22 Dermatology

The terms atopic eczema and atopic dermatitis are used interchangeably.

See Plate 1.

The natural history tends towards resolution with age. Predicting this is difficult, however, early onset severe disease with associated atopy (hayfever and asthma), and elevated IgE may be associated with a worse prognosis.

See  p.808.

Psoriasis affects 1–2% of the population. One third develops the disease before age 20. It is an immune mediated disorder of T cells. There is a strong genetic component in childhood psoriasis, however, environmental factors such as infection (streptococcal and HIV), stress, smoking (pustular psoriasis) and drugs (beta blockers, calcium channel blockers, thiazides, lithium, interferon and antimalarials) also play a role.

See Plate 2.

Prognosis May be life-long or spontaneously remit.

In children irritant contact dermatitis due to urine, faeces and friction in the napkin area is common. It spares the folds, favours convexities and there may be 2° Candida infection. Frequent nappy changes, drying after bathing and use of a barrier cream may help to prevent this. Hydrocortisone cream in combination with an antifungal cream are the treatment of choice.

Allergic contact dermatitis (delayed type IV hypersensitivity) less common; often occurs in older children. Strong reactions often cause an acute blistering and weeping eczema. Common allergens include nickel (earrings), colophony (sticking plasters), topical medicaments (topical neomycin and preservatives), some henna tattoos, plants (e.g. poison ivy) and rubber. Treatment is allergen withdrawal and topical steroids.

See  pp.196, 841.

Self-limiting condition common between ages 1 and 6yrs.

Probably 2° reaction to viral infections.

Reassurance. Antipruritics may be required.

Resolves after 4–6wks usually, but may persist for several months.

See  p.828.

Acute urticaria affects 10% of the population at some time.

Adverse stimulus → mast cell degranulation → histamine release → localized vasodilatation and ↑ capillary permeability.

Usually idiopathic or triggered by recent viral infection. Other causes include:

Chronic urticaria (defined as acute urticaria not resolving after 2mths) is idiopathic in >90%, but may be caused by:

See Plate 3.

Apart from good history investigation is usually not necessary. Skin prick testing is rarely helpful. If chronic, consider:

Variant of urticaria with significant swelling of subcutaneous tissues, often involves lips, eyelids, genitalia, tongue, or larynx. If severe, may cause acute upper or lower respiratory tract obstruction and may be life-threatening.

As for urticaria. Hereditary angioedema is a rare AD condition caused by active C1-esterase inhibitor deficiency.

As for urticaria. If hereditary angioedema is suspected then measure serum C4 complement level initially.

In severe and recurring cases of hereditary angioedema, tranexamic acid or anabolic steroids (e.g. danazole boosts liver production of C1-esterase inhibitor) are effective, but the latter is rarely used in childhood due to its androgenic effects.

Common pox virus infection affecting infants and young children.

Pink umbilicated (central dimple) papules. Usually affects moist areas, but can occur anywhere. Exacerbated by active eczema or topical steroids.

None if uncomplicated as usually spontaneously resolves within a year. If problematic:

 p.829

See    p.826

Hypersensitivity reaction to insect bites. Itchy small red papules or vesicles evolve into 1–5mm papules +/− surrounding urticaria or surface crusting. Usually on limbs and buttocks. May last for weeks and be exacerbated by new bites elsewhere. Secondary infection common.

Common. Any age. Horny plugging of follicles causes asymptomatic rough papular rash +/− erythema. Affects upper outer arms, front of thighs, cheeks.

Reassurance; emollients, especially urea-based creams.

Reassurance.

Spontaneously resolves after a few weeks.

Immunologically mediated syndrome. May be idiopathic, but usually precipitated by infection (e.g. mycoplasma, herpes simplex, other viruses) or drugs (e.g. sulfonamides, penicillin).

See Plate 4.

If precipitating infection recurs treat early as tends to cause rash again, e.g. topical aciclovir for recurrent HSV.

Complete recovery, but may recur.

Severe, and overlapping condition with erythema multiforme except usually drug induced with viral infection rarely implicated.

See Plate 5.

Prognosis Can be life-threatening. Recovery usually occurs in 3–4wks.

Exotoxin-mediated epidermolysis 2° to Staphylococcus aureus infection (which may be trivial). Occurs in children <5yrs.

