Dermatology Glossary - Skin

Dermatology Glossary

·        Annular lesion - ring shaped

·        Erythema: dilation of blood vessels – colour goes away if pressed (blanching)

·        Macule: an alteration in colour (e.g. macular erythema)

·        Papule: a small lump, less than 0.5 cm in diameter

·        Nodule: lump bigger than 0.5 cm

·        Erythemato-squamous: red and scaly

·        Plaque: elevated (maybe only very slightly) area of skin > 2 cm.  Altered texture 

·        Vesicles and bullae = fluid within or beneath epidermis (blister). Vesicles < 0.5 cm, bullae > 0.5 cm. Can have both. E.g. vesicular-bullae eruption from a plant allergy

·        Pustule: accumulation of pus (can be just inflammatory not infectious, e.g. psoriasis)

·        Cellulitis: inflammation of deep dermis and subcutaneous tissue

·        Ulcer: loss of dermis and epidermis

·        Scale: at edge of inflammatory lesion, can be fine, large, dark, silvery (psoriasis)

·        Scar: fibrous tissue due to healing.  Atrophic scar is thin and wrinkled.  Hypertrophic scar is elevated

·        Poikiloderma: cutaneous pigmentation, atrophy and telangiectasia 

·        Comedo – pl. comedones: a plug of keratin and sebum in a dilated pilosebaceous orifice. Closed comedo = blackhead, open comedo = whitehead 

·        Cyst: any closed cavity with a membranous lining containing fluid

·        Petechiae – pl., petechiae: a haemorrhagic spot 1 – 2 mm diameter 

·        Purpura: haemorrhagic spot > 2 mm. Pressing down doesn‟t blanch – red cells are extravascular ® ?vessel damage. If purpura are palpable Þ vasculitis 

·        Ecchymoses: bruises – larger extravasations of blood

·        Telangiectases: permanently dilated small vessels

·        Guttate: a profusion of small macules or plaques

·        Serpinginous: a linear eruption which is S shaped or snake like (e.g. larva migrans – a worm)

·        Dermatitis: usually means eczema 

·        Structure of skin:

o   Epidermis:

§  Stratum corneum

§  Stratum lucidum

§  Stratum granulosum

§  Stratum spinosum

§  Stratum germanitivum (base of epidermis)

o   Dermis:

§  Papillary dermis

§  Reticular dermis

o   Subcutaneous tissue

·        Basic terms:  Non-specific reactive changes 

o   Hyperkeratosis: thickening of the stratum corneum. Eg due to trauma (eg the lump where you hold a pen) 

o   Parakeratosis: Nuclei are seen in the stratum corneum (would normally have died off, eg psoriasis)

o   Acanthosis: thickening of the epidermis, eg due to irritation