بسم الله الرحمن الرحيم

PRURITUS د. رزان

Objectives: 1. to define pruritus. 2. to classify its causes.

PRURITUS Definition: PRURITUS : Itching= Unpleasant sensation that provokes the desire for scratching. Scratching: Is the action taken in response to itching. Itching= sensation. Scratching=action.

P. is the commonest dermatologic complaint. It is not a diagnosis. P. is a symptom that may be caused by many conditions.

Itch pathway Mediatedors: mainly ;histamine from mast cell. other mediatedors: vasoactive chemicals like serotonin, bradykinin. Itch nerve ending are lie very close to dermo-epidermal junction. Itching sensation is transmitted via C fibers(slow conduction speed) through spino-thalamic tract to the thalamus & on to a cortical representation

How to analyze itching? Site Duration Onset Diurnal variation. Severity. Precipitating factors. Aggravating factors. Alleviating factors. Associated features.

*Classification: Itchin g Localized Acute Chronich. Generalized

Generalized Pruritus:- Acute Generalized pruritus: Wide spread urticaria. Scabies. Acute allergic contact dermatitis. Drug eruption. Pediculosis corporis. Acute erupted lichen planus.

pure cutaneous disease Chronich-Generalized itching pure cutaneous disease systemic cause

A) Pure cutaneous causes of chronich generalized itching; Atopic dermatitis. Seborhoic dermatitis. Senile pruritus. Dry skin. Dermatitis herpitiformis. Cutaneous T cell lymphoma(Mycosis fungoides).

B) Systemic causes: Neuro-psychogenic pruritus. Endocrine disease; a-Hyper thyroidism & Hypothyroidism; b-D.M. c-Pregnancy; (Obstetric Cholestasis.). Liver disease; a- Cholestatic jaundice; b-Primary Biliary Cirrhosis. c-Chronic active hepatitis(HBV & HCV). Renal disease; -Chronic renal failure; Blood disease; a-Polycythaemia rubra vera. b-Iron deficiency anaemia; c-Leukaemia; lymphoma, Myeloma. 6. Malignancy; a-Hodgkin's disease; b-Carcinoma; Ca. breast, bronchus, stomach & pancreas. 7. HIV .

Localized chronic itching: Lichen planus. Chronic contact dermatitis. Nurodermatitis Pomphylax Discoid eczema Varicose dermatitis. Asteatotic eczema. Lichen sclerosus it atrophicus. Paget disease.

Localized –acute itching: Insect bite Acute contact dermatitis. Photodermatitis Fixed drug eruption. Pediculosis pubis& capitis. Worm infestation (Oxyuriasis).

Diagnosis: Mainly clinical Simple Investigations. Sophisticated Investigations. According to the suspected cause.

Treatment: A-General measures: Reassure. Explain the condition. Treat the primary underlying cause. Avoid aggravating factors(scratching). Gentle skin care.

B-Topical measures: Topical Emollients agent on skin. Topical antihistamine. Topical CS (have potent anti-pruritic effect). Tacrolimus and pimecrolimus. Other therapies to decrease itching include: Topical menthol 1%, camphor.

C-Systemic therapies Systemic H1 blocking anti histamines (either sedative or not). -Systemic CS (short course small dose). D-Others: Phototherapy: UVB & PUVA.

Thank you