Rapid recovery without scarring.

Highly contagious Staphylococcus aureus or β-haemolytic streptococcal superficial skin infection. May be p or complicate other skin disease (e.g. HSV infection, eczema, scabies). Risk factors include overcrowding and poor hygiene.

Skin swabs for bacterial culture and sensitivity.

Rapidly resolves if:

Caused by friction, burns, or insect bites. Sterile aspiration of blister within 12hr after appearance, and pressure dressing may be curative.

See Plate 6 and  p.840

Causes vary with age. Viral causes commonest in younger children. In older children, eczema, psoriasis, and drug reactions (e.g. reaction to ampicillin in glandular fever) predominate.

See  pp.704–709. See Plate 7. Culprits include:

Usually associated with fever and widespread non-specific macular or macular–papular erythematous rash. If child is significantly unwell, lethargic, or peripheral perfusion is reduced, admit and investigate (may be bacterial sepsis). Otherwise, simply reassure and advise symptomatic treatment.

Erythematous macular–papular rash commonest (e.g. to penicillins, cephalosporins, anticonvulsants). Drugs may also cause:

Conditions overlap. Erysipelas is superficial skin infection whereas cellulitis involves deeper subcutaneous tissues. Usually due to Strep. pyogenes or Staph. aureus; occasionally Haemophilus influenzae.

Crops of pink truncal rings (lesions fade rapidly, only to recur) caused by rheumatic fever. No treatment required.

Typically affects older children. Caused by immunological reaction to:

Multiple discrete, large, red, hot, tender nodules on shins (occasionally thigh and forearms) appear over 10 days. Nodules resolve over 3–6wks, with colour changes similar to fading bruises. Fever, malaise, arthralgia, particularly of knees, may also occur.

Investigate for infection. Treat underlying disease; give analgesics.

See also  p.1024. Caused by excessive UV light exposure. Sun avoidance, skin covering, hats, and water-resistant high-factor sunscreens are preventative! Fair-skinned individuals, infants, and those with pre-existing hypopigmented disorders are at particular risk.

Meningococcal disease, as well as other bacterial pathogens, can present with an erythematous rash (see  p.714).

Is the sensation provoking a desire to scratch? If severe, it leads to excoriation, papules or nodules (localized skin thickening), and lichenification.

In absence of obvious underlying skin disease:

In absence of obvious underlying skin disease, investigate as for generalized pruritus.

As for generalized pruritis.

Localized peri-anal itching.

Threadworms may be seen during anal inspection or their eggs seen on microscopy of ‘sellotape’ applied to the anus or skin swab culture.

Localized perivulval itching.

As for pruritus ani.

Generalized pustulosis is unusual. When the child is <2yrs, immunodeficiency, particularly phagocyte dysfunction, should be excluded. Local causes in older children include:

Acne affects 90–100% of teenagers. However, acne may occur in neonates (spontaneous improvement without treatment occurs), infant (often requires treatment and may imply severe acne in later years) and adult (often women older than 25).

Excess sebum production, hyperkeratosis of the hair follicle, Propionibacterium acnes bacterial proliferation and inflammation of the hair follicle lead to acne.

Hyperandrogenism should be suspected if—acne is severe, sudden and of early onset; if there are other signs of hyperandrogenism including irregular periods, hirsuitism, male or female pattern hair loss and deepening of the voice in women; or there is treatment resistance.

Diet has not yet been proven to impact acne, but a healthy diet and exercise are recommended.

Inflammatory (papules, pustules and nodules and cysts) and comedonal (blackheads and whiteheads) acne. There may be hypertrophic and/or atrophic scarring. Acne may affect the face, back, and chest.

Resolves, but may persist for years in some cases. Psychological support is important.

If the patient is well and there is an obvious benign cause, reassure as the rash will resolve spontaneously. If cause unclear, initial investigations should include:

Diffuse soft tissue oedema due to inadequate lymphatic drainage. May be due to developmental defect, e.g. congenital lymphoedema (isolated or part of Turner’s syndrome) or cystic hygroma (which also commonly has a vascular component). Secondary causes include—surgical lymphatic destruction; malignant infiltration; irradiation; recurrent lymphangitis; parasitic infestation (in the tropics—filariasis or elephantiasis).

