Differential diagnosis of very itchy skin

Author: A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, February 2016.

Introduction

Itch is defined by a desire to scratch.

An acute or chronic itchy rash is most often due to dermatitis/eczema. Dermatitis can be primary, or secondary to scratching.

Stages include:

If clinical diagnosis of an itchy skin problem is uncertain, consider performing the following tests:

General treatments for itchy skin conditions may include:

Differential diagnosis of very itchy skin

Consider:

Very itchy skin with localised rash

Contact dermatitis:

Head lice:

Insect bites / papular urticaria:

Lichen planus:

Lichen sclerosus:

Lichen simplex:

Pompholyx (dyshidrotic eczema):

Venous eczema:

Mildly itch skin with localised rash

Asteatotic eczema:

Psoriasis:

Seborrhoeic dermatitis:

Very itchy skin with generalised rash

Autoeczematisation:

Bullous pemphigoid:

Dermatitis herpetiformis:

Atopic dermatitis (eczema):

Discoid eczema:

Erythroderma:

Lichen planus:

Mycosis fungoides (T-cell lymphoma):

Neurodermatitis:

Nodular prurigo:

Scabies:

Transient acantholytic dermatosis / Grover disease

Urticaria:

Mildly itchy skin with generalised rash

Psoriasis:

Xerotic eczema:

Localised itchy skin without rash

May have secondary lesions due to scratching: erosions, purpura, lichen simplex and secondary infection. Localised itch is often neuropathic/neurogenic. If scalp itchy, look carefully for head lice and their egg cases.

Brachioradial pruritus:

Meralgia paraesthetica:

Notalgia paraesthetica:

Vulval itch

Scrotal itch

Generalised itchy skin without rash

Examine carefully for scabetic burrows.

Pruritus/prurigo of pregnancy:

Systemic disease:

Related information

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