TRIPASS XR تري باس

 14

Hair

Hair plays a role in the protective, thermoregulatory and sensory

functions of skin, and also in psychosexual and social interactions.

There are two main types of hair in adults:

• vellus hair, which is short and fine, and covers most of the

body surface

• terminal hair, which is longer and thicker, and is found on

trunk and limbs, as well as scalp, eyebrows, eyelashes,

and pubic, axillary and beard areas.

Abnormalities in hair distribution can occur when there is

transitioning between vellus and terminal hair types (for example,

hirsutism in women) or vice versa (androgenic alopecia). Hairs

undergo regular asynchronous cycles of growth and thus, in

health, mass shedding of hair is unusual. Hair loss can occur as a

result of disorders of hair cycling, conditions resulting in damage

to hair follicles (such as purposeful removal in trichotillomania),

or structural (fragile) hair disorders.

Nails

The nail is a plate of densely packed, hardened, keratinised cells

produced by the nail matrix. It serves to protect the fingertip

and aid grasp and fingertip sensitivity. The white lunula at the

base of the nail is the visible distal aspect of the nail matrix (Fig.

14.2). Fingernail regrowth takes approximately 6 months, and

toenail regrowth 12–18 months.

The history

The possible diagnoses in dermatological conditions are broad

and some diseases have pathognomonic features. Thus, in order

to ensure that your history taking is focused and relevant, it

may be appropriate to ask to glimpse the lesion or rash before

embarking on detailed enquiry.

Common presenting symptoms

These include:

• a rash: scaly, blistering or itchy

• a lump or lesion

• pruritus (itch)

• hair loss or excess hair (hirsutism, hypertrichosis)

• nail changes.

Ask:

• When did the lesion appear or the rash begin?

• Where is the rash/lesion?

• Has the rash spread, or the lesion changed, since its

onset?

• Is the lesion tender or painful? Is the rash itchy? Is the itch

intense enough to cause bleeding by scratching or to

disturb sleep, as in atopic eczema and lichen simplex? Are

there blisters?

• Do the symptoms vary with time? For example, the

pruritus of scabies is usually worse at night, and acne

and atopic eczema may show a premenstrual

exacerbation.

• Were there any preceding symptoms, such as a

sore throat in psoriasis, a severe illness in telogen

effluvium, or a new oral medication in drug

eruptions?

• Are there any aggravating or relieving factors? For

example, exercise or exposure to heat may precipitate

cholinergic urticaria.

• What, if any, has been the effect of topical or oral

medications? Self-medication with oral antihistamines may

ameliorate urticaria, and topical glucocorticoids may help

inflammatory reactions.

• Are there any associated constitutional symptoms,

such as joint pain (psoriasis), muscle pain and

weakness (dermatomyositis), fever, fatigue or

weight loss?

• Very importantly, what is the impact of the rash on the

individual’s quality of life?

Past medical and drug history

Ask about general health and previous medical or skin conditions;

a history of asthma, hay fever or childhood eczema suggests

atopy. Coeliac disease is associated with dermatitis herpetiformis.

Take a full drug history, including any recent oral or topical

prescribed or over-the-counter medication. Enquire about allergies

not just to medicines but also to animals or foods.

Fig. 14.2 Structure of the nail. A Dorsal view. B Cross-section.

Distal edge of nail plate

Nail plate

Lateral nail fold

(paronychium)

Lunula

Cuticle

Eponychium

A

Hyponychium

Nail bed

Nail plate

Distal phalanx

Matrix

Proximal nail fold (paronychium)

Cuticle

B

286 • The skin, hair and nails

Family and social history

Enquire about occupation and hobbies, as exposure to chemicals

may cause contact dermatitis. If a rash consistently improves

when a patient is away from work, the possibility of industrial

dermatitis should be considered. Ask about alcohol consumption

and confirm smoking status.

Document foreign travel and sun exposure if actinic damage,

tropical infections or photosensitive eruptions are being considered.

