Disorder of eccrine sweat glands • Present all over the body especially on the palms, soles and in axillae. • Multiple factors are controlling rate of sweating-temp., hormones, emotions, gustatory. • Disorders: • Generalized hyperhidrosis • Hypo and anhidrosis • miliaria Miliaria • Spillage of sweat into dermis due to obstruction and rupture of eccrine sweat ducts. • Occurs – hot humid climate • Variation according to level of rupture: • Miliaria crystallina (rupture below stratum corneum) – Tiny clear noninflammed vesicles. • Miliaria rubra(rupture in epidermis) – Pricking or burning sensation with small erythematous papules surmounted by vesicles. • Miliaria profunda(rupture in dermoepidermal juncn.) – Larger erythemaouts papules treatment • Avoid humid and humid places • Avoid synthetic garments • Calamine lotion • Severe cases: short course of mild topical steroid Disorder of apocrine gland • Present in axillae, nipples, periumbilical area, perineum and genitalia. • Duct of the gland connects into mid portion of the hair follicle . • Becomes functional just before puberty. Disorder • Hidradenitis suppurtiva (apocrine acne) • Cause unknown • Microbs like staph. Aureus, anaerobic strpt. And bacteroides are often found in the lesions but their role in the pathogenesis is doubtful • Lesions seen are ndules, pustules, cysts and sinuses with interconnecting bridges. Comedones frequently seen. • Site-axilla, groins and perianal region. • Treatment: • Severe cases large area of vault of axilla is excised to remove apocrine glands to prevent recurrences. • Medical : – Systemic antibiotics like tetracyclines and erythromycin) – Systemic antiandrogen and retinoids – Isotretinoin – Incision and drainage – Intralesional inj. Of triamcinolone ABNORMAL VASCULAR RESPONSE • Both exogenous and endogenous stimuli can trigger vascular responses in skin. • At the beginning the epidermis is normal and later it may show changes in the form of necrosis mainly due to vascular compromise. • Different forms: – Vascular dilatation –erythema – Dermal and subcut. Oedema –urticaria and angioedema – Extravasation of blood due to vessel wall inflammation -vasculitis ERYTHEMA MULTIFORME • As its name implies, this is a reaction pattern of multiform erythematous lesions. • PROVOKING FACTORS IN ERYTHEMA MULTIFORME • Herpes simplex infections • Other infections, e.g. mycoplasma ,hepatitis A,histoplasmosis • Bacterial infections • Drugs, especially sulphonamides, penicillins ,carbamazepine, phenitoin and barbiturates (most frequent in SJS-TEN COMPLEX) • Internal malignancy or its treatment with radiotherapy • SLE,graft vs host rxn.,lymphoreticular malignancies • Idiopathic (5%) • The multiform erythematous lesions may be urticaria-like and some have obvious 'bull's-eye' or 'target' lesions. • Blisters may be seen in the centre or around the edges of the lesions • In some cases blisters dominate the picture; the Stevens- Johnson syndrome-toxic epidermal necrolysis comples(SJS- TEN complex) is severe bullous erythema multiforme with emphasis on mucosal involvement including the mouth, eyes and genitals, with constitutional disturbance. • Oral mucosa: hemorrhagic crusting of lips. Bullae which rapidly rupture to form erosions covered with grayish white slough • Eyes: purulent conjunctivitis, corneal erosions • Genital mucosa: erosion s and complicated by urinary retention • Nasal mucosa: erosions • SJS-TEN complex is clinically graded into • SJS- when the body surface area involves<10% • SJS-TEN- when BSA 10-30% • TEN- >30% • Management • Usually no treatment is required although symptomatic relief can be obtained with simple dressings. • Stevens-Johnson syndrome can be treated with a short course of intravenous immunoglobulin. Corticosteroids are best avoided. ERYTHEMA NODOSUM • This characteristic reaction pattern is due to a vasculitis in the deep dermis and subcutaneous fat. • Clinical features • Painful, palpable, dusky blue-red nodules • most commonly seen on the lower legs. • Malaise, fever and joint pains are common. • The lesions resolve slowly over a month, leaving bruise-like marks . • PROVOKING FACTORS IN ERYTHEMA NODOSUM • Infections •Bacteria (streptococci, tuberculosis, brucellosis and leprosy), viruses, mycoplasma, rickettsia, chlamydia and fungi • Drugs •e.g. Sulphonamides and oral contraceptives • Systemic disease •e.g. Sarcoidosis, ulcerative colitis and Crohn's disease • Management • The underlying cause should be determined and treated. Bed rest and oral NSAIDs may hasten resolution. Tapering systemic corticosteroid courses may be required in stubborn cases. urticaria • Also known as hives. • Eruption characterized by transient usually pruritic wheals due to acute dermal oedema from the extravascular leakage of plasma. • Angioedema signifies larger areas of oedema involving the dermis and subcutis. Aetiopathogenesis • Immune • Non immune • Lesion occurs due to release of biologically active substances from mast cells particularly histamine. • Histamine causes vasodilatation and increased vascular permeability. Different pathways involved • Antigen induced , IgE mediate histamine release from tissue mast cells causing immediate hypersensitivity. • Mast cell degranulation through the classical complement pathways. • Direct mast cell degranulation by certain drugs and chemicals Preformed mediators in granules • Histamine bronchoconstriction, mucus secretion, vasodilatation, vascular permeability • Tryptase proteolysis • kininogenase kinins and vasodilatation, vascular permeability, edema Newly formed mediators • leukotriene B4 basophil attractant • leukotriene C4, D4 same as histamine but 1000x more potent • prostaglandins D2 edema and pain • PAF platelet aggregation and heparin release: microthrombi Classification of urticaria Group Example • Chronic • Idiopathic • Acute • Ige mediated e.g food allergy,drug reaction. • Physical • Dermographism,cholinergic, cold,solar,heat,delayed pressure. • Contact • Food allergans • Pharmacological • Aspirin ,opiates,non streroidal drugs, • Systemic • LE,lymphoma,thyrotoxixosis infections, • Inherited • Heriditary angioedmea. • others • Insect bite ,mastocytosis. Clinical presentation • Common is chronic idiopathic form. • No cause is found • Itchy pink color wheals appear either as papules or plaques anywhere in the skin. • Typically they last for less than 24 hours and dissappear without a trace . • Wheals may be round ,annular or polycyclic and vary in diameter from few mm to several cm. • Their number can vary from few to many. • Angioedema usually with oedema of the tongue and lips may occur. • Resolves spontaneously within few months. Acute form • Sudden form may be due to Ige mediated type 1 reaction. • Patients can often identify the allergens. • Commonly it is a food or a drug. • Acute urticaria is commonly caused by a variety of infections, medications, food allergies, physical stimulants, chemicals, chronic inflammatory diseases, and insect bites, as follows : – Recent infection from a viral syndrome or an upper respiratory tract illness (39%) – Medications (eg, ACE inhibitors, aspirin, nonsteroidal anti-inflammatory drugs, sulfa-based drugs, penicillins, diuretics, opioids, polymyxin B) – Food and food additives (eg, nuts, fish, shellfish, eggs, chocolate, strawberries, salicylate, benzoates) – Parasitic infections (eg, Ascaris, Ancylostoma, Strongyloides, Echinococcus, Trichinella, Filaria) – Physical stimulants (eg, cold, pressure, aquagenic) – Chemicals (eg, latex, ammonium persulfate in hair chemicals) – Intravenous radiocontrast media – Arthropod bites wheal Physical urticaria • Cold ,heat sun exposure ,pressure and even water can induce urtricaria . • Dermographism may be found. • Wheal in cholinergic urtricaria is itchy with small papules that appears in response to sweating as induced by exercise ,heat,emotion ,or spicy food.it may last for few mins to few hours . Dermographism Hereditary angioedema • Autosomal dominant. • Usually fatal • Episode of angioedema involving larynx and gi tract. • Due to defficiency of c1 esterase inhibitor that causes the activation of complement pathway and accumulation of vasoactive mediators. • In acute condition fresh frozen plasma are given . • In long term danazol is given . Angioedema Management • Underlying cause should be eliminated. • Desensitization • Main stay of treatment is with antihistaminics. • Cetirizine (Zyrtec) • Second-generation antihistamine with markedly reduced sedative effects and reduced anticholinergic effects. Forms complex with histamine for H1 receptor sites in blood vessels, GI tract, and respiratory tract. • Adult • 5-10 mg PO • Fexofenadine (Allegra) • Competes with histamine for H1 receptors on GI tract, blood vessels, and respiratory tract, reducing hypersensitivity reactions. Does not sedate. • SR: 180 mg PO Histamine H2 antagonists • Cimetidine (Tagamet) • H2 antagonist that when combined with an H1 antagonist may be useful in treating itching and flushing in urticaria and contact dermatitis that do not respond to H1 antagonists alone. Use in addition to H1 antihistamines. • 300 mg PO qid • Corticosteroid:used occassionaly in severe cases and in angioedema and urticarial vasculitis. Prednisone • Immunosuppressant for treatment of autoimmune disorders; may decrease inflammation by reversing increased capillary permeability .Stabilizes lysosomal membranes and suppresses lymphocytes and antibody production. • 0.5-2 mg/kg/d PO; taper as condition improves; single morning dose is safer for long-term use, but divided doses have more anti-inflammatory effect Adrenaline • Acute airway obstruction or anaphylactic shock • Adrenaline together with an antihistaminics chlorpheniramine should be given i.v slowly. • Adrenaline dose 0.5-1 mg 0.5-1 ml of 1/1000.