection into the upper subcutis. It will stimulate hair growth at the site of injection in some patients. Multiple injections are usually needed. Reference: Rook's Textbook Of Dermatology, 9 th Edition, Chapter 89, Page 33

An intriguing feature of alopecia areata is the sparing of white hairs. In patients with grey hair, which is an admixture of pigmented and non-pigmented hair, the disease process appears preferentially to affect pigmented hair, so that non-pigmented or white hair is spared. This may result in a dramatic change in hair colour if the alopecia progresses rapidly, and this phenomenon is called as 'going white overnight' syndrome or Canites Subita (Canites = white, subita = sudden). Reference: Rook's Textbook Of Dermatology, 9 th Edition, Chapter 89, Page 31