The risk of squamous cell and basal cell cancers increases

with total lifetime sun exposure, and intense sun exposures

leading to blistering burns are a risk factor for melanoma. The

susceptibility of an individual to sun-induced damage can be

determined by defining their skin type using the Fitzpatrick scale

(Box 14.2).

Ask about a family history of atopy and skin conditions.

The history of a skin disorder alone rarely enables a definite

diagnosis, with perhaps the occasional exception: an itchy eruption

that resembles a nettle rash, the individual components of which

last less than 24 hours, is very likely to be urticaria; and an

intensely itchy eruption that affects all body areas except the

head (in adults) and is worse in bed at night should be considered

to be scabies until proved otherwise.

The physical examination

Proper assessment of the skin involves all the human senses,

with the exception of taste. Once we have listened to the

patient’s history, we look at the rash or lesion, touch the skin,

and occasionally use our sense of smell to diagnose infection

and metabolic disorders such as trimethylaminuria (fish odour

syndrome).

Examination of the skin should be performed under conditions

of privacy in an adequately lit, warm room with, when appropriate,

a chaperone present (p. 20). The patient should ideally be

undressed to their underwear. Routinely, the hair, nails and oral

cavity (p. 187) should be examined, and the regional lymph

nodes (p. 33) palpated. Assess skin type using the Fitzpatrick

scale (Box 14.2).

In documenting the appearance of a lesion or rash, use the

correct descriptive terminology (Box 14.3); doing so often helps

crystallise the diagnostic thought processes.

Distribution of a rash

The distribution of a dermatosis can be very informative. Is the

eruption symmetrical? If so, it is likely to have a constitutional

basis, and if not, it may well have an extrinsic cause. This

golden rule has occasional exceptions (such as lichen simplex)

but holds true in the majority of instances. Its application will

almost always prevent the common misdiagnosis of ‘bilateral

cellulitis’ (bacterial infection) of the legs, which in actuality is

usually lipodermatosclerosis or varicose eczema; bacteria are

not known for their sense of symmetry!

The pattern of a rash may immediately suggest a diagnosis: for

example, the antecubital and popliteal fossae in atopic eczema

(Fig. 14.3A); the extensor limb surfaces, scalp, nails and umbilicus

in psoriasis (Fig. 14.3B); the flexural aspects of the wrists and

the oral mucous membranes in lichen planus; the scalp, alar

grooves and nasolabial folds in seborrhoeic dermatitis; and the

sparing of covered areas in photosensitive eruptions. Does the

rash follow a dermatome (as with shingles), or Langer’s lines of

skin tension (as with pityriasis rosea), or Blaschko (developmental)

lines (as with certain genetic disorders)? The localisation of an

eruption to fresh scars or tattoos may be a manifestation of

sarcoidosis, and the anatomical location may provide a clue to

diagnosis, such as the tendency of erythema nodosum, pretibial

myxoedema and necrobiosis lipoidica (Fig. 14.4) to involve

the shins.

Morphology of a rash

The morphology (shape and pattern) of a rash is equally

important. Violaceous, polygonal, flat-topped papules, topped

by a lacy patterning (Wickham striae), are typical of lichen planus

(Fig. 14.5). The Koebner (isomorphic) phenomenon, where a

dermatosis is induced by superficial epidermal injury, results in

linear configurations (Fig. 14.6A), and occurs par excellence in

14.2 Fitzpatrick scale of skin types

• Type 1: always burns, never tans

• Type 2: usually burns, tans minimally

• Type 3: sometimes burns, usually tans

• Type 4: always tans, occasionally burns

• Type 5: tans easily, rarely burns

• Type 6: never burns, permanent deep pigmentation

Fig. 14.3 Distribution of rash. A Atopic eczema localising to the

flexural aspect of the knees. B Psoriasis involving the extensor aspect of

the elbow.

