Skin

Skin

The ageing skin

Skin changes with age are universal, but many changes we associate with ageing are actually due to cumulative sun exposure (photoageing), and could be largely prevented by protecting the skin from the sun (compare an older person’s facial skin to their buttock skin).

Intrinsic ageing does occur, however (Table 23.1), and there are several skin diseases that are age related (eg pruritus, pemphigoid, lichen sclerosus).

Hair changes

50% of the over 50s will have grey hair, as melanocyte numbers drop
Male pattern baldness (affecting the vertex and temples) starts in the late teens and progresses—80% of male pensioners are balding
Women may be affected after the menopause, but it is rarely as severe
Diffuse hair loss occurs in both sexes with advancing age (consider checking for iron deficiency, thyroid dysfunction, renal impairment, hypoproteinaemia, inflammatory skin conditions, use of antimetabolite drugs, etc.)
As hair follicles age, their function may be disrupted, leading to longer, tougher hairs growing in eyebrows, ears, and noses, in both sexes
Postmenopausal hormone changes may cause women to develop hair in the beard area and upper lip

Table 23.1 Age-related changes and their clinical implications

Age-related change	Clinical implications
Epidermis thins, with flattening of the dermo-epidermal junction, limiting transfer of nutrients and making separation of layers easier	Increased tendency to blistering Increased skin tearing
Slower cell turnover	Slower healing of wounds
Less melanocyte activity, with slower DNA repair	Increased photosensitivity, with increased tendency to skin malignancy
Altered epidermal protein binding	Dry, rough, and flaky skin more common Abnormal skin barrier, so more prone to irritant contact dermatitis
Altered connective tissue structure and function	Reduced elasticity and strength of skin
Decreased blood flow through dermal vascular beds	Skin appears cooler and paler Thermoregulation is less efficient Hair and gland growth and function slows
Subcutaneous fat decreases in volume and is distributed differently (eg more abdominal fat)	Thermoregulation is less efficient Protection against pressure injury lessens
Number of cutaneous nerve endings decreases	Cutaneous sensation blunts (eg fine touch, temperature, proprioception) Pain threshold increases
Fewer cutaneous glands	Thermoregulation is less efficient
Nail bed function decreases	Nails become thick, dry, brittle and yellow, with longitudinal ridges
The immune functioning of the skin decreases	Increased propensity to skin infections and malignancies

Photoageing

The dermis thickens with tangled elastic fibres; the epidermis is variable in thickness with regions of both hypertrophy and atrophy—leading to considerable skin changes:

The skin becomes wrinkled (coarse and fine), rough, yellowed, and irregularly pigmented—these changes are all exacerbated by smoking
The skin may develop actinic (solar) elastosis—thickened, yellow skin with rhomboid pattern and senile comedones
Actinic (solar) purpura is a non-palpable rash often on the forearms, due to red cell extravasation from sun-damaged vessels (the platelet count is normal)
Lesions include brown macules, multiple telangiectasia, actinic (solar) keratoses (scaly, rough hyperkeratotic areas on sun-exposed skin), as well as a tendency to skin tumours

Prevention is better than cure for these changes, but topical retinoids may reduce the appearance of wrinkles and pigment, and certain plastic surgery techniques are employed (eg chemical peels and injections of collagen and botulinum toxin).

Sun protection

Avoid unnecessary sun exposure
Stay out of the sun during the hottest time of the day (11am-3pm)
Wear appropriate factor sun screen (increasing sun protection factor for fairer skins)
Areas that are often forgotten include balding heads (wear a hat) and the tops of ears (apply sun screen)

Photosensitizing drugs

Several drugs may interact with ultraviolet (UV) or visible light to cause adverse cutaneous effects. These may be phototoxic or photoallergic reactions. Possible agents include:

Amiodarone
Phenothiazines
Diuretics (including bumetanide and furosemide)
Antibiotics eg tetracyclines (especially doxycycline), isoniazid, ciprofloxacin
Quinine
Procainamide
Hydralazine

Cellulitis

Deep infection of the skin and subcutaneous tissues with oedema, often on the lower leg. More common with increasing age, immunocompromise (eg diabetes) and with a predisposing skin condition (leg ulcer, pressure sore, lymphoedema, toe web intertrigo, traumatic wounds, etc.).

Organisms

Usually Streptococcus (group A, commonly Strep. pyogenes) and/or staphylococcus. With open wounds (eg leg ulcers, pressure sores) and lymphoedema colonization is broader so infecting organisms may be more diverse, including highly resistant bacteria, eg MRSA (see

‘Disease caused by MRSA’, p.612).

