(1)
Royal Free NHS Foundation Trust, London, UK
Description of skin lesions
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Macule: flat circumscribed lesion <1 cm in diameter, not palpable and characterized by change in colour of skin; macules can be erythematous, hypopigmented, depigmented, hyperpigmented or any other colour (eg black-purple, yellow)
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Patch: flat circumscribed lesion >1 cm in diameter
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Papule: raised solid lesion <1 cm in diameter
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Nodule: raised solid lesion >1 cm in diameter; greatest mass below skin surface
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Plaque: a flat-topped nodule >1 cm in diameter
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Vesicle: clear fluid-filled lesion <1 cm in diameter
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Pustule: pus or exudate-filled lesion <1 cm in diameter
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Bulla: clear fluid-filled lesion >1 cm in diameter
Secondary changes in skin lesions
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Exudate: moist serum, blood or pus from an erosion, bulla or pustule
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Lichenification: grouped flat-topped papules associated with exaggerated skin markings, diffuse thickening and hyperpigmentation
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Excoriations: linear erosions caused by loss of epidermis and superficial dermis due to scratching
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Erosions: loss of superficial epidermis causing superficial depression
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Fissures: linear wedge shaped cracks in the epidermis extending down to the dermis and narrowing at the base
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Ulceration: full thickness loss of epidermis, some dermis and subcutaneous fat
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Scaling: dry flaky surface with normal or abnormal keratin from shed epidermal cells
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Crusting: dried exudates (serum, blood, pus, damaged epithelial cells)
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Scarring: atrophic (thinning or loss of epidemis and/or dermis); hypertrophic
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Maceration: appearance of surface softening due to constant moistness
Distribution of lesions
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Linear
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Grouped
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Circinate
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Annular
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Reticulate
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Serpiginous
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Geographical
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Segmental
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Zosteriform or dermatomal
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Symmetrical
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Peripheral or central
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Limbs (extensor; flexural)
Skin rash assessment
includes:
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Evaluation of general skin appearance: colour; texture; dryness; hydration; odour
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Site predilection: sun-exposed; acral; flexures; extensor surfaces
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If generalized, whether symmetrical (if so, whether central or peripheral) or not
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Shape of skin lesions: round, oval, annular, iris shaped, umbilicated
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Arrangement: isolated, grouped (linear, annular, serpiginous)
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Involvement of scalp, palms, soles, ears, sub-mammary and interdigital areas, hair-bearing areas (axillae, groins); perianal skin
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Involvement of skin appendages: hair; nails
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Mucosal involvement: oral cavity; lips; conjunctivae; nasal cavity
Causes of colouring in macules
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Red: hyperaemia; telangiectasia; petechiae; purpura; ecchymosis
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Blue: haematoma; dermal melanin; cyanosis
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Brown: dermal and epidermal melanin; haemosiderin
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Yellow: carotenoids; bile
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Grey-black: epidermal melanin; foreign bodies; heavy metals; tar
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White: depigmentation (loss of melanin)
Causes of fever and skin rash
Solid rash
Diffuse erythema
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Scarlet fever: sudden onset of sore throat, headache, high fever and chills, malaise, anorexia and nausea followed 1–2 days later by a generalised erythematous pinhead rash, initially on the neck, chest, axillae and abdomen, with sand-paper like texture (due to tiny papules) and sparing of the palms and soles; flushed cheeks with circumoral pallor and strawberry tongue (glossitis, with dilated papillae); pharyngeal exudate, punctate petechiae of the palate and uvula, cervical lymphadenopathy; streaks of petechiae along the axillary skin folds (Pastia lines)
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Drug eruption: morbilliform skin rash, eosinophilia, and systemic symptoms including high fever and organ involvement (DRESS refers to a drug reaction with eosinophilia and systemic symptoms, associated with a triad of fever, skin rash and internal organ involvement, including hepatitis, nephritis, pneumonitis, myocarditis, thyroiditis; there is a two to three-week period between initial exposure to the drug and onset of the reaction)
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Toxic shock syndrome
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Staphylococcal scalded skin syndrome (prodrome of fever, malaise and sore throat; skin tenderness and erythema, initially peri-orificial in the face, and in the neck, axillae and groins, with rapid progression over 24–48 h to diffuse erythroderma, accentuated in flexural areas; peri-oral erythema; large flaccid bullae may develop in the flexures and around orifices; diffuse desquamation leads to peri-oral, peri-nasal and peri-ocular crusting; resolution without scarring takes place within 2 weeks); early toxic epidermal necrolysis
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Erythroderma (red and scaly) secondary to drugs, eczema, psoriasis or T –cell lymphoma; may be idiopathic
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Scombrotoxicity
Petechial-purpuric rash
Palpable purpura
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Meningococcaemia (onset with prodrome of fever, headache and upper respiratory symptoms; a maculopapular rash may precede petechiae; the non-blanching petechial or purpuric rash may initially be found only in warm areas, such as groins and axillae; in patients with darker skin, the soles of the feet and palms of the hands should be examined; the petechiae may have angular edges and a greyish interior; acrocyanosis of the ears, nose, lips, legs and genitalia; cold hands and feet; leg pain; confluent ecchmyoses with central necrosis can progress to gangrene)