A

B

The physical examination • 287

14

psoriasis, lichen planus, viral warts and molluscum contagiosum.

Linear or angular markings (erythema or scarring) raise the

likelihood of artefactual (self-inflicted) damage to the skin. The

presence of blisters limits the diagnostic possibilities to a relatively

small number of autoimmune (such as dermatitis herpetiformis,

pemphigoid (Fig. 14.6B) and pemphigus), reactive (including

14.3 Descriptive terminology

Term Definition

Abscess A collection of pus, often associated with signs

and symptoms of inflammation (includes boils and

carbuncles)

Angioedema Deep swelling (oedema) of the dermis and

subcutis

Annular Ring-like

Arcuate Curved

Atrophy Thinning of one or more layers of the skin

Blister A liquid-filled lesion (vesicles and bullae)

Bulla A large blister (>0.5 cm)

Burrow A track left by a burrowing scabies mite

Callus (callosity) A thickened area of skin that is a response to

repeated friction or pressure

Circinate Circular

Comedo A blackhead

Crust (scab) A hard, adherent surface change caused by

leakage and drying of blood, serum or pus

Cyst A fluid-filled papular lesion that fluctuates and

transilluminates

Discoid Disc-like

Ecchymosis

(bruise)

A deep bleed in the skin

Erosion A superficial loss of skin, involving the epidermis;

scarring is not normally a result

Erythema Redness of the skin that blanches on pressure

Erythroderma Any inflammatory skin disease that affects >80%

of the body surface

Exanthem A rash

Excoriation A scratch mark

Fissure A split, usually extending from the skin surface

through the epidermis to the dermis

Freckle An area of hyperpigmentation that increases in the

summer months and decreases during winter

Furuncle A boil

Gyrate Wave-like

Haematoma A swelling caused by a collection of blood

Horn A hyperkeratotic projection from the skin surface

Hyperkeratosis Thickening of the stratum corneum

Ichthyosis Very dry skin

Keratosis A lesion characterised by hyperkeratosis

Lentigo An area of fixed hyperpigmentation

Lichenification Thickening of the epidermis, resulting in

accentuation of skin markings; usually indicative of

a chronic eczematous process

Term Definition

Macule A flat (impalpable) colour change

Milium A keratin cyst

Naevus A localised developmental defect (vascular,

melanocytic, epidermal or connective tissue)

Nodule A large papule (>0.5 cm)

Nummular Coin-shaped

Onycholysis Separation of the nail plate from the nail bed

Papilloma A benign growth projecting from the skin surface

Papule An elevated (palpable) lesion, arbitrarily <0.5 cm

in diameter

Patch A large macule

Pedunculated Having a stalk

Petechiae Pinhead-sized macular purpura

Pigmentation A change in skin colour

Plaque A papule or nodule that in cross-sectional profile is

plateau-shaped

Poikiloderma A combination of atrophy, hyperpigmentation and

telangiectasia

Purpura Non-blanchable redness (also called petechiae)

Pustule A papular lesion containing turbid purulent material

(pus)

Reticulate Net-like

Scale A flake on the skin surface, composed of stratum

corneum cells (corneocytes), shed together rather

than individually

Scar The fibrous tissue resulting from the healing of a

wound, ulcer or certain inflammatory conditions

Serpiginous Snake-like

Stria(e) A stretch mark

Targetoid Target-like

Telangiectasia Dilated blood vessels

Ulcer A deep loss of skin, extending into the dermis or

deeper; usually results in scarring

Umbilication A depression at the centre of a lesion

Verrucous Wart-like

Vesicle A small blister (<0.5 cm)

Wheal A transient (<24 hours), itchy, elevated area of

skin resulting from dermal oedema that

characterises urticaria

Xerosis Mild/moderate dryness of the skin

erythema multiforme, Stevens–Johnson syndrome and toxic

epidermal necrolysis), infective (such as bullous impetigo and

herpes simplex infection) and inherited (for example, epidermolysis

bullosa) disorders. An annular (ring-like) morphology may be seen

in granuloma annulare (Fig. 14.6C), subacute cutaneous lupus

erythematosus, and fungal infections (‘ringworm’).