Is often difficult. Limb elevation, pressure garments, or diuretics may be helpful. Give oral penicillin prophylaxis for increased risk of erysipelas.

Telangiectasias are permanently dilated small vessels. Commonest are spider naevi (dilated capillaries radiating from central arteriole). Less than 5 are considered normal. Laser or cautery of central vessel is rarely required. Five or more telangiectasias may be part of:

Occur on nape of neck, glabella, eyelids and other sites. Often resolve or improve with age (see  p.196).

Naevus flammeus (see Plate 9). A capillary vascular malformation evident at birth, which persists with age. Vivid red or purple macule. May affect any site, but face and neck commonest. Involvement of the eyelid may be associated with glaucoma; segmental ophthalmic branch of trigeminal nerve involvement is associated with a risk of Sturge–Weber syndrome (seizures, hemiplegia, mental retardation). Treatment is pulse dye laser.

A complex venous-lymphatic malformation of the limb associated with limb hypertrophy and varicose veins. Patients may be at increased risk of DVT/pulmonary embolism (PE). Treatment is compression stockings. Lymphatic leakage may be treated with pulse dye laser or CO₂ laser.

Reassurance and monitoring in most cases is all that is required. However, those in critical or cosmeticially sensitive sites may now be treated with oral propranolol by a dermatologist. Pulse dye laser is a useful treatment for ulceration and residual telangiectasia after involution. Surgical correction may be required to remove the fibrofatty residual after involution of large haemangiomas. Segmental, midline and multiple haemangiomas may need further investigation (see  p.824).

Abnormal reaction to cold with localized, inflammatory, red-blue lesions on extremities (e.g. digits, ears). On rewarming there is pain or itching. Lesions may ulcerate. Resolves spontaneously. Prevented by warm clothing and housing!

Episodic artery spasm causes digital ischaemia. The condition is precipitated by cold, finger constriction (e.g. shopping bags), or emotion. Most cases improve with age. Syndrome may be idiopathic (Raynaud’s disease) or 2° (Raynaud’s phenomenon) to:

Fingers ache, burn, or tingle with colour changes of pallor (ischaemia), blue (cyanosis), and red (reactive hyperaemia).

Very common. Caused by infection with human papilloma virus. May affect any age, but mainly school-aged children. Warts exists as painless firm papules with rough hyperkeratotic surface. Capillary ends can usually be seen superficially. Typically affect hands, knees, face, and feet. Usually resolve spontaneously within 3yrs.

Not usually needed. If painful or embarrassing:

See Plate 11 and  p.813.

Most cases due to type I HSV. Type II HSV typically causes genital herpes. Co-infection with active atopic eczema causes eczema herpeticum.

Typically occurs in pre-school children with sore throat, stomatitis, vesicles or ulceration involving mouth, lip, face, and fever. It resolves within 2wks.

Manifests as initial itch or tingling followed by localized vesicles that then break down. Typically lesions are perioral (cold sore). May be idiopathic, but can be precipitated by illness, immunosuppression, menstruation. Early topical aciclovir cream aborts episode or reduces its severity.

This is a very contagious infection due to Herpes zoster. Chickenpox with fever, followed by pruritic vesicular eruption over the trunk spreading to face, mouth, and limbs. Lesions evolve at different rates so that macules, papules, vesicles, and pustules will all be present at once. Secondary bacterial skin infection may occur. Illness may cause life-threatening pneumonitis in congenital infection, older teenagers, or immunosuppressed. Infectivity lasts until FINAL vesicle crusts over.

Can occur in childhood, particularly when varicella occurs <1yr old. May be severe in immunosuppressed. Presents with localized unilateral pain, itching, or hyperaesthesia, followed by vesicular eruption in the distribution of affected dorsal root ganglia. Treat with oral aciclovir if severe and topical antibiotics if 2° bacterial infection.

Infection with coxsackie or enterovirus 71, usually in pre-school children. (Note: Completely different infection from foot and mouth disease in animals!) Painful small vesicles (may be linear or oval) affect mouth (stomatitis), palms, and soles, and occasionally nappy area. Lesions spontaneously resolve within 10 days. If uncertain a viral swab can confirm the diagnosis and also exclude potentially more serious HSV/VZV infection.

