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Basics of dermatology 

Basics of dermatology
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Subscriber: null; date: 16 October 2019

  1. Glossary [link]

  2. Chapter 1 Structure and function of the skin [link]

  3. Chapter 2 The dermatological consultation [link]

  4. Chapter 3 Dermatological treatments [link]

  5. Chapter 4 Patterns, shapes, and distribution in skin disease [link]

  6. Chapter 5 Endocrine dysfunction and the skin [link]

  7. Chapter 6 Failure to thrive and the skin [link]


Common descriptive dermatological terms:

  • Anetoderma – localized skin laxity causing either depressions or out pouching of the skin.

  • Anhidrosis – absence of sweating.

  • Alopecia – absence of hair in normally hairy site.

  • Anonychia – absence of nails.

  • Atrophy – loss of tissue from any layer of skin or subcutis.

  • Blister – fluid filled lesion.

    • Vesicle – small blister.

    • Bulla – large blister, may be unilocular or multilocular.

  • Comedo (pl. s) – (blackhead) plug of keratin or sebum distending the skin pore.

  • Closed comedo – (whitehead) plug of keratin or sebum within skin pore and covered by epithelium.

  • Crusting – dried serous exudate.

  • Dyschromatosis – altered, abnormal disolouration of the skin often with several shades of colour.

  • Ecchymosis – a bruise > 2mm in diameter.

  • Elastolysis – disintegration of the dermal elastin.

  • Enanthem – superficial mucosal lesions usually associated with infection.

  • Epidermis – the outer layer of the skin.

  • Erosion – superficial loss of epidermis (leaves no scarring).

  • Erythema – redness of the skin (may be difficult to assess in dark skin where it may manifest as increased pigmentation).

  • Erythroderma – erythema covering all or most of the body.

  • Escutcheon – hair growing upwards and outwards rather than downwards.

  • Exanthem – skin rash, usually associated with infection.

  • Excoriation – scratch mark causing loss of skin tissue.

  • Exfoliation – separation of outer keratin layer of skin in scales or sheets.

  • Fissure – splitting of the skin.

  • Follicular – associated with opening of hair follicle (skin pore).

  • Hypercornification – increase of the horny (cornified) layer.

  • Hyperhidrosis – increased sweating.

  • Hyperkeratosis – increased horny (cornified) layer.

  • Hyperplasia – excessive formation of cells.

  • Hypertrichosis – increased body hair in non-male pattern.

  • Hypohidrosis – decreased sweating.

  • Ichthyosis – dry skin, usually refers to inherited dry skin conditions.

  • Keratoderma – thickening of horny layer of skin.

  • Lichenification – exaggeration of the normal skin creases due to protective thickening of the epidermis (usually from chronic rubbing).

  • Macule – flat non-palpable area of change in skin colouration.

  • Maculopapular – rash consisting of macules and papules, e.g. measles.

  • Milium – a tiny keratin-filled cyst.

  • Monomorphic – all lesions are similar, e.g. molluscum contagiosum.

  • Morbilliform – measles-like i.e. widespread, blotchy red rash with tiny papules within.

  • Naevus – a ‘nest’ of cells of same morphological type.

  • Nodule – larger palpable lesion > 5mm size (approximately, varies in different textbooks).

  • Papule – small raised palpable lesion < 5mm size (approximately, varies in different textbooks).

  • Pathergy – lesions arising in sites of minor trauma seen particularly in Beçhet's disease and pyoderma gangrenosum.

  • Perifollicular – around margin of follicular opening.

  • Petechia (pl. iae) – tiny haemorrhagic dot (1–2mm).

  • Phlebolith – calcification within vein, hard and nodular.

  • Pica – compulsion to eat non-food items such as fabric, coal, wood etc.

  • Pityriasis – fine branny scaling.

  • Plaque – raised area of skin rash, usually greater than 2cm, e.g. psoriasis.

  • Poikiloderma – areas of skin showing mixture of altered pigmentation, telangiectasia and atrophy.

  • Polymorphic rash – several different types of lesions present, e.g. acne has papules, comedones (blackheads), pustules and cysts.

  • Pruritus – itching without a visible rash.

  • Pustule – small blister containing neutrophils (or other leukocytes).

  • Pyoderma – any purulent skin disease.

  • Rhagades – fissuring or splitting of the skin.

  • Scales – adherent keratinocyte (from stratum corneum).

  • Sclerosis – induration of subcutaneous tissue, which may include the epidermis.

  • Serpiginous – snake-like linear lesions.

  • Target lesion – three or more concentric rings of alternating pale and red skin, usually with central erythema or purpura.

  • Telangiectasia – small capillaries visible below skin.

  • Tinea – ringworm. Latin names used to designate body site affected e.g. for ringworm of scalp (T. capitis), hand (T. manuum), foot (T. pedis), body (T. corporis), groin (T. cruris), face (T. faciei), nails (T. unguium).

  • Ulcer – loss of epidermis and dermis (or deeper).

  • Ungual – pertaining to the nails.

    • Subungual – below nail.

    • Periungual – around nail.

  • Varioliform – lesions resembling smallpox.

  • Verrucous – rough, irregular surface resembling a viral wart.

  • Vesicle – see Blister.

  • Weal or wheal – raised area of pale oedema, transient and usually surrounded by red flare.

  • Xanthoma (pl. ta) – yellowish lipid-filled papules, nodules or plaques.

  • Xerosis – mildly dry skin often associated with eczema.