Page 169 - fourth year book

SKIN DISEASES

Interpretation of Patch Test

The result of patch test is interpreted as follows:

1+: Erythema only.

2+: Erythema and papules.

3+: Erythema, papules and small vesicles.
4+: Large vesicles, bullae, and severe local reaction besides

erythema.

A proper skin examination should be performed in good light;
preferably in day light.

While describing skin lesions, the following features should be
identified:

1. Sites involved and distribution: - if lesions are affecting both sides
of the body symmetrically, it probably could have an endogenous
origin (e.g. eczema, psoriasis, acne ...) but if it involves
predominantly one side of the body, usually it could be of external

cause (e.g. bacterial, fungal, contact eczema).

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