Symptomatic.

See  pp.718, 817.

See  p.818.

Annular scaly lesion. Central clearing and sharp edge on trunk, face, or limbs.

Skin scrapings for microscopy and culture.

Topical antifungals, e.g. an imidazole cream, terbinafine cream.

Red, scaling scalp lesions with hair loss and short hair stumps. May present as tender erythematous patch with pustules (kerion). Investigation as for Tinea corporis. Skin lesions appear fluorescent green under Wood’s light.

Skin scrapings and hair pull for microscopy and culture.

Topical antifungal shampoo for one week and 6–8wks oral griseofulvin 20mg/kg/day (plus oral steroids if kerion exists).

Itchy, irritable skin between the toes +/− sole of foot.

Topical antifungal.

Nail infection causes discoloured, friable, and deformed nails.

Microscopy and culture of nail clippings.

Oral antifungal for 3mths (e.g. terbinafine).

include the following:

Skin scrapings for microscopy and culture.

Oral or topical anti-candidal drugs, e.g. nystatin, fluconazole.

infection in post-pubertal children. Asymptomatic hypo/hyper-pigmented macules and scaling on trunk/upper limbs.

Topical imidazole foaming lotion for 3 consecutive nights.

Daily thorough combing with fine-toothed comb combined with single shampoo with lotions of carbaryl (0.5%) or malathion (0.5%).

Many biting insects (e.g. fleas, midges, bedbugs, mosquitoes) may cause erythematous macular lesions with central punctum or papular urticaria.

Infection with Leishmania spp. Endemic in hot climates (e.g. Mediterranean, South America). Spread by sandflies. Large red-brown papule, nodule, ulcer, or granuloma develops on face after several months incubation. Infection usually resolves within 1yr, but leaves a scar.

Intralesional or IV antimony compound if severe.

May be unintentional (e.g. chronic hair twisting due to ponytail or rubbing of occiput in babies) or intentional (trichotillomania) due to hair pulling, twisting, or cutting as part of habit or 2° to anxiety, chronic social deprivation, or psychological disorder. Characteristically, there is an irregular margin, as well as bizarre patterns without complete hair loss, and broken hairs of different length. Hair re-grows once behaviour is modified.

Tinea capitus, ringworm (see  p.828).

Commonest cause is aplasia cutis. Circumscribed areas of the skin are absent, usually on scalp, which presents at birth with raw, red ulcer that heals with scarring and later absent hair growth. There is a significant incidence of other abnormalities (e.g. trisomies). Irreversible absent localized hair growth will also follow other causes of trauma (e.g. burns, skin disease, trauma).

A rare autosomal recessive condition. Hair is present in the newborn period, but total hair loss occurs over the next few months and does not regrow. May be associated with other anomalies.

Hair loss can be 2° to hypothyroidism, diabetes mellitus, severe systemic disease, iron or zinc deficiency, chemotherapy.

Defined as hair growth in areas not normally hairy in either sex.

Localized hypertrichosis may be associated with pigmented naevi, spina bifida occulta, inflammatory skin diseases, or topical steroids.

If required remove or treat underlying cause if possible; hair removal using depilatory creams or waxing.

Male pattern of hair growth in females.

If there is any suggestion that not racial or familial (e.g. virilization evident).

Treat any underlying disease; reassure if racial or familial; hair removal using depilatory creams or waxing.

All diseases are rare and include:

Common, particularly in newborns. It presents as acute inflammation and tenderness of nail folds and surrounding skin.

Topical antiseptics, and, if severe, oral antibiotic, e.g. cephalexin.

Associated with nail dystrophy. It is usually caused by chronic wetness (e.g. thumb sucking, resulting in infection with mixed bacteria and Candida).

Keep nail dry; topical nystatin and antiseptics.

See  p.828.

Common habit. Permanent nail damage may occur if nail matrix damaged.

Gentle dissuasion! Proprietary topical nail solutions that impart a very unpleasant taste may be effective.

Most commonly involves the hallux. A spicule of nail grows into lateral nail fold leading to pain, bacterial paronychia, and granulation tissue.

Caused by trauma leading to haemorrhage under nail. Perforation of nail with hot needle is curative and relieves pain immediately.

