Skin e-book Flashcards

Question

Accessory Structures – Sebaceous Glands

Answer 1

These are absent from the palms of the hands and the soles of the feet. Sebaceous glands secrete sebum, a mixture of triglycerides, cholesterol, proteins and inorganic salts. Sebum coats the surface of the hairs to prevent drying and brittleness. Sebum also has a role in reducing water loss from the skin and inhibition of some bacteria.

Answer 2

Eccrine Glands - These are the most numerous of the sweat glands and are found extensively on the forehead, the palms and the soles of the feet. The secretory portion is located deep in the dermis and the sweat is secreted through the pores on the skin. Their main function is to regulate body temperature and in doing so sweat is formed first on the forehead, moving through the rest of the body before lastly forming on the hands and feet. However, these glands may also be stimulated by emotional stress resulting in “cold sweats”. Apocrine Glands - These are found mainly in the axillae, groin, aureolae and the beard area. Their secretions are more viscous than that of eccrine glands and the secretory portion of the gland is found in the subcutaneous layer opening out onto the hair follicle. The secretion is milky and/or yellowish in colour and its components are metabolised by bacteria on the skin resulting in a characteristic body odour. The apocrine glands do not begin to function until puberty. They are stimulated by emotions and by sexual activity.

Answer 3

Nails are plates of hard, dead, tightly packed keratinized epithelial cells. The nail body is pink due to the capillary blood supply whilst the free edge is white because there is no underlying blood supply. The hyponychium (the nail bed) is a layer of thickened stratum corneum. The nail root is embedded in the nail matrix where mitotic cells produce nail growth (approximately 1mm per week, slightly less in toenails).

Answer 4

* Macule – flat spot up to 1cm in diameter * Papule – raised spot up to 1cm in diameter * Nodule – a solid lesion * Plaque – a raised flat topped lesion * Vesicle – a blister up to 1cm in diameter containing clear fluid * Bulla – a blister greater than 1cm in diameter * Pustule – a pus-containing blister * Crust – dried plasma proteins with or without blood and inflammatory cells * Scale – dry flaky or powdery surface * Purpura – small haemorrhage under the skin or mucous membrane

Answer 5

Dermatitis is characterised by acute inflammatory lesions with either the epidermis or dermis involved, often both. Characteristic patterns of the lesions generally allow identification of the cause. Non-specific dermatitis is known as eczema.

Answer 6

The skin is reddened, itchy and tender. Vesicles form in the epidermis and when these burst clear, yellow fluid is released followed by the formation of a crust. The itchiness may result in repeated trauma from scratching which in turn causes secondary changes to the skin resulting in chronic dermatitis.

Answer 7

This usually begins in infancy and may persist into adulthood. The flexures are most commonly affected and the dermatitis is Type I IgE mediated. There is usually a family history of atopy (including asthma, hayfever and urticaria).

Answer 8

This affects the ankles and lower legs of patients with varicose veins (it is also known as “varicose eczema”). The chronic skin changes are due to inadequate venous drainage.

Answer 9

This occurs following contact with strong agents such as detergents, acids and alkalis. It most commonly affects the hands and is most often due to occupational exposure. It is important to remember that this is not an allergic reaction.

Answer 10

This may have an inherited component and is a Type IV mediated reaction mediated by Langerhans cells. The most common skin allergens are: nickel, rubber, dyes and materials used in cosmetics. The causative allergen is usually identified by contact testing by a dermatology clinic

Answer 11

This is characterised by white or waxy scale. In infants it is largely confined to the scalp and is commonly known as “cradle-cap”. The most common presentation in adults is as dandruff. It is nothing to do with the sebaceous glands!

Answer 12

``` This is a common specific dermatitis. It is often diagnosed by the four Ps: • Pruritic • Purple • Polygonal • Papules ``` It affects the flexor aspects of the forearms, wrists, hands and ankles. It may also affect the trunk and mucous membranes. The dermatitis may persist for years and leaves a patch of pigmented skin when it is resolved.

Answer 13

``` This is a chronic inflammatory dermatitis with a genetic component. It affects the skin of the: • Elbows • Knees • Scalp • Lumbosacral area • Intergluteal cleft • Glans penis Psoriasis is characterised by pink or salmon coloured plaques, often oval in shape, with definite borders. The plaques are covered in a thick white scale. The lesions contain oedematous dermal papillae and if the plaque is lifted pin-prick bleeding results. In 30% of patients there is involvement of the nails also. Psoriasis follows a relapsing/ remitting course where skin turnover is decreased from 35 days to 3-5 days. ```

Answer 14

This presents as red patches with a scaly rim. The primary lesion (the “herald patch”) is quite large, often 2-10 cm in diameter. The secondary lesions are smaller. The scale begins in the centre of the lesion then moves outwards. The cause is unknown but is thought to be viral in origin. It is more common in children and young adults.

