diagnostic approach

common dermatological problems fall into one of seven categories 

Common dermatological conditions: 

AcnePsoriasisAtopic dermatitis (eczema)UrticariaSun-related skin cancerDrug-related eruptionsInfections Bacterial: – impetigo Viral: – warts– herpes simplex, herpes zoster– pityriasis rosea– exanthemata Fungal: – tinea– candidiasis– pityriasis versicolor Acute and chronicPapular: – pediculosis– scabies– insect bites

A problem that does not fit into one of these seven groups is either an unusual condition or an unusual presentation of a common condition and probably merits a consultant’s opinion.

Glossary of terms:

• Acral Hands and feet
• Intertriginous In areas of skinfolds
• Seborrhoeic Yellow-brown and waxy
• Annular Ring-like
• Circinate Circular
• Arcuate Curved
• Reticulate Net-like
• Pityriasis (pityron = bran)Fine, bran-like scaly desquamation or powdery
• Guttate ‘Dew drop’
• Rosea Rose-coloured
• Morbilliform Like measles
• Morphoea Circumscribed scleroderma or skin infiltrate
• Livido Cyanotic discolouration
• Lichen Any papular skin disorder resembling lichens
• Verrucous Rough and warty

History

The three basic questions are: 

1. Where is the rash and where did it start?
2. Is the rash itchy? – mild moderate severe(wakes up at night with marked excoriation of the skin)
3. How long has the rash been present?

Acute (hours–days)	Urticaria
	Atopic dermatitis
	Allergic contact dermatitis
	Insect bites
	Drugs
	Herpes simplex/zoster
	Viral exanthemata
Acute → chronic (days–weeks)	Atopic dermatitis
	Impetigo
	Scabies
	Pediculosis
	Drugs
	Pityriasis rosea
	Psoriasis
	Tinea
	Candida
Chronic (weeks–months)	Psoriasis
	Atopic dermatitis
	Tinea
	Pityriasis versicolor
	Warts
	Cancers
	Skin infiltrations (such as granulomata, xanthomata)

1. Could this be a drug rash?
2. Has this rash been modified by treatment?
3. Do any contacts have a similar rash?

• Do you have contact with a person with a similar eruption?
• What medicines are you taking or have you taken recently?
• Have you been exposed to anything different recently?
• Do you have a past history of a similar rash or eczema or an allergic tendency (e.g. asthma)?
• Is there a family history of skin problems?
• Relieving or aggravating factors

Examination

• dermis alone or the epidermis as well ?
  • epidermis : scaling, crusting, weeping, vesiculation or a combination of these 
  • dermis alone is involved: the lesion is by definition a lump, a papule or a nodule

Epidermal	Atopic dermatitis
	Psoriasis
	Tinea
	Pityriasis rosea
	Impetigo, herpes, warts
	Cancers
	Scabies
	Solar keratoses
Dermal	Urticaria
	Insect bites, pediculosis, scabies
	Drugs
	Skin infiltrations
	Viral exanthemata

• feature of an eruption
• Disease does not affect the skin in isolation and it is unforgivable to look only at the skin and ignore the patient as a whole. In every case examine the mouth, scalp, nails, hands and feet.
• colour, the shape and the size.
• DISTRIBUTION OF THE LESIONS
  • widespread: distributed centrally, peripherally, or both
  • in a specific area

Face	Rosacea
	Impetigo
	Psoriasis
	Atopic dermatitis
	Photosensitive (e.g. drugs)
	Herpes simplex
	Acne vulgaris
	Cancers
	Viral exanthemata
Scalp	Psoriasis
	Seborrhoeic dermatitis
	Pediculosis
	Tinea
	Atopic dermatitis
	Folliculitis
Flexures	Atopic dermatitis
	Psoriasis
	Seborrhoeic dermatitis
	Tinea
	Candida
	Pediculosis
Mouth	Aphthous ulcers
	Herpes simplex
	Candida
	Measles
Nails	Psoriasis
	Tinea
	Dermatitis
Penis	Scabies
	Genital herpes and warts
	Candida
	Psoriasis

Typical sites on the face affected by the skin conditions indicated