The lecture has been given on Dec. 19th, 2010 by Dr. Mohammad Yousif.

1. Pruritus “Itching”

3. It is the most common symptom of inflammatory skin diseases.

5. Pruritus Without primary skin lesions But with secondary skin lesions, e.g. ulcer, excoriations, lichenification, hyperpigmentation, etc. Generalized pruritus without 1ry skin lesions Manifestations of syst. dis. Generalized idiopathic pruritus

6. Causes of Pruritus

7. Causes of pruritus I) Pruritus from skin diseases These diseases often have characteristic lesions and locations. However, rubbing and scratching may conceal the primary lesions.

8. I) Pruritus from skin diseases (Cont’d) A) Severely pruritic dermatoses Scabies / phthirus pubis DH LP Urticaria Contact dermatitis Atopic dermatitis Drug eruptions PUPP of pregnancy Herpes gestationis Mycosis fungoides No scratch marks 10

9. I) Pruritus from skin diseases (Cont’d) B) Moderately pruritic dermatoses Seb. Dermatitis. Polymorphous light eruption. Urticaria pigmentosa. Fungal infections. Asteatotic eczema (xerosis): aggravated by low humidity during winter (winter itch). 5

10. Causes of pruritus (Cont’d) II) Exogenous causes of pruritus Sunburn. Chilblains. Aquagenic pruritus. Insect bites / animal mites. Detergents / fiberglass. 5

11. Causes of pruritus (Cont’d) III) Systemic causes of pruritus: Systemic causes of pruritus can be summarized by the mnemonic BLINKED.

15. Psychogenic pruritus, in contrast to organic pruritus, DOES NOT awaken patients from their sleep

17. Lymphomas, leukemias.

18. Internal malignancy.

20. Delusions of parasitosis.

21. Neurotic excoriations.

23. Hyperthryoidism (4-11% of patients).

24. Hypothyroidism (2ry to xerosis).

26. Approaching the pruritic patient The approach to the patient with generalized pruritus without primary skin lesions is in the same manner as a patient with factitious dermatosis. Both are diagnoses of exclusion, i.e. all organic causes must be excluded within reasonable limits.

27. 15 points should be discussed in the history

36. Hot water, harsh soap dryness dermatitis.

42. Enlargement of LN, spleen, liver  lymphoma.

43. Rectal examination and pelvic examination (female)  malignancy.

44. Oral candidiasis  LN++  HIV.

46. Renal function tests: urea, creatinine.

47. Liver function tests: alkaline phosphatase (best screening test), bilirubin. Serum antimitochondrial antibody test is highly sensitive and specific for diagnosis of primary biliary cirrhosis (PBC).

48. Thyroxine and TSH.

49. Feces for: parasites, occult blood (> 40 years).

50. Chest X-ray.

54. Morphine relieves pain but can produce itching. Its antagonist “Naloxone” inhibits itch but lowers pain threshold.

59. Therapeutic approach I) General recommendations Diagnosis and treatment of underlying cause. Prevention of scratching to stop the vicious cycle: the more the patient scratches, the greater the secretion of mediators  exacerbates pruritus.

61. Avoid contact with pruritus-enhancing substances, e.g. very hot water   histamine secretion. Bathing should be in luke warm or cold water.

62. Avoid exposure to heat & excessive persipiration  stimulates C fibers which transmit pruritus.

64. Alcohol, phenol & camphor  local anesthetic effects.

65. Calamine lotion.2. Anesthetics: EMLA ointment, pramoxine. 3. Doxepin 5% cream in atopic dermatitis. 4. Steroids and liquid aspirin. 5. Capsaicin: it depletes neuropeptide substance P from unmyelinated C sensory neurons. 6. Crotamiton (Eurax).

66. Therapeutic approach III) Physical treatment 1. UVB is effective in uremic or hepatic pruritus. 2. Narrow-band UVB is effective in pruritus of atopic patients. 3. PUVA is effective in treatment of pruritus due to aquagenic pruritus and atopic dermatitis. Phototherapy stabilizes mast cells preventing release of lymphokines from lymphocytes.

67. Therapeutic approach IV) Systemic treatment 1. Oral antihistamines

72. Cholestyramine (Questran).

73. Naloxone (opiate antagonist – Naxone).

75. Oral cholestyramine.

76. Heparin.

77. Thalidomide.

78. Erythropoietin.

79. UVB.

80. Renal transplant.