BENIGN CUTANEOUS TUMOURS:

Melanocytic naevi (moles)

Moles are a benign overgrowth of melanocytes that are common in white-skinned people. They appear in childhood and increase in number and size during adolescence and early adult life. They often start as flat brown macules with proliferation of melanocytes at the dermoepidermal junction (junctional naevi). The melanocytes continue to proliferate and grow down into the dermis (compound naevi), which causes an elevation of the mole above the skin surface. The pigmentation is usually even and the border regular. They eventually mature into a dermal naevus (cellular naevus) often with a loss of pigment.
Blue naevus is an acquired asymptomatic blue-looking mole. It is due to a proliferation of melanocytes deep in the mid-dermis.
Basal cell papilloma (seborrhoeic wart)

This is a common benign overgrowth of the basal cell layer of the epidermis. The lesion can be flesh coloured, brown or even black and often has a greasy appearance. The surface is irregular and warty and the lesions appear very superficial as though stuck on to the skin (Fig. 23.29). Tiny keratin cysts may be seen on the surface. They can be treated with cryotherapy or curettage.
Dermatofibroma (histiocytoma)
Dermatofibromas appear as firm, elevated pigmented nodules which may feel like a button in the skin. A peripheral ring of pigmentation is sometimes seen. They are often found on the leg and are commoner in females. There may be a preceding history of trauma or insect bite. The lesion consists of histiocytes, blood vessels and varying degrees of fibrosis. If symptomatic, excision is required.
Epidermoid cyst (previously 'sebaceous cyst')
Epidermoid cysts present as cystic swellings of the skin with a central punctum. They contain 'cheesy' keratin rather than sebum; thus the old term 'sebaceous cyst' should be avoided. These cysts occasionally rupture causing significant dermal inflammation which is not infected.
Pilar cyst (trichilemmal cyst)
Pilar cysts are smooth cysts without a punctum, usually found on the scalp. They may be multiple and familial.
Keratoacanthoma
Keratoacanthomas are rapidly growing epidermal tumours which develop central necrosis and ulceration (Fig. 23.30). They occur on sun-exposed skin in later life and can grow up to 2-3 cm across. Whilst they may resolve spontaneously over a few months, they are best excised, both to exclude a squamous cell carcinoma (which they can mimic) and to improve the cosmetic outcome.
Pyogenic granuloma (granuloma telangiectaticum)
Pyogenic granulomas are a benign overgrowth of blood vessels. They present as rapidly growing pinkish red nodules which are friable and readily bleed. They may follow trauma and are often found on the fingers and lips. They are best excised to exclude an amelanotic malignant melanoma.

Cherry angioma (Campbell de Morgan spots)
They are benign angiokeratomas that appear as tiny pinpoint red papules, especially on the trunk, and increase with age. No treatment is required.