Reactions to sunlight can be precipitated by drugs (e.g. thiazide diuretics, nalidixic acid), soaps, perfumes, plant pollens, plant contact (e.g. giant hogweed plant). Most common is a dermatitis-like reaction, but also it may be erythematous or blistering.

Some forms are photosensitive, e.g. erythropoietic protoporphyria (skin burning, redness, swelling, serous crusting +/− subsequent scarring). Treatment is that of the underlying porphyria together with sun protection (see also  p.819).

Red papules and herpetiform vesicles or blisters develop, usually in spring, over light-exposed skin, particularly ear helices. Commoner in boys. Lesions heal without scarring. Topical steroids hasten healing.

Itchy, erythematous, papular rash occurring in sun-exposed areas 6–48hr after exposure. Most commonly affects adolescent girls. Treatment is with high factor sun screen.

An uncommon condition precipitated by sunlight. Irritant papules, exudation, and excoriation develop on both exposed and unexposed skin areas. Treatment is with sun protection. Generally resolves after several years.

A rare autosomal recessive condition in which hypersensitivity to sunlight causes marked erythema followed by dry skin, freckles, hyperpigmentation, atrophy, and scarring. Solar keratosis and skin cancers eventually develop due to the decreased ability to repair DNA damaged by UV radiation.

An autosomal recessive disorder of melanin synthesis. It presents with hypopigmented skin, blonde hair, pink irises, photophobia, reduced visual acuity, nystagmus.

Restrict sunlight exposure, e.g. protective high-level sunscreen; ophthalmology referral.

Comprises a group of several rare genetic (most autosomal dominant) disorders of collagen. In classical EDS the skin is soft, hyperextensible, easily bruised, and heals poorly with thin, atrophic ‘cigarette paper’ scars. Hypermobile EDS is characterized by soft skin with hypermobility of large and small joints. There is no specific treatment.

Result from linear growth exceeding the capacity of new collagen production (e.g. pubertal growth spurt, with glucocorticoids). Linear reddish-purple marks develop. Most commonly occur on lower back and outer thighs. There is no treatment, but the marks slowly fade.

An excessive fibrous tissue response to skin trauma. The cause is unknown, but often familial and more common in Afro-Caribbean children. Skin trauma results in well-demarcated raised, smooth, scar that extends beyond original injury.

Repeated intralesional triamcinolone injections are helpful if given early in keloid development. Radiotherapy also may be helpful if given early or before surgery.

See  p.762. Group of several rare genetic diseases, mostly autosomal recessive, in which there is inadequate or defective collagen production.

Frequent skeletal fractures and multiple deformities; thin skin; defective teeth; hypermobile joints; and blue sclera.

There is no specific treatment. Supportive therapy includes use of wheelchairs, orthoses, and analgesics for fractures, etc. Severe forms are lethal in infancy. Less severe forms lead to short stature, multiple or recurrent fractures, and deformities.

A rare congenital disorder of defective elastin that presents with loose skin folds and easily stretched skin that only slowly returns to original position. It is associated with later hernia, large vessel rupture, and emphysema.

See  pp.784–787, 789. Skin manifestations of connective tissue disorders include the following:

Widespread or ‘butterfly rash’ facial erythema, scalp alopecia, chronic discoid patches, light sensitivity.

Violaceous erythema +/− oedema of face (especially eyelids), upper chest, elbows, knees, knuckles, around nails. Rash may become scaly.

In this idiopathic disorder there is localized sclerosis of the skin. Usually an enlarging large oval plaque of violaceous hue develops which then gradually becomes indurated, smooth, and shiny. Usually resolves spontaneously. Treat severe facial or restrictive linear morphoea with pulsed IV methylprednisolone and oral methotrexate.

This condition manifests as Raynaud’s phenomenon; finger tip ulceration; skin of the face and hands becoming progressively indurated and ‘bound down’ to underlying tissues; restricted facial movements; beaked nose; mouth puckering; skin atrophy; telangiectasia; pigmentation; calcinosis.

Tender nodules (usually lower legs) surrounded by livedo reticularis. Nodules may ulcerate or become necrotic.