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Gonococcaemia: haemorrhagic papules and pustules that develop a crust and become necrotic
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Henoch Schonlein purpura
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Staphylococcal endocarditis
Not palpable
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Idiopathic thrombocytopenic purpura
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Overwheming pneumococcal sepsis (in asplenic individuals)
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Disseminated intravascular coagulation (purpurafulminans)
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Leptospirosis
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Enteroviral infection
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Viral haemorrhagic fevers (Ebola, Marburg)
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Yellow fever; dengue fever
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Toxic shock syndrome
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Rat bite fevers: spirillum minus; streptobacillusmoniliformis
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Capnophagacanimorsus (DF-2) infection: in asplenic individuals, especially after dog bites
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Vitamin C deficiency (scurvy) (peri-follicular purpura; lower limb eccymoses; haemorrhagic gingivitis)
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Catastrophic anti-phospholipid antibody syndrome
Maculopapular rash
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Viral infections: rubella (mild prodrome; pink macular rash appearing on the face and spreading to the trunk and limbs,becoming confluent; red macules or petechiae on soft palate; post-auricular, posterior cervical and suboccipital lymphadenopathy); measles (prodromal 3 Cs of cough, coryza and conjunctivitis with photophobia; generalised erythematous maculopapular rash, starting on the backs of the ears and spreading to the head and neck and rest of the body, turning brown before disappearance; Koplik spots (1 mm white spots, resembling grains of sand, on an erythematous background, in the buccal mucosa in the lower premolar region)); enteroviruses; acute HIV infection; uncomplicated dengue; aminopenicillin therapy in the presence of Epstein-Barr virus
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Rickettsial infections
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Mycoplasma and chlamydial infections
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Bacterial/spirochaetal infections: secondary syphilis; leptospirosis; meningococcaemia
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Acute retroviral syndrome (HIV)
Nodular lesions
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Erythema nodosum
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Streptococcal infections
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Sarcoidosis
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Inflammatory bowel disease
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Disseminated fungal infection
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Disseminated tuberculosis/atypical mycobacteria
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Sweet’s syndrome
Other
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Pseudomonas aeruginosa-echythmagangrenosum
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Lyme disease
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Typhoid
Fluid-filled
Vesiculo-bullous disorders
Diffuse
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Varicella (successive crops of erythematous macules, papules, clear vesicles placed eccentrically on an erythematous base-dew drop on rose petal appearance, pustules, followed by central umbilication, erosion and crusting evolving over 12–24 h; lesions are seen in different stages of evolution; usually no prodrome in children, or a prodrome of nausea, anorexia, myalgia and headache in adults; starts on trunk-centripetal distribution-and spreads to face and limbs-centrifugal spread, sparing palms and soles; reinfection or a second clinical attack virtually unheard of)
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Toxic epidermal necrolysis
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Pemphigus vulgaris
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Erythema multiforme major (Stevens-Johnson syndrome: fever, sore throat, flaccid bullae, painful ulcers in the mouth, lips, anal and genital regions, and keratoconjunctivitis)
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Bullous pemphigoid
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Drug eruptions
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Disseminated herpes simplex (eczema herpeticum: in patients with atopic dermatitis and other widespread skin diseases, resulting from auto-inoculation usually from labial HSV or hetero-inoculation from an infected contact; rapidly spreading blistering eruption evolving into large erosions and ulcers, associated with fever)
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Bullous erythema multiforme
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Staphylococcal infections
Peripheral
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Zoster (unilateral painful eruption of grouped vesicles along a dermatome, with hyperaesthesia and occasionally regional lymph node enlargement)
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Hand-foot-and mouth disease
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Contact dermatitis
Pustular disorders
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Bacterial folliculitis
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Generalisedpustular psoriasis: small, sterile pruritic non-follicular pustules within large areas of erythema; oedema of the hands and feet (de novo or complicating atypical, acral or flexural disease)
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Acute generalized erythematous pustulosis
Risk factors for folliculitis
Staphylococcal
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Shaving, plucking or waxing hair
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Occlusion or maceration of skin
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Topical steroid therapy
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Atopic dermatitis
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Diabetes mellitus
Pseudomonal
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Inadequately chlorinated hot tubs, whirlpools and swimming pools
Lynch PJ, Edminster SC. Dermatology for the non-dermatologist: a problem-oriented system. Ann Emerg Med. 1984;13: 603–6
Red flags in skin rash
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Systemic symptoms
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Fever
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Altered mental state
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Co-morbidity: immunocompromised
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Large area of skin involvement
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Mucosal or ocular involvement
Causes of maculopapular rash
A maculopapular rash in the absence of fever or systemic illness does not constitute an urgent illness.Symptomatic treatment in the absence of a definitive diagnosis may be required.