Answer 15

Also known as hives or nettle rash this consists of acute, intensely itchy lesions which develop in a matter of minutes. The intense itch comes from degranulation of mast cell releasing inflammatory mediators including histamine. This causes the dermal capillaries to become leaky forming erythmatous vesicles.

Answer 16

Acne is a common problem in the teenage population and can be extremely distressing for the patient. It should, therefore, not be treated lightly. It is thought that acne vulgaris is the result of hyperactivity of sebaceous glands which in turn leads to overproduction of sebum. This then blocks the follicular openings which can result in the formation of blackheads (open comedones), whiteheads (closed comedones), inflammatory papules, nodules and in severe cases cysts. Added to this, the normal skin flora (particularly Propionibacterium acnes) trapped within the follicles can produce proinflammatory mediators which may make the clinical appearance of the lesions worse. Severe acne can lead to scarring, both physical and psychological. In patients with darker skins the scarring may be keloidal in nature.

Answer 17

First line therapies • Antihistamines • Emollients (leave-on and soap substitutes) • Topical corticosteroids

Answer 18

Topical corticosteroids can be very useful in flare-ups of eczema and dermatitis. Hydrocortisone 1% and Clobetasone 0.05% are both available as P medicines for the treatment of mild to moderate episodes of dermatitis with restrictions as to how much and where they can be used. The max length of treatment with non-prescription corticosteroid products is seven days and they should not be used on the face. If longer courses of treatment are required then the patient should see their GP

Answer 19

There are three main categories of treatments: topical, UV light and systemic. Topical treatments include vitamin D analogues (e.g. Calcipotriol), corticosteroids, retinoids (e.g. Tazarotene), Dithranol and coal tar. All of these have been shown to slow down skin cell production and all except Dithranol will reduce inflammation. These drugs can be applied as creams, ointments, gels, lotions or shampoos and again, patient preference often dictates which product is prescribed. UV light therapy usually involves exposure to short wave UV light (UVB). However in more severe cases of psoriasis the patient may be given topical or oral psoralen and exposure to longer wave UV light (UVA) – a therapy known as PUVA. There is an increased risk of skin damage and skin cancer associated with this therapy. Systemic treatments include methotrexate, ciclosporin, anti-TNFs (e.g. etanercept) and monoclonal antibodies (e.g. infliximab, efalizumab).

Answer 20

Oral antihistamines are very effective for the intense itching of urticaria. This is a selflimiting condition and so should not need further treatment.

Answer 21

In mild acne vulgaris topical preparations available over the counter can be of some use. These keratolytic agents are designed to prevent the blockage of follicles (which facilitates the flow of sebum) and they may also have some antibacterial activity. These preparations include Benzoyl Peroxide, Salicyclic Acid, Sulphur and Resorcinol although the latter two are rarely used. Both Benzyol Peroxide and Salicylic Acid are irritant to the skin and should be used at the lowest available concentrations in the first instance. If these are tolerated, then the concentration can be increased. Patients should be counselled that it may take up to 3 months for the benefits to be seen and so perseverance with therapy is important. If these products fail to achieve a desirable result, other topical agents are available on prescription. These include Tetracycline, Clindamycin, Tretinoin and Adapalene. If treatment with first line agents is not successful, second line therapy can be added. This usually consists of low dose oral antibiotics: Oxytetracycline, Tetracycline, Doxycycline, and Lymecycline. Minocycline is as effective as these but carries a greater risk of lupus erythmatosus-like syndrome. In female patients where acne is thought to be hormonally linked, Co-Cyprindiol (Cyproterone Acetate + Ethinylestrodiol) may be of value. If second line agents are ineffective then specialist referral is needed and may result in the prescription of oral Isotretinoin.