In this idiopathic chronic inflammatory skin disorder localized distinct atrophic changes with associated pallor usually affect genital and perianal regions, almost always in females (the male variety is balanitis xerotica obliterans, which causes phimosis). Pruritus, blistering, or erythema may occur. Treat with emollients, or potent topical steroids if severe.

Inherited group of disorders with underlying abnormal keratinization. The most common variants include:

Some types present as a ‘collodion’ baby (LI and CIE most commonly). There may also be eye ectropion and lip eclabium. Otherwise, presents in the first few months of life with dry scaly skin +/− erythema.

Skin biopsy and histology.

Avoid soap and detergents, use bath oils, apply regular urea-containing emollients, or mild keratolytics (e.g. 1% salicylic acid in aqueous cream). If severe, oral retinoids are justified.

Most forms improve with age (except X-linked ichthyosis).

Gluten-free diet; oral dapsone. Prognosis is good.

A group of genetically distinct disorders in which the epidermis separates from dermis. Often presents at birth with sloughing of skin (9 mucous membranes) following minor skin trauma; blister or bulla formation; exhibits positive Nikolsky’s sign. The level of epidermal/dermal cleavage differs between disorders with the more severe form resulting in scarring, finger pseudowebbing, oesophageal strictures, and limb contractions. Nails, hair, teeth may also be affected. Skin biopsy for immunofluorescent mapping determines precise diagnosis.

Supportive (e.g. minimal handling, skilled nursing on silk sheets, foam padding, IV fluid/protein/electrolyte replacement as needed, antibiotics for superficial infection, nutritional support, topical paraffin and non-adherent bandaging of blistering areas). Referral to specialized unit is recommended.

Variable and depends on exact disorder. Generally, autosomal recessive forms are more severe, result in scarring, and present at birth. Severe forms are frequently lethal in newborn period. Prognosis improves with skilled input.

Affects post-pubertal child. Caused by yeast overgrowth, e.g. Malassezia ovale. Presents with erythema with overlying scaling affecting scalp (dandruff), eyebrows, nasolabial folds, cheeks, and joint flexures. Treat with a mild topical steroid/antifungal.

Dietary deficiency (e.g. breastfed very preterm infants) and acrodermatitis enteropathica (rare autosomal recessive defect in zinc absorption).

Infants develop demarcated areas of erythema, scaling, and pustules around the mouth, ears, fingers, and toes, anogenital regions; diarrhoea; FTT.

Low plasma zinc levels.

Oral zinc supplements restore health.

There are many forms, the commonest is hypohidrotic ectodermal dysplasia (X-linked recessive).

Sparse sweat glands, dry skin, sparse hair, thin eyebrows, characteristic facies (prominent frontal ridges in chin, saddle nose, sunken cheeks, thick lips, large ears), and defective peg-shaped teeth. Patients are prone to hyperthermia and heat stroke due to reduced/absent sweating.

Supportive. Avoid hyperthermia and treat appropriately if it occurs with rehydration and salt replacement. Use dental prosthetics.

In this rare X-linked dominant ectodermal dysplasia girls present in the neonatal period with blistering lesions (cropping circumferentially on the trunk and in a linear distribution on the limbs) that within weeks turn into warty plaques and nodules that resolve to leave streaky hyperpigmentation. Ultimately, the lesions regress by late childhood to leave atrophic, streaky areas of hypopigmentation (often most noticeable on the back of the calves). Associated with dental, eye, musculoskeletal, and neurological abnormalities. No specific treatment available.

Caused by self-inflicted skin lesions. Usually affects adolescent girls. Lesions are very variable, but are usually bizarre and sudden in appearance. A helpful clue is that the patient is often inappropriately unconcerned. Occlusive dressing leads to rapid healing. Sympathetic listening is most likely to be helpful. Consider underlying abuse. Psychiatric input may be helpful.

Cause is unknown. Itchy, flat-topped violaceous papules develop, usually over flexor aspects of wrist and trunk. Papules tend to coalesce into hypertrophic plaque. The nails (pits or ridges) and mouth (white lacy network) are also often involved.

Topical steroids. Lesions may recur for several years.

In this developmental, abnormal collection of skin mast cells, single or multiple macular or nodular lesions urticate when rubbed (Darier’s sign). Hyperpigmentation develops after several months. There may be systemic involvement.

Antihistamines. Lesions and pigmentation resolve.