Page 170 - fourth year book

SKIN DISEASES

2. Erythematous or non-erythematous. Erythematous lesions are
usually indicative of acute inflammation.

3. Surface features

 Normal/ smooth: the surface is not different from the surrounding
skin and feels smooth.
 Scaly: dry/flaky surface due to abnormal stratum corneum with
accumulation of or increased shedding of keratinocytes.

 Exudate: serum, blood, or pus that has accumulated on the surface.
 Crust: dried serum, pus or blood
 Excoriation: localized damage to the skin due to scratching.
 Lichenification: thickening of the epidermis with increased skin
markings due to persistent scratching.

4. Types of lesions (fig.1)

I. Primary lesions:

They are classified into: Macular lesions and elevated lesions

A. Macules : are flat, non-palpable lesions usually less than 1cm in
diameter Macules represent a change in color or surface texture and
are not raised above the skin surface. A patch is a large macule.
Examples include (freckles, flat moles, tattoos, port-wine stains, and

the rashes of rickettsial infections, rubella, measles, and some allergic
drug eruptions).

B. Solid elevated lesions:

1. Papules: are elevated lesions usually less than 1 cm in diameter
and without dermal and/or sub dermal extension that can be felt

or palpated. Examples include nevi, warts, lichen planus, insect
bites, seborrheic and actinic keratoses, some lesions of acne, and
skin cancers.

2. Nodules: are firm lesions that extend into the dermis or
subcutaneous tissue and elevated 1-2 cm in diameter. Examples
include cysts, lipomas, and fibromas.

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