Cutaneous Reaction To Physical Agents PDF

Cutaneous Reaction To Physical Agents Dr. Sarah Raed Dermatologist  Reaction to cold ØReaction to abnormal cold exposure : May occur in any individual over exposed to excessive cold. üExample : frost bite üIt started as painful erythema, swelling or even blister….. If persi...

Cutaneous Reaction To Physical Agents Dr. Sarah Raed Dermatologist  Reaction to cold ØReaction to abnormal cold exposure : May occur in any individual over exposed to excessive cold. üExample : frost bite üIt started as painful erythema, swelling or even blister….. If persist gangrene and even spontaneous amputation of the affected parts. Frost bite Frost bite with amputation  Abnormal reaction to usual cold exposure vOccurs only in small susceptible proportion of the population. v probably genetically predispose. vExample: chilblain, cryoglobullinemia and others.  Perniosis (chilblains) o An abnormal vascular response to cold exposure. oChilblains are painful, inflammatory lesions provoked by exposure to cold. oThey particularly affect older children and young adults. oThe lesions occur on the fingers, toes and occasionally elsewhere. oIt presented as raised, dusky red swellings. oare painful and/or itchy. Chilblain  Treatment 1. Protection from cold. 2. Wearing warm, dry clothing during cold weather to protect hands, feet, and ears 3. Anti-inflammatory drugs. 4. Topical steroids, Antihistamines may relieve itch 5. Vasodilator : nifidipine (20–60 mg) three times daily, hastens healing time and reduces the risk of relapse 6. exercise to keep warm and improve circulation 7. Cessation of smoking and other vasoconstrictors  Reaction to the heat 1- Erythema ab igne: §It is occurs in patients exposed frequently to Infra red radiation from heat sources for long time causes injury to the skin. §It presented as brownish-red reticulate pigmentation. §Some patients may complain of mild itchiness and a burning sensation. Treatment The source of chronic heat exposure must be avoided. If the area is only mildly affected with slight redness, the condition will resolve by itself over several months. If the condition is severe and the skin pigmented and atrophic, resolution is unlikely. In this case, there is a possibility that squamous cell carcinomas may form. If there is a persistent sore that doesn't heal or a growing lump within the rash, a skin biopsy should be performed to rule out the possibility of skin cancer. Abnormally pigmented skin may persist for years. Treatment with topical tretinoin or laser may improve the appearance Erythema ab igne  2-Miliaria ‫گةرموشك‬ üA common form of sweat rash is due to blockage of the sweat gland pores or ducts. Types: 1. Miliaria Crystallina: Tiny, thin walled vesicles that arise from blockage at the pore near the surface. Affect children 2. Miliaria Rubra ( prickly heat ): Bedridden patients §The most common type § red, inflamed papules § occur due to blockage lower in the duct. In the middle of epidermis 3- miliaria profunda: Blockage at or below the dermo-epidermal junction) following repeated episodes of miliaria rubra.. Asymptomatic flesh colored firm 2-3 mm papules.  Treatment Avoidance of hot exposure. Wearing light cotton clothes. Cool air, cool water compresses, cool baths Vit c orally , antihistamines, topical emollients or mild topical steroid. q The sun emits a continuous band of energy over a wide range of wavelengths, but it is only the UVR (200–400 nm) that is of major importance. qThree segments of UVR are recognized:  UVA q 320–400 nm. qmainly causes: 1. immediate pigment darkening 2. photoallergic reaction.  UVB Ø 290–320 nm Ømainly causes: 1. sunburn. 2. phototoxic reaction. 3. delay pigment darkening. 4. premalignant and malignant skin conditions.  UVC q200–290 nm. q mostly filtered out by the ozone layer. qonly become biologically important if the ozone layer became seriously depleted. Normal to Excessive Sun Exposure Reactions 1. Acute effects: A. Skin pigmentation: Immediate pigment darkening and delayed tanning. A. Sun burn. B 2. Chronic effects: A. photo aging of the skin: § Excessive wrinkling. § Skin atrophy Lentigines § Solar lentigines. § Solar elastosis. - § Senile comedones. Senile comedone § Telengiectasia. § Poikiloderma of Civatte. B. premalignant and malignant skin conditions: These are caused mainly by UVB, ex. actinic keratosis, basal cell carcinoma, squamous cell carcinoma and malignant melanoma.  