Premalignant
lesions
Actinic keratoses (senile keratoses, solar keratoses) are areas of
epidermal dysplasia giving rise to cutaneous scaling, usually observed in
sun-exposed fair skin. These lesions are potentially malignant. Superficial
lesions are best removed by rapid and even freezing with carbon dioxide or
liquid nitrogen on a cotton wool bud. Diathermy preceded by curettage of horny
lesions is equally effective, but more likely to leave superficial scarring.
Indurated lesions are best excised. Multiple lesions may clear with topical
5-fluorouracil cream. An effective sunscreen is important as improvement follows
avoidance of sunlight, which is also important prophylactically. Radiotherapy
should not be used for solar keratoses.
Bowen’s
disease
Bowen’s disease is an intraepidermal squamous cell carcinoma that is
potentially malignant and appears as a persistent, progressive, usually flat,
red, scaly or crusted plaque (Fig. 13.32). It is more frequently seen in the
elderly. It is triggered mainly by solar radiation, but if those keratoses with
Bowen’s features are separated off, the cause most frequently found is arsenic
ingestion. Most patients are
Erythroplasia
of Querat
Erythroplasia of Querat describes Bowen’s of the glans penis. It
occurs most commonly in uncircumcised males.
Radiodermatitis
This is an area of skin damaged by excessive exposure to Xirradiation.
Early erythema occurs which goes on to desquamation and pigmentation. If the
dose is very great ulceration may occur. Later atrophy, irregular
hyperpigmentation, telangiectasia and hair loss occur. Eventually, squamous cell
carcinoma may develop.
Chronic
scars
A carcinoma which develops in a scar (Marjolin’s ulcer) (Fig.
13.33)
presents the following characteristics. It grows slowly, as the scar is
relatively avascular. It is painless, as scar tissue contains no nerves.
Secondary deposits do not occur in the regional lymph nodes as lymphatic vessels
have been destroyed. If the ulcer invades normal tissue surrounding the scar, it
extends at a normal rate, and lymph nodes are then liable to be involved.
Sebaceous
epidermal naevus
Sebaceous epidermal naevus (of Jadassohn, organoid naevus) (Fig.
13.34)
is a common condition, frequently affecting the scalp. It initially appears as a
raised papular yellow area, developing into a papillomatous area as the child
Porokeratosis (of Mibelli) is characterised by annular plaques with
horny borders. About 13 per cent may transform into basal cell or squamous cell
carcinomas.