Skin diseases, particularly infectious skin diseases, are very common. They must be treated individually or collectively, but must also be considered as indicators of the sanitary condition of a population. A high prevalence of infectious skin diseases may reflect a problem of insufficient water quantity and lack of hygiene in a population.
- Observe the type of lesion:
- Macule: flat, non palpable lesion that is different in colour than the surrounding skin
- Papule: small (< 1 cm) slightly elevated, circumscribed, solid lesion
- Vesicle (< 1 cm), bulla (> 1 cm): clear fluid-filled blisters
- Pustule: vesicle containing pus
- Nodule: firm, elevated palpable lesion (> 1 cm) that extend into the dermis or subcutaneous tissue
- Erosion: loss of the epidermis that heals without leaving a scar
- Excoriation: erosion caused by scratching
- Ulcer: loss of the epidermis and at least part of the dermis that leaves a scar
- Scale: flake of epidermis that detaches from the skin surface
- Crust: dried serum, blood, or pus on the skin surface
- Atrophy: thinning of the skin
- Lichenification: thickening of the skin with accentuation of normal skin markings
- Look at the distribution of the lesions over the body; observe their arrangement: isolated, clustered, linear, annular (in a ring). Ask if the lesions are itchy.
- Look for a possible cause: insect bites; scabies, lice, other parasitic skin infections; contact with plants, animals, jewellery, detergents, etc.
- Ask about any past or ongoing treatment: topical, oral or parenteral.
- Look for local or regional signs (secondary infection, lymphangitis, adenopathy, erysipelas) and/or systemic signs (fever, septicaemia, secondary focus).
- Consider the sanitary conditions of the family, particularly for contagious skin diseases (scabies, scalp ringworm, lice).
- Check tetanus vaccination status.
Patients with skin disease often present late. At this stage, primary lesions and specific signs may be masked by secondary infection. In these cases, it is necessary to re-examine the patient, after treating the secondary infection, in order to identify and treat the underlying skin disease.