C D E F G H I J K L M N O P Q R S T U V W X Y Z blisters easily. In adults, localized blistering of the skin occurs following thermal or chemical burns and sometimes frostbite. Friction due to ill-fitting footwear may cause blistering of the feet, while palmar blisters follow unaccustomed manual toil. Spontaneous blistering always has a pathological cause (Fig. B.13).
Genetic disorders
Rather rarely, a child is born with an inherited defect in the cohesion between the layers of the skin; electron microscopy and genetic studies have now identified Mammography is only indicated in women over the
age of 35, or if pain is non-cyclical and localized to one area of the breast.
BRUISES
Danielle Harari and Mark Kinirons
Subcutaneous bleeding may present as bruises (ecchy-moses), which will vary in colour from dusky red to green, yellow, purple or black depending on the duration of the bruise and the various haemoglobin breakdown products.
Superficial crops of small capillary haemorrhages are called petechiae, and are best seen in the skin, mucous membranes and retina, although they also occur on the internal organs. Ecchymoses result from the confluence of petechiae or from haemorrhages from vessels larger than capillaries. Multiple bruises characterize bleeding disor-ders, whereas petechiae suggest an abnormality of either the platelets or the vessel wall. Multiple skin petechiae and ecchymoses are collectively referred to as purpura.
Bruising frequently occurs after trauma that may be minimal (or unobserved) in elderly persons, and isolated ecchymoses are normal in women and young children.
There are several acquired vascular defects that promote skin bruising. Senile purpura affects older people, usually on sun-exposed areas such as the hands and forearms, and takes several weeks to resolve, leaving brownish discoloration (haemosiderin deposit). Cortico-steroid use causes easy bruising and characteristic purple striae, particularly on the abdomen. Other vascular causes are vasculitis, connective tissue diseases and scurvy (a highly characteristic perifollicular haemor-rhage, although gum bruising is also seen). Painful bruising syndrome occurs in women, and is associated with a tingling sensation followed by bruising over the trunk and limbs, with spontaneous resolution.
BULLAE AND VESICLES (BLISTERS) Barry Monk
A blister is a circumscribed elevation of the skin contain-ing free fluid. Blisters less than 5 mm in diameter are termed vesicles, while larger blisters are termed bullae.
However, blisters of differing sizes may co-exist in some disorders, so the two presentations are best considered together. Blisters can be a feature of a number of impor-tant skin disorders (Box B.7).
Traumatic disorders
Normal skin is a cohesive, multilayered tissue that is remarkably resistant to friction, and only neonatal skin
Traumatic
● Friction, thermal, caustic
● Dermatitis artefacta Genetic
● Epidermolysis bullosa
● Incontinentia pigmenti
● Porphyria cutanea tarda Infective
● Insect bites
● Jellyfish
● Scabies
● Bullous impetigo
● Staphylococcal scalded skin syndrome
● Herpes simplex
● Eczema herpeticum
● Herpes zoster
● Varicella
● Variola
● Hand-foot-and-mouth disease
Inflammatory
● Eczema: contact dermatitis, pompholyx
● Fixed drug eruption
● Erythema multiforme
● Toxic epidermal necrolysis
● Mastocytosis (urticaria pigmentosa)
● Vasculitis Immunobullous
● Pemphigus
● Pemphigoid
● Dermatitis herpetiformis
● Linear IgA disease
● Epidermolysis bullosa acquisita
● Herpes gestationis Box B.7 Bullae and vesicles (blisters)
Figure B.13 Orf.
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infection of the skin with the mite Sarcoptes scabiei, which is passed from person to person by direct physical contact.
The classic lesion of scabies is the burrow; this is an irreg-ular serpiginous track that is most commonly found around the wrists or finger webs, and from which the live mite may be extracted on the end of a needle and demon-strated under the microscope. In babies, blistering on the soles of the feet may be found, and should prompt an examination of other family members (especially the mother).
The sudden onset of a widespread vesicular rash, associated with mild fever and constitutional upset, may suggest chickenpox (varicella; Fig. B.15). Blisters appear in crops, so will be at different stages of evolution, and mucosal blistering may be evident in the mouth. In patients with any form of immunodeficiency or who are receiving immunosuppressive drugs, chickenpox may present with a violent haemorrhagic blistered eruption;
pulmonary involvement may occur, and there is a signifi-cant mortality.
several forms of epidermolysis bullosa. The severest forms may be associated with mucosal (including laryngeal) involvement and severe blistering from birth, whereas other forms are associated with a rather milder degree of blistering, only occurring with friction. Another uncommon but important genetic cause of blistering in infants is incontinentia pigmenti, in which the linear pattern of blistering may lead the unwary to make the incorrect diagnosis of herpes zoster. This is an X-linked disorder, is generally fatal in the affected male, and is associated with a number of ocular and neurological disorders in affected females.
Infectious disorders
A number of infections can cause blistering eruptions in infants and young children. Bullous impetigo (Fig. B.14) is caused predominantly by superficial infection with Staphylococcus. Sometimes the predominant lesion is the honey-coloured oozing crust, but quite marked blistering may occur. The roof of the blisters is fragile and easily ruptured, leading to an appearance that has been likened to a cigarette burn, and that may lead to false accusation of child abuse or neglect. Microbiology swabs will demon-strate the causative organism, and there is a rapid response to topical antibiotics. Some strains of Staphylococcus produce an exotoxin that causes a dramatic superficial exfoliation of the skin resembling that caused by a burn (staphylococcal scalded skin syndrome); this must be distinguished from toxic epidermal necrolysis, a condition that may arise at any age, usually as a result of an idiosyn-cratic reaction to a drug, in which extensive areas of skin apparently dissolve leaving raw weeping areas; the mortal-ity is high.
Another cause of blistering in young children that may cause diagnostic confusion is scabies; this is an
Figure B.14 Impetigo. Figure B.15 Chickenpox in an immunosuppressed patient.
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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z in patients with atopic eczema, who appear to be incapable of mounting an appropriate immune response to the virus, eczema herpeticum (Kaposi’s varicelliform eruption).
Typically, the subject has quite active eczema, and presents with a sudden onset of a diffuse or generalized eruption composed of umbilicated vesicles or crusted erosions. The lesions are often painful, and there may be a severe fever and constitutional disturbance. The condition may be fatal, especially if unrecognized and appropriate treat-ment not instituted.
Herpes zoster (shingles) causes a band of vesicles along a dermatome. It is caused by a secondary activation of varicella virus lying dormant in nervous tissue following primary (chickenpox) infection, sometimes as long as 60 years previously. The condition is uncommon in childhood (except, curiously, in black individuals) and more common with increasing age. It also occurs in those immunosuppressed by drugs or HIV disease, systemic illness or malignancy, where it may be accompanied by toxicity and disseminated chickenpox lesions.
Pain usually precedes obvious skin changes by up to 48 hours. The first sign in the skin is erythema on which grouped clear vesicles appear, which later become umbili-cated and haemorrhagic. Smears from the base of the vesicles show multinucleated giant cells. The limitation to one side of the body, the distribution in one or more dermatomes and the pain usually suffice to distinguish herpes zoster from erythema multiforme and dermatitis herpetiformis (Fig. B.17). When the trunk is affected, the preceding pain may be mistaken for pleurisy or some intra-abdominal condition. The pain may also simulate myocardial infarction, a slipped disc, orchitis or venous thrombosis depending on the site affected. When the second division of the trigeminal nerve is affected, The cropped eruption of chickenpox is one of the
features that may distinguish it from smallpox (variola), in which the lesions erupt together and are thus much more monomorphic. A generalized vesicular or pustular eruption is a rather uncommon sequel to smallpox vaccination.
Perhaps the most common of all infections to cause blistering is herpes simplex (Fig. B.16). The typical lesion of herpetic infection is a cluster of small vesicles, arising on an erythematous background, which crust and heal over a period of 7–10 days, only to recur repeatedly on the same site. When herpetic vesicles occur on mucosal surfaces, the appearance may be somewhat modified; vesicles become macerated and the roofs rub off, leaving painful round erosions or shallow ulcers. The sites most commonly affected are the lips, the face, the buttocks and the genita-lia. Although genital herpes simplex (type II herpes) typically occurs on the genitalia, type I infections may also arise at this site. The first episode of herpes simplex is usually more severe, and is associated with more pain and constitutional upset than subsequent episodes.
Figure B.16 Herpes simplex.
The history of recurrent blistered lesions at the same site is characteristic of herpes, but is also the hallmark of another blistering disorder, fixed drug eruption. In this dramatic and intriguing condition, a blister on an erythematous base recurs in exactly the same location (commonly including the orogenital mucosae) each time affected individuals are exposed to certain medicaments (e.g. phenolphthalein laxatives, codeine, tetracyclines or sulphonamides). The blister resolves, leaving a round patch of post-inflammatory pigmentation, which will then be the site of the next episode. It is remarkable how rarely patients associate the recurrent painful blistering with taking the offending medication.
Herpes simplex, although usually causing a localized
blistering, may be responsible for a widespread eruption Figure B.17 Herpes zoster (shingles).
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have been clearing a patch of overgrown land on a sunny day, and wearing short sleeves or short trousers.
Inflammatory disorders
Another condition characterized by blisters provoked by sun exposure is porphyria cutanea tarda; small vesicles occur on the backs of the hands and are associated with an acquired fragility of the skin. The urine will fluoresce when examined under ultraviolet light. Blistering on the legs may occur in patients with renal failure on haemo-dialysis; its cause is unknown.
Erythema multiforme (Fig. B.20) is an acute eruption that may be triggered by a large number of provoking factors, including viral infections, drugs and radiotherapy.
Recurrent episodes occur if the provoking cause recurs (e.g. herpes simplex infection). The characteristic ‘target’
lesions on the dorsa of the hands and feet, over the knees and elbows, and sometimes more widely, owe their pattern to two erythematous rings of different shade surrounding a central blister. In severe cases, blistering may be exten-sive and associated with fever, prostration and occasion-ally pneumonitis. Involvement of the mucous membranes may be a prominent feature (Stevens–Johnson syndrome;
Fig. B.21).
involvement of the tip of the nose with vesicles indicates infection of the nasociliary branch of the ophthalmic nerve and hence is a sign that keratitis may occur.
Sometimes, the bites and stings of insects cause bullous reactions and present as discrete large blisters on the lower legs, especially in children (Fig. B.18). The sting of jellyfish produces a bullous reaction. In dermatitis artefacta, bullae may be artificially induced by patients themselves (e.g. with caustic chemicals). Blisters can be a feature of acute severe eczema of any cause (Fig. B.19). This is seen on the palms, sides of fingers and soles in pompholyx and in acute contact dermatitis. Some plants, especially of the Umbelliferae family, produce a toxin that is activated by ultraviolet light. Typically, it presents in gardeners who
Figure B.18 Insect bite reaction.
Figure B.19 Phototoxic reaction to a sunscreen cream.
Immunobullous disorders
Three uncommon conditions – pemphigus, pemphigoid and dermatitis herpetiformis – share the features of being chronic blistering eruptions, in which characteristic patterns of deposition of antibodies in the skin can be demonstrated.
Pemphigus comprises a group of disorders, possibly arising in those with a genetic predisposition, in which there is formation of blisters within the epidermis. Both Figure B.20 Bullous erythema multiforme.
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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z by several weeks or months, and at this stage diagnosis is difficult. There is also a circulating autoantibody, but in this case directed at the dermo-epidermal junction. The mucosae can be affected with similar tense bullae, but this is a much less constant feature than in pemphigus.
Cicatricial pemphigoid (benign mucous membrane pemphigoid; Fig. B.23) is a variant in which the blister forms just below the dermo-epidermal junction, so that healing takes place with scarring. Blisters appear on mucosae rather than skin, particularly the eyes, frequently causing blindness.
the skin and mucous membranes are affected. Pemphigus vulgaris begins in the third and fourth decades of life, with equal gender-related incidence. The mucosa of the mouth is often affected before the skin. Fragile intra-epidermal cutaneous blisters occur at any site and quickly become erosions. These are often extensive and slow to heal, and become secondarily infected. The uncomforta-ble oral lesions are the most constant, persisting even when blistering elsewhere is controlled, and making eating difficult. The blistering is thought to be due to a circulating autoantibody directed against the intercellu-lar substance. This is detectable in the blood by an indirect immunofluorescence technique on a suitable substrate tissue (e.g. primate oesophagus), and the titre of this antibody is related to the severity and progress of blister-ing. Fluorescence may also be demonstrated in unfixed skin biopsy specimens. Affected patients also have a higher incidence of organ-specific autoimmune diseases and thymoma. A milder form of pemphigus with positive immunofluorescence may arise in patients under treat-ment with penicillamine.
Chronic familial benign pemphigus (Hailey–Hailey disease) is unrelated, but has histological similarities.
Affected family members show a vulnerability of flexural skin to friction, producing characteristic fissured erosions on the sides of neck, axillae, perineum and oral and vulval lips. Circulating autoantibodies have not been detected.
Bullous pemphigoid (Fig. B.22) is usually a disease of the elderly. Bullae of 2–5 cm diameter arise on an erythema-tous, urticated background on the limbs and trunk. The blisters are thick-roofed and can last for many days; initially, their constituent fluid is clear, but it soon becomes cloudy or haemorrhagic. Once the multiple large blisters occur, the diagnosis can be easily made. However, widespread pruritus, erythema and urticaria may precede the blistering
Figure B.21 Stevens–Johnson syndrome. Figure B.22 Bullous pemphigoid.
Figure B.23 Cicatricial pemphigoid.
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