288 • The skin, hair and nails

extravasation and entrapment in the collagen and elastic fibres

of the dermis.

The tint of the erythema may be helpful: a violaceous hue

distinguishes lichen planus; a beefy-red or salmon-pink colour

often typifies psoriasis; and a heliotrope (pink–purple) colour is

a feature of dermatomyositis, especially on the eyelids.

Macular purpura may be the result of thrombocytopenia or

capillary fragility, but palpable purpura (often painful) usually

indicates vasculitis (Fig. 14.7A) and necessitates exclusion of

vasculitic inflammation in other organs. Purpura elicitable by

pinching the skin (‘pinch purpura’) may be indicative of AL

(light-chain) amyloidosis (Fig. 14.7B).

The vascular contribution to the colour of a rash can be pivotal

in diagnosis since erythematous and purpuric eruptions usually

have very different underlying causes. It is not sufficient to describe

a rash as ‘red’ or ‘pink’; it is essential to demonstrate whether

or not a rash blanches on direct pressure or when the skin

is stretched. Blanchable redness (erythema) indicates that the

red blood cells causing the colour remain within blood vessels;

non-blanchable redness (purpura) is the result of erythrocyte

Fig. 14.4 Necrobiosis lipoidica diabeticorum.

Fig. 14.5 Lichen planus. A Discrete flat-topped papules on the wrist.

B Wickham striae, visible on close inspection. C A white lacy network of

striae on the buccal mucosa.

A

B

C

Fig. 14.6 Rash morphology. A Koebner response. B Pemphigoid.

C Granuloma annulare.

A

B

C

The physical examination • 289

14

There are also a number of subtle clinical signs that can be of

great diagnostic help in common rashes, such as the distinctive

silver-coloured scale that appears when psoriasis is scratched

with a wooden orange stick (Fig. 14.8AB), the urtication that

develops when the pigmented lesions of urticaria pigmentosa

(a form of cutaneous mastocytosis) are rubbed (Darier’s sign),

the separation of epidermis on applying a shearing force in

pemphigus (Nikolsky’s sign), and the very earliest lesions of

lichen planus glinting in reflected light like stars in the night sky

(Fig. 14.8C).

Scratch marks (excoriations) indicate an itchy rash. In any

pruritic eruption it is prudent to look specifically for the burrows

of scabies (Fig. 14.9) on the hands and feet, as well as testing

for dermographism and examining for lymphadenopathy (p. 33),

as urticaria and lymphoma are also important causes of itch.

Fig. 14.7 Purpura. A Cutaneous vasculitis. B AL (light-chain) amyloidosis.

A B

Fig. 14.8 Clinical signs in the diagnosis of skin disease. A Psoriasis

before rubbing the surface. B After surface rubbing. C Lichen planus

showing light reflection from small early lesions.

A B

C

Fig. 14.9 Scabies burrows.

290 • The skin, hair and nails

Fig. 14.10 Lesion morphology. A Malignant

A B melanoma. B Seborrhoeic keratosis.

Fig. 14.11 Basal cell carcinoma. A Viewed with the naked eye. B Dermatoscopy highlights distinctive telangiectasia.

