Skin cancer

From Ganfyd

Skin cancer is divided first into Melanoma and other skin cancers. The latter are distinct from each other but melanoma remains the outstandingly lethal one and a different task for prevention and design of processes for treatment. Metastatic cancers from other organs may appear in the skin - for unclear reasons breast cancer shows some predeliction for the area beneath the eye.

Melanoma

Cancer of melanocytes, the pigment cells in the skin and retina.

Initiation appears to be related to or commonly by exposure to sun - ultra-violet.

Examine pigmented lesions considering:- A - Asymmetry - in one or both axes of the visible plane is bad. B - Borders - smooth, definite and calm ones are best C - Colour - uniform colour is best, spots of jet black worst D - Diameter - smaller than 7mm is much less worrying

Treatment of melanoma

See main article melanoma treatment

Melanomas are typically very resistant to radiation, chemotherapy and often have micro-metastases prior to presentation. Recent advances in immunotherapy seem promising.

Non-Melanoma Skin Cancer

Basal Cell Carcinoma (Rodent Ulcer)

The BCC developes slowly, usually as a pearly nodule or small ulcer. It is said not to metastasise, but may become immensely destructive by local extension. It occurs most commonly in areas exposed to the sun, thus above a line from chin to ear, but catches us out by appearing anywhere, occasionally, including where the sun almost certainly has never shone. Classically it is differentiated from other skin lesions by a pearly rolled edge which becomes more pronounced when the lesion is stretched by pulling the skin.

Local excision as with an SCC is the usual treatment. Recurrence (of new primaries) is common. They are predominately found in the elderly who have a life time of sun exposure, and therefore considerable damage is often done to all sun exposed sites.

Squamous Cell Carcinoma (SCC)

Again this develops in areas of chronic sun exposure but may also be associated with other carcinogens such as tar or arsenic (eg smoker's fingers). In rare cases it may arise at the edge of chronic skin ulcers (Marjolin's ulcer). There appears to be an increased risk with radiotherapy. It may, but rarely does, metastasise.

On clinical examination the typical appearance is of an ulcerated lesion. The edge is raised and everted and the colour is red-brown. The keratoacanthoma, although commmonly considered a benign lesion may be a low grade form of SCC.

Histology demonstrates disordered keratinocytes, typical malignant cytology and foci of keratinisation.

Treatment is generally by local excision (by various techniques). Depending on the size and site, operator and contractual arrangements for funding this may be done in General Practice, by a Dermatologist, or by a Plastic Surgeon. If in doubt, escalate. Biopsying an SCC is permissible. Surveillance after excision should follow for some years of the area, and adjacent areas and similar areas of skin. Some of this should be done by healthcare professionals.

Basi-squamous cancers

Sometimes it isn't just the appearance that is hard to classify as SCC or BCC...

Bowen's Disease (carcinoma in situ of the Skin

SCCs develope slowly, and a period (typically of years, perhaps many years) of Solar keratosis becoming increasingly odd and morphing into the appearance of definite Bowen's Disease preceeds overt SCC. The earlier the process is recognised the less severe the treatment required to interrupt it, and the less risk of progression and metastasis. Not all solar keratoses (synonym: Actinic keratoses) progress, and some revert spontaneously. Classically these present as slow groing non healing lesions with a slightly crusty surface.

Keratoacanthoma

Classically described as getting better about the time the nerve of those observing them fails and leads to excision, but in fact sufficient of them become or are SCCs to indicate that excision may be better than watchful waiting. Histologically they are hard or impossible to distinguish from SCC, and it is the history and macroscopic organisation of the tumour which is diagnostic.

The keratoacanthoma arises as a small nodule, grows rapidly and develops a central crater full of keratin, a plug which may be expelled this being taken a a sign that involution is imminent. Left alone it regresses leaving a scar.