SKIN CANCER AND DERMATOLOGIC SURGERY
Melanoma is a cancer that develops from the pigment-containing cells known as melanocytes, normally in skin and mucous membranes. In 80% of cases it is a new lesion, while in 20% of cases it develops from a mole. The incidence of melanoma has remarkably increased in recent years, making up 75% of the total deaths caused by skin cancer. Globally, more than 50,000 people die from melanoma a year.
Who’s at risk?
- family history of melanoma (one or more cases);
- personal history of a previous melanoma;
- numerous naevi: people with 120 naevi are seven times more at risk to develop