Erythema refers to redness of the skin that blanches under pressure. It is caused by increased blood flow within subpapillary plexus or increased visibility due to changes in adjacent tissues. Common causes of erythema include drug reactions, viral infections, streptococcal infections, systemic diseases like lupus erythematosus or lymphoma. Target lesions seen in erythema multiforme consist of three zones - a dark or blanched center surrounded by a pale zone which is surrounded by an outer rim of erythema. Treatment of erythema multiforme involves treating any underlying cause, using systemic antibiotics or steroids, and antivirals to prevent recurrence.

1. Erythema

3. It is due to an  in blood within subpapillary plexus or to an  visibility due to changes in adjacent tissues.

4. Diffuse erythematous eruptions due to drug sensitivity, virus exanthems, streptococcal infection or systemic dis., e.g. LE or lymphoma.

6. Pregnancy & liver diseases.

7. With systemic dis., e.g. SLE, Rhoid arthritis.

9. IF studies demonstrate IgM & C3 in the walls of superficial dermal vessels, in lesions less than 24 hrs old.

12. steredcenter (bull’s-eye) that is surrounded by a second, pale zone.

14. Drugs: e.g. sulphonamides, sulphones, contra-ceptive pills.

15. Infections:

16. Virus: H. simplex, vaccinia, AIDS, hepatitis B, Orf, Milker’s nodes.

17. Mycoplasma, histoplasmosis.

20. Malignancies, e.g. carcinoma, lymphoma, leukemia.

21. Pregnancy, autoimmune progesterone dermatitis.

23. The lesions appear in successive crops, each fades in 1-2 wks.

24. The extremities & face are commonly affected.

25. Erosions of oral mucous membranes may occur rarely.

31. High fever, malaise & arthralgia.

32. Generalized bullous & maculopapular lesions occur with affection of oral mm in all cases in the form of extensive bullae formation followed by erosions.

33. New crops of lesions develop over a period of 3-4 wks.

34. Many organs may be affected: severe catarrhal or purulent conjunctivitis, genital mucosa, pneumonitis & renal affection.

37. Acute onset & self-limited episodic course.

38. Duration must be less than 6 ms “for each episode”.

39. Typical & fixed skin lesions >7 days.

41. Systemic antibiotics.

42. Minor cases require only symptomatic treatment.

43. Major cases may require systemic steroids: 30-60 mg prednisone daily.

44. Acyclovir may be used as a prophylactic measure to prevent recurrence after herpes simplex.

46. It has been called Lyell’s syndrome which includes also cases of SSS syndrome.

48. Erythema, which may be morbilliform or diffuse, occurs with +veNikolsky sign followed by large flaccid bullae & detachment of large areas of necrotic epidermis leaving large, raw, painful areas.

49. Mucous membranes may be extensively involved. Ocular conjunctiva is involved in 85% of pts.

52. GVHD.

53. Infections, e.g. Herpes virus.

54. Neoplasms, e.g. Hodgkin’s leukemia.

55. SLE.

57. Local treatment:

58. Extensive debridement of nonviable epidermis followed by immediate wound cover with biological dressings.

59. Hyperbaric oxygen.

60. Systemic steroids.

61. Plasmapheresis.

62. High dose of IV immunoglobulins.

64. Onset is in the first 3 days of life in 90% of the cases and is extremely rare at birth.

67. Itchy, pale in center  pink superficial plaques, resolve over hours without a mark.

73. Painful, rather than pruritic and take longer time to resolve.

78. Exercise-induced anaphylaxis

79. Localized heat urt.

80. Solar urt.

81. Vibratory angioedema

82. Adrenergic urt.

83. Aquagenicurt.

84. Cholinergic urt.

85. Cold urt.

86. Delayed pressure urt.III. Contact urticaria: biologic, chemical. IV. Urticarialvasculitis(proved by skin biopsy) V. Angioedema(without wheals)

87. Classification 1. Ordinary urticaria (72%) - Acute - Chronic (often idiopathic) 2. Immune-complex urticaria Urticarialvasculitis (2.1%). 3. Physical & cholinergic (20%).

88. Classification 4. Contact urticaria 5. Angio-edema - Hereditary “C1 esterase INH deficiency” (0.5%) - Acquired - ACEI-induced - Episodic angio-edema with eosinophilia 6. Diseases with urticaria as a component

91. Acute allergic urticarias: ® Substance P.Drugs (Aspirin, NSAIDs, Polymyxin) Radiocontrast media Anaesthetic agents

92. Urticarias Potential Provoking Factors 1. Drugs: penicillin, aspirin, sulfonamides, NSAIDs, …. 2. Foods (eggs, fish, strawberries, milk, … etc.) & food additives (Azo dyes, benzoates, penicillin).

93. Urticarias Potential Provoking Factors (Cont.) 3. Inhalants: e.g. pollen grains, house dust, feathers. 4. Infections e.g. focal sepsis in tonsils, teeth or sinuses, or urinary tract infections. Recently, Helicobacter pylori has been suggested.

94. Urticarias Potential Provoking Factors (Cont.) 5. Infestations: Intestinal worms. 6. Emotional stress especially in cholinergic urticaria. 7. Systemic disease: SLE, lymphomas, thyrotoxicosis.

96. Sudden appearance of itchy red transient wheals.Episodes of wheals “wheal come & go” for duration Less than 6 wks Acute More than 6 wks Chronic

99. Physical urticarias: appear within 10 min. of the trigger stimulus and clear within an hr.

100. Contact urticaria: arises within 10-30 min. of exposure to the contactant and settles over 2 hrs.

102. General examination of associated systemic disease

104. The autologous serum skin test (ASST):

105. High sensitivity & high specificity.

106. Reduced by oral antihistamines.

107. Decrease or absent peripheral blood basophils “clinical marker”.

108. Basophil histamine release assay is most specific.

113. They may present with wheals or angioedema &, very rarely, anaphylaxis.

118. Due to cryoglobulins

119. FamilialIV. Solar V. Aquagenic VI. Contact urticaria

121. DD:

122. Linear asymptomatic reddening commonly seen in healthy people after scratching.

125. Cholinergic sympathetic innervation of sweat glands is involved.

127. Mainly in palms, soles and lower back.

129. Poor response to antihistamines.

131. Angioedema or anaphylaxis may also occur when it is severe.

133. Normocomplementemicurticarialvasculitis is usually idiopathic.

137. Blood eosinophilia should prompt stool examination for parasitic infestations.

139. Dietary exclusion.

140. Oral challenge may reveal food additives as a cause of chronic urticaria.

146. Management of chronic ordinary urticaria Pharmacological therapy SECOND LINE Special indications Corticosteroids (for severe ordinary or delayed pressure urticaria) Short term use only Epinephrine (severe throat angioedema or anaphylaxis only) Others (as determined by history & investigations)

147. Management of chronic ordinary urticaria Pharmacological therapy THIRD LINE Specialist use only Immunotherapy (severe refractory autoimmune urticaria only)