Clinical features

Red, hot, tender, raised area with poorly demarcated margins
Portal of entry for bacteria often evident (eg trauma)
Systemic upset may follow (fever, malaise)
May present non-specifically, so always examine the whole skin
Spread can cause lymphangitis with tender nodes in the inguinal region
Risk of bacteraemia (up to 80% in nursing home residents with pressure sores; treat aggressively as mortality is as much as 50%)

Investigations

FBC: elevated white cell count in around 50%
Blood cultures: take in all before antibiotics (positive in 25 %)
Local culture: eg wound swab, injection and aspiration of saline in the dermis, skin biopsy. Rarely needed as empirical treatment often works

Treatment

If the cellulitis is mild, and the patient well, then oral therapy can be used to start. Oral options include phenoxymethylpenicillin + flucloxacillin, erythromycin alone or co-amoxiclav
Draw around the cellulitis with a water-resistant pen to allow accurate subsequent assessments and arrange early review (at 24-48hr)
Elevate the limb: oedema with blistering may cause ulceration
If more extensive, with systemic upset, lymphangitis or worsening on oral therapy, then hospital admission for rest, elevation and parenteral therapy is needed
Options include benzylpenicillin + flucloxacillin or co-amoxiclav for 48hr (or until the erythema starts to recede), then an oral course
Total treatment may be needed for up to 14 days but treat each case individually
If cellulitis complicates ulcers, pressure sores or lymphoedema then broader spectrum antibiotics are needed at outset
Look for and treat toe web intertrigo in all (with topical antifungals)
Cellulitis can be painful: ensure that the patient has adequate analgesia
Older patients will often become dehydrated with bacteraemia: assess clinically (pulse, blood pressure, general condition) and biochemically (urea, creatinine, and electrolytes) giving intravenous fluids in the acute phase if needed

Other bacterial skin infections

Erysipelas

Type of cellulitis that is common in older patients
Strep. pyogenes infection of the dermis and hypodermis
Occurs on face (bridge of nose and across cheeks), and less commonly on legs, arms and trunk
Flu-like prodrome
Well-demarcated edge with erythema, oedema, and pain
Progresses to vesicles that rupture and crust
Portal of entry may be unclear, especially with facial erysipelas
Bacteraemia in 55%; mortality of 10% without treatment
Requires parenteral therapy unless very mild—48hr of iv benzylpenicillin followed by 12 days or oral phenoxymethylpenicillin
Recurs in 30% at some point

Necrotizing fasciitis

Rare and serious infection
Affects soft tissues (usually arm/leg); spreads rapidly along fascial planes
Commonly due to Strep. pyogenes, but polymicrobial infection also occurs (eg Staphylococci, Pseudomonas, Bacteroides, diphtheroids, coliforms)
Patient feels and looks unwell with a high fever
Area of swelling, redness, and tenderness enlarges rapidly and becomes purple and discoloured. Haemorrhagic bullae develop followed by necrosis
Prompt parenteral antibiotics and early surgical debridement essential

▶Key to management is early recognition. Review a patient with cellulitis frequently if they are unwell, looking for rapid spread.

Intertrigo

Common complaint, almost exclusively in older patients, when there is superficial inflammation of skin surfaces that are in contact, eg flexures of limbs, groins, axillae, submammary
Due to friction in a continually warm, moist environment
May be underlying skin disease (eg seborrhoeic dermatitis, seborrhoeic eczema, irritant contact eczema (urine, faeces), psoriasis)
Secondary infection with yeast is common

Fungal skin infections

There are two main groups of fungi that cause infection in humans.

Dermatophytes, eg Tinea species (‘ringworm’)

Infect the feet, groin, body, hands, nails, and scalp
Suspect if there is a distinct edge to an itchy lesion
Confirm diagnosis with skin scrapings, or trial treatment
Topical imidazoles, eg clotrimazole (Canesten® cream) are effective. Terbinafine is more effective, but more expensive
Oral terbinafine will work for more resistant infection but should only be used if topical treatment fails and the diagnosis confirmed

Yeasts, eg Candida albicans (‘thrush’)

Normal commensal of mouth and gastrointestinal tract
Produces infection in certain circumstances, eg moist skin folds, poor hygiene, diabetes, and use of broad-spectrum antibiotics—many of these commonly occurring in older patients
Common sites include genital (associated with catheter use, see ‘Vulval disorders’, p.526), intertrigo (see ‘Intertrigo’, p.590), around the nail (chronic paronychia) and oral thrush (especially if dentures fit poorly, see ‘The elderly mouth’, p.354)
Topical imidazoles, eg clotrimazole are effective for skin infection. Preparations that include hydrocortisone will also reduce inflammation and help to break the itch/scratch cycle
Nystatin, amphotericin, or miconazole lozenges, suspension, or gel can be used for oral infection
More widespread infection (eg oesophageal candidiasis) or those with severe immunodeficiency may require systemic therapy—fluconazole 50-100mg daily is effective

Seborrhoeic dermatitis

Chronic inflammatory condition with erythematous scaly eruptions
Possibly due to a hypersensitivity to Pityrosporum—a yeast skin commensal
Classic distribution—face (eyebrows, eyelids, nasolabial folds, postauricular, beard area), scalp (dandruff), central chest, central back and in older patients only, flexural (axillae, groins, submammary)
May cause otitis externa or blepharitis
Increased prevalence and severity in older patients, exacerbated by poor skin care
Associated with parkinsonism and HIV
Scalp is treated with ketoconazole shampoo
Elsewhere, use ketoconazole shampoo as a wash and apply miconazole combined with 1% hydrocortisone cream
Blepharitis is treated with warm compresses, cleaning eyelids with cotton buds and diluted baby shampoo, and steroid eye cream
Difficult to treat—recurrence is common, and repeated treatments are often required. Aim to control, not cure

Chronic venous insufficiency

Common, ranging from minor cosmetic problems to debilitating leg ulcers.

More common after phlebitis or DVT (25% with a history of DVT will develop venous insufficiency at 20 years, 4% will eventually develop leg ulcers), after leg injury, in obese patients, and with advancing age. Probably more common in women, although female longevity may account for apparent difference.

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