pruritis

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:

Generalized Pruritus:-

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

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