Skin Pigmentation Immediate pigment darkening: This is started few minutes and last for few, hours after sun exposure. It is caused by photo-oxidation and darkening of the preexisting melanin without new melanin formation. Delayed tanning: This is usually started few hours after sun exposure and peak in 72 hours and last for 2-4 weeks. It is caused by UVB leading to hypertrophy and hyperplasia of melanocytes and new melanin formation.  Sunburn Ø This is a very common condition that occurs when the patient exposed to excessive sunlight. It is mainly caused by UVB and rarely by UVA. Ø It usually starts few hours after sun exposure as erythema associated with burning sensation, oedema and swelling. Vesicles and bullae may occur in severe conditions. ØSevere systemic symptoms may occcur. Treatment: Øcold bath and cold dressing Ø topical steroids Øantihistamines Ø Antiprostaglandins: indomethacin or aspirin orally.  Photosensitivity reactions Skin can become sensitized to a specific part of the solar spectrum by chemical agents that reach it either via the systemic route or after contacting the skin topically.  Photosensitivity consists of two types: Phototoxicity: this can occur in any patient when exposed even for the first time to sufficient dose of the offending drug that is followed by sun exposure. The patient develops sunburn like picture clinically. Photo-allergic reaction: Øoccurs only in predisposed individuals and needs previous exposure and sensitization. ØIt appear clinically as dermatitis like reaction on re-exposure even to small dose of the drug i.e. dose independent. Photo-allergic reaction: Comparison between phototoxic and photoallergic reaction Fe ature Phototoxic re action Pho to alle rg ic re actio n Incidence High (All people) Low (Predisposition) Amount of agent Large Small required Onset of reaction Minutes to hours 24-72 h Distribution Sun-exposed skin Sun-exposed skin; may only spread to unexposed areas More than one No Yes exposure to agent required Clinical Resembles exaggerated Dermatitis characteristics sunburn or blisters Immunologically No Yes; type IV mediated ØSome common photosensitizing agents are Tetracyclines Phenothiazines Amiodarone Nalidixic acid = phytophotodermatitis ØPhytochemical reactions are photosensitivity responses that result from contact with plants or their products on areas exposed to the sun. Ø Example : psoralens are found in some fruits, such as the figs, citrus fruits  Abnormal Reactions to Sun Exposure (Photodermatoses) I. Metabolic diseases: ex. Porphyria, xeroderma pigmentosum, pellagra. 2. Drug induced (topical and systemic drugs). 3. Diseases aggravated by sunlight: - Actinic lichen planus -Erythema multiforme -Lupus erythematosus 4. Idiopathic photodermatosis: Polymorphic light eruption Solar urticaria Chronic actinic dermatitis Hydroa aestivale (summer prurigo of Hutchinson) Hydroa vacciniform Juvenile spring eruption Actinic reticuloid  Polymorphic light eruption Ø The commonest idiopathic light induced skin disease. ØThe initial symptoms include burning, itching and erythema, on sun exposed areas (face, V area of chest, back of hands, extensors of forearms, lower legs), usually hours after sun exposure throughout the spring and summer months, and persists for several days. ØThe disease may begin at any age predominately between 20-40ys, Lesions usually heal without scarring. Light sensitivity may decrease with repeated sun exposure, a condition referred to "hardening" There are several morphological types: ØPapular type (the commonest form), Papulovesicular type, Plaque type, Erythema multiforme type, urticarial type Diagnostic Criteria for Polymorphic Light Eruption 1. Delayed occurrence of skin lesions after ultraviolet (UV) exposure (within hours to days; but not