DERMATOLOGIC LESIONS
Introduction
Dermatologic diagnosis is based up on systematic approach which includes history, physical examination and diagnostic tests.
There are some relevant aspects that must be asked in the history:
- Age.
- Breed.
- Sex.
- Occupation (work environment).
- Geographic location.
- Previous skin diseases.
- Associated symptoms (itching, pain, etc.).
- Therapy used and response.
- Exacerbation of the lesions by the sun or irritating substances exposure.
- Similar cases in family.
In the physical examination, the appearance of the lesion is an important feature to be considered, that is why a necessary careful approach and detailed examination must proceed as follows:
Dermatology classifies lesions primarily by their visual appearance and texture. Lesions are divided into two general categories, primary and secondary. Primary lesions are those that are directly associated with the disease process and usually appear early in the course of the disease. Those appearing later are called secondary lesions and may be a result of the ongoing disease process and changes to the primary lesions.
A morphological classification of dermatological lesions is most helpful to the identification of the diseases present.2
Primary lesions | Secondary lesions |
|---|---|
• Macules | • Scale |
• Papules | • Crust |
• Plaque | • Fissure |
• Nodules | • Scar |
• Vesicles | • Excoriation |
• Bulla | • Lichenification |
• Wheals | • Erosion |
• Pustules | • Atrophy |
• Cysts | • Ulcer |
• Purpura | |
• Petechiae | |
• Ecchymoses | |
• Telangiectasia |
Primary lesions
Macule: Well-circumscribed, flat lesions that are noticeable because of their change from normal skin color. They may be red due to the presence of vascular lesions or due to inflammation, or pigmented due to the presence of melanin, hemosiderin, and drugs.
E.g.
- Ephelis or freckle
- Vitiligo
- Tinea versicolor.
Papule: Elevated, solid and circumscribed lesion, usually 1 cm or less in diameter.
E.g.
- Hyperkeratotic: Warts, seborrheic keratoses
- Purple: Drug eruptions, Kaposi's sarcoma
- Red: Erythema multiforme, scabies.
Plaque: Elevated, flat-topped, firm and superficial lesion, usually greater than 1 cm in diameter; may be coalesced papules.
E.g.
- Psoriasis
Wheal: Transient, solid, itchy, raised area of cutaneous edema with irregular shape, different diameter and variable blanching and erythema.
E.g.
- Urticaria
- Insect bites.
Nodule: Solid raised, circumscribed, firm lesion; variable diameter (usually 1–3 cm); deeper in dermis than papule. It can be seen in gross inspection or only on palpation.
E.g.
- Lipoma
- Erythema nodosum.
Vesicle: Elevated, thin-walled lesion, filled with serous (clear) fluid, less than 1 cm in diameter.
E.g.
- Herpes simplex
- Varicella-Herpes zoster
- Dermatitis herpetiformis.
Bulla: Elevated lesion filled with clear fluid, greater than 1 cm in diameter.
E.g.
- Pemphigus
- Pemphigoid
- Drug eruptions
- Stevens-Johnson syndrome
- Blister.
Cyst: Elevated and encapsulated lesion filled with semisolid, liquid or gaseous content.
E.g.
- Sebaceous cyst
Pustule: Elevated lesion filled with purulent fluid. The presence of the pustule does not necessarily signify the existence of an infection.
E.g.
- Acne vulgaris
- Impetigo
- Variola
- Folliculitis
- Candidiasis.
Secondary skin lesions
Scale: Flaky exfoliation, a plate-like excrescence of varied size, usually composed of accumulated stratum corneum.
E.g.
- Psoriasis
- Dermatitis
- Tinea versicolor
- Pityriasis rosea.
Crust (scab): A solid consolidation of dried serum, blood, pus.
E.g.
- Eczema
- Scab on abrasion.
Lichenification: Thickened and rough epidermis with accentuation of skin markings.
E.g.
Scar: Fibrous tissue secondary to dermis injury. It may be pink, red or white; atrophic or hypertrophic (keloid).
E.g.
- Healed wound.
Excoriation: Loss of epidermis caused by a traumatic lesion causing a linear area.
E.g.
- Deep scratch
- Abrasion.
Fissure: A linear and small split or crack in the epidermis and dermis.
E.g.
- Cheilosis.
Erosion: Discontinuity of the skin with loss of part or all epidermis, usually follows rupture of vesicle or bulla.
E.g.
- Varicella (following rupture)
- Variola (following rupture).
Ulceration: Discontinuity of the skin with loss of epidermis; and sometimes hipodermis. Usually heals with scaring.
E.g.
- Decubitus
- Herpes simplex
Ulcers: Ulceration without tendency of healing (scaring).
E.g.
- Stasis ulcers.
Atrophy: Reduction of skin thickening ocurring at any skin layer.
E.g.
- Striae
- Aged skin.
Vascular Lesions
Purpura: Red-purple nonblanching colored lesion due to extravation of blood into the tissue.
E.g.
- Henoch-Schönlein purpura
- Thrombocytopenic purpura
- Infection.
Petechiae: It is a punctiform purpura.
E.g.
- Vasculitis
- Infection.
Ecchymoses: Purpura greater than 1 cm in diameter.
E.g.
- Trauma
Telangiectasia: Permanent dilated superficial blood vessels.
E.g.
- Telangiectasia in liver disease
- Telangiectasia in pregnancy
- Telangiectasia in breast cancer
- Telangiectasia in lupus erythematosus, systemic or discoid.
CLASSIFICATION OF SKIN DISEASES
Dermatologic lesions may be classified as immune mediated diseases, vesiculobullous diseases, and diseases that are genetically transmitted.
Andrews and Regezi classification
- Congenital ectodermal defects
- Hypohidrotic ectodermal dysplasia(Anhidrotic ectodermal dysplasia)
- Hidrotic ectodermal dysplasia(Clouston syndrome)
- Immune-mediated diseases (Papules and plaques)
- Lichen planus
- Linear lichen planus (Zosteriform lichen planus)
- Annular lichen planus
- Hypertrophic lichen planus (Lichen planus verrucosus)
- Ulcerative lichen planus
- Bullous lichen planus
- Follicular lichen planus
- Drug-induced lichen planus
- Reiter's syndrome
- Graft versus host disease
- Systemic sclerosis
- CREST syndrome
- Papulosquamous dermatoses
- Psoriasis
- Pityriasis rosea.
- Chronic blistering dermatoses
- Pemphigus (Vesicles bulla/pustules)
- Pemphigus vegetans
- Pemphigus foliaceus
- Brazilian pemphigus
- Pemphigus erythematosus
- Paraneoplastic pemphigus
- Cicatricial pemphigoid
- Epidermolysis bullosa acquisita
- Dermatitis herpetiformis.
- Vesicles/bullae/pustulesErythema and Urticaria
- Erythema multiforme
- Erythema migrans
- Drug-induced bullous erythema multiforme(Stevens-Johnsons syndrome)Toxic epidermal necrolysisAnnular urticarial reactions
- Endocrine diseases
- Acanthosis nigricans
- Connective tissue diseases
- Lupus erythematosus(Systemic + discoid) lupus erythematosus
- Some genodermatosis and acquired syndromes
- Epidermolysis bullosa
- Pachyonychia congenita
- Darier's disease
- Hailey-Hailey disease
- Incontinentia pigmenti
- Dyskeratosis congenita
- Porokeratosis.(Plaque type porokeratosis Mibelli)
- Epidermal nevi
- White sponge nevus
- Dermatoses resulting from physical factors
- Solar elastosis
- Abnormalities of dermal connective tissue
- Ehlers-Danlos syndrome.