A B

Morphology of lesions

Lesions should be measured and described according to

their anatomical location, colour, symmetry, surface texture,

consistency, demarcation of margin, and whether they are

freely mobile or attached to underlying tissue (p. 32). Remember

to examine the regional lymph nodes. If a pigmented lesion

demonstrates a variable outline and colour variation, the possibility

of malignant melanoma must be considered (Fig. 14.10A). It

is reassuring to see hair growing out of pigmented lesions, as

this usually indicates a benign process such as a melanocytic

naevus. An irregularly roughened, jagged surface texture is

often indicative of sunlight-induced damage (actinic keratosis),

whereas the surface of a seborrhoeic keratosis (Fig. 14.10B) has

a smoother feel. The consistency of a lesion is often of diagnostic

help: for example, the firm, button-like quality of a dermatofibroma

is very characteristic; neurofibromas are rather soft; calcium

deposits are hard; and cysts fluctuate and transilluminate. Basal

cell carcinoma, the most common malignant tumour, is usually

smooth (but may ulcerate); on inspection, it exhibits a milky,

pearlescent colour (which may glint) and irregular telangiectasia

(Fig. 14.11).

Hair and nail signs

General physical examination should always include the hair

and nails. Is there excess hair, either in a masculine distribution

(hirsutism) or not (hypertrichosis), or hair loss (alopecia)? Hirsutism

may be a marker for hyperandrogenism, and hypertrichosis

may be seen in malnutrition states, malignancy and porphyria

cutanea tarda. Discrete, coin-sized areas of hair loss, with small

‘exclamation mark’ hairs at the periphery, are characteristic of

alopecia areata (Fig. 14.12), an autoimmune disorder that may

coexist with other autoimmune disorders. Diffuse, pronounced

hair shedding (telogen effluvium) may be a physiological response

to severe illness, major surgical operations or childbirth, and

may be accompanied by transverse grooves on the finger nails,

which gradually grow out normally (Beau’s lines; see Fig. 3.7B).

Common abnormalities of the nails associated with underlying

disease are covered on page 24 and in Box 3.4 and Fig. 3.7.

The physical examination • 291

14

Fig. 14.12 Alopecia areata.

Fig. 14.13 Nail appearances in systemic diseases. A The typical linear pattern of dermatomyositis with Gottren’s papules on the dorsum of the hand.

B Nail-fold telangiectasia in dermatomyositis, viewed through the dermatoscope. C Yellow nail syndrome in a patient with lymphoedema and pleural

effusions.

A

B

C

Fig. 14.14 Dermatoscope.

Some rare diseases produce specific nail appearances,

such as the ‘ragged cuticles’ and abnormal capillary nail-bed

loops associated with dermatomyositis (Fig. 14.13AB), and the

progressive thickening and opacification of nails in yellow nail

syndrome (Fig. 14.13C).

Supplementary examination techniques

It is often necessary to complement naked-eye observation of the

skin with assisted examination techniques, such as dermatoscopy,

diascopy and Wood’s lamp.

Dermatoscopy

A dermatoscope consists of a powerful light source (polarised or

non-polarised) and a magnifying lens, and enables considerably

more cutaneous anatomical detail to be seen (Fig. 14.14).

292 • The skin, hair and nails

Fig. 14.15 Patch testing.

Dermatoscopy is particularly useful in the assessment of

pigmented lesions but is also often of great help in assessing

other skin tumours, hair disorders and certain infections (scabies,

viral warts and molluscum contagiosum).

Diascopy

The pressure of a glass slide on the skin will compress the

cutaneous blood vessels and blanch the area of contact. If blood

is still visible through the glass, it is because red blood cells have

extravasated (purpura). When granulomatous disorders (such as

sarcoidosis or granuloma annulare) are diascoped, they typically

manifest a green–brown (‘apple jelly’) colour.

Wood’s lamp

Examination of the skin using an ultraviolet light (Wood’s lamp) is

useful in two clinical situations: it enhances the contrast between

normal skin and under- or overpigmented epidermis (making

conditions such as vitiligo and melasma easier to see); and it can

identify certain infections by inducing the causative organisms

to fluoresce (such as erythrasma, pityriasis versicolor and some

ringworm infections).

Investigations

After clinical examination, specific investigative techniques may

be necessary in some cases to enable a precise diagnosis.

Skin biopsy

This involves a sample of skin being removed, under local

anaesthesia, and subjected to histological or immunohistochemical