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Atypical (dysplastic) naevus To be ‘atypical naevi’, lesions must have three of the following in situ characteristics: variegated pigmentation; ill-defined borders; undulating irregular surfaces; or size >5 /uni00A0 mm. Terminology is confused because, although...

Basal cell carcinoma This is usually a slow-growing, locally invasive, malignant tumour of pluripotential epithelial cells arising from basal epidermis and hair follicles; hence, it a ff ects the pilosebaceous skin. Summary box 45.2 Basal cell carcinoma /uni25...

Blood supply of the skin The body can be envisaged as three-dimensional segments of tissue called angiosomes, each with an arterial supply and a venous drainage. Blood equilibrates and flows between neighbouring angiosomes via ‘choke’ vessels, which tend to be...

Common vascular birthmarks Salmon patch A salmon patch is a vascular malformation that presents as a pinkish macule, usually at the nape of neck ( Figure 45.42 is caused by an area of persistent fetal dermal circulation that usually disappears at 1 year. Cap...

Congenital/genetic disorders Neurofibromatosis There are two distinct neurofibromatosis (NF) syndromes, in which Schwann cells form tumours ( Figure 45.3 ). Each is caused by di ff erent genes on di ff erent chromosomes: 70% are autosomal dominant and 30% arise fr...

Cutaneous manifestations of generalised disease Many diseases have cutaneous manifestations that present in surgical practice. These include: necrobiosis lipoidica, granu loma annulare in diabetes mellitus and pyoderma gangreno sum in inflammatory bowel disease...

Cutaneous squamous cell carcinoma SCC is a malignant tumour of keratinising cells of the epider - mis or its appendages. It arises from the stratum basalis of the epidermis and expresses cytokeratins 1 and 10. Epidemiology Four BCCs occur for every SCC, whi...

Cylindroma (turban tumour) A variant of eccrine spiradenoma that coalesce when multiple on the scalp, forming a ‘turban tumour’. Cylindroma (turban tumour) A variant of eccrine spiradenoma that coalesce when multiple on the scalp, forming a ‘turban tumour’. ...

Dermis The dermis constitutes 95% of the skin and is structurally divided into a superficial papillary layer, which is composed of delicate collagen and elastin fibres in ground substance, into which a capillary and lymphatic network ramifies, and a deeper retic...

Eccrine poroma (papillary syringoma) These are single raised or pedicled lesions found most often on the palm or sole. Eccrine poroma (papillary syringoma) These are single raised or pedicled lesions found most often on the palm or sole. Eccrine poroma (papill...

Epidermis The epidermis constitutes 5% of the skin and is composed of five layers of keratinised, stratified squamous epithelium – the strata: basalis (deep), spinosum, granulosum, lucidum and corneum (superficial). Most epidermal cells are keratinocytes arrang...

FUNCTION OF THE SKIN Skin and subcutaneous tissue have several important functions: /uni25CF Barrier to the environment enveloping the body and pro tecting against trauma, radiation and pathogens. Secreted sebum and sweat mix to form a microscopic acidic film a...

FUNCTIONAL ANATOMY AND PHYSIOLOGY OF SKIN Skin can be divided into two layers: the outer epidermis and the inner dermis. Deep to the dermis lies subcutaneous fat and any remnants of the panniculus carnosus. FUNCTIONAL ANATOMY AND PHYSIOLOGY OF SKIN Skin can b...

FURTHER READING Calonje JE, Brenn T , Lazar A, Billings S. McKee’s pathology of the skin , 5th edn. Amsterdam: Elsevier, 2019. Soyer HP , Argenziano G, Ho ff mann-Wellenhof R, Zalaudek I. Dermos - copy: the essentials , 3rd edn. Philadelphia, PA: Mosby Wolfe, 2...

Giant congenital pigmented naevus or giant hairy naevus This hamartoma of naevo-melanocytes causes confusion because its definition and management are contentious. It has a similar histology to compound naevi, but with naevus cells distributed variably througho...

Giant congenital pigmented naevus or giant hairy naevus This hamartoma of naevo-melanocytes causes confusion because its definition and management are contentious. It has a similar histology to compound naevi, but with naevus cells distributed variably througho...

Hair follicles Trichoepithelioma These are small skin-coloured nodules found most often in the nasolabial folds. Trichoepithelioma is clinically and histologi - cally similar to a BCC. Hair follicles Trichoepithelioma These are small skin-coloured nodules foun...

Infections Skin and soft-tissue infections can be localised or spreading, necrotising or non-necrotising. Localised or spreading non-necrotising infections usually respond to broad-spectrum antibiotics. Localised necrotising infections need surgical debridemen...