Afebrile
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Central distribution: drug eruption; pityriasisrosea; viral infection
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Peripheral distribution: scabies; atopic dermatitis
Febrile
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Central distribution: viral exanthema (measles, rubella, rubeola, roseola- circular to elliptical rose-red macules or papules involving trunk, occasionally surrounded by a white halo, erythema infectiosum-slapped cheeks, with bright red erythema, infectious mononucleosis, enteroviral, adenoviral and arboviral infections); drug reaction; Kawasaki disease
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Peripheral distribution: Stevens-Johnson syndrome; erythema multiforme; early meningococcaemia; early toxic shock syndrome; secondary syphilis; Lyme disease
Causes of STAR complex
(sore throat, arthropathy, and skin rash)
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Rubella
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Parvovirus B19 (slapped cheek syndrome; viral prodrome, slapped cheeks, peri-oral pallor, sparing of palms and soles)
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Hepatitis B
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Adenovirus
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Echovirus
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Coxsackie
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Epstein-Barr virus
Causes of purpura
Loss of dermal vascular connective tissue
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Senile purpura
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Steroid therapy
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Vitamin C deficiency
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Hereditary connective tissue diseases: Ehlers-Danlos syndrome; Marfan syndrome
Vascular
Vessel wall damage
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Mechanical: trauma, suction to skin, stasis, factitious
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Anoxic-microvascular obstruction: consumption coagulopathies: DIC, TTP, haemolyticuraemic syndrome; purpurafulminans; fat embolism; myeloproliferative disease
Inflammatory vasculitis (Palpable purpura)
Vasculitis/arteritis
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Hypersensitivity vasculitis: Henoch-Schonleinpurpura (tetrad of purpura, abdominal pain, renal disease and arthritis or arthralgia); collagen vascular disease
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Leukocytoclasticvasculitis
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Infective vasculitis: meningoccal, streptococcal, gonococcal
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Dysproteinemias
Rickettsial infections
Non-vasculitic (pseudo-purpura)
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Angiokeratoma
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Cherryangioma
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Pyogenic granuloma
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Kaposi’s sarcoma
Intravascular (haematological)
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Thrombocytopenia
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Functional platelet disorders
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Coagulopathies
Causes of generalised itching
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Dry skin (xerosis)
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Atopic dermatitis (itchy, dry erythematous scaly patches with vesicles and exudation; flexural dermatitis with lichenification, egantecubital and popliteal fossae; involvement of eyelids; cheilitis; white dermographism; recurrent conjunctivitis, keratoconus, anterior and/or posterior subcapsular cataracts; personal/family history of atopic disease; increased susceptibility to viral infections; enhanced sensivity to irritation by detergents, wool and certain chemicals)
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Contact dermatitis
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Drugs: statins, ACE inhibitors, opiates, barbiturates, recreational drugs, antidepressants, oral retinoids
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Urticaria
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Conjugated hyperbilirubinemia (cholestasis)
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Scabies: linear burrows, erythematous papules, vesicles, excoriations, crusts and pustules which are symmetrical in distribution and typically involve the inter-digital web spaces, flexor aspects of the wrists, axillae and the waist, showing a predilection for warm moist areas. Thick scaly plaques characterize Norwegian or crusted scabies.
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Chronic kidney disease
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Biliary obstruction
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Papularurticaria
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Animal mites
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Flea bites
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Lice infestations (Pediculosis)
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Iron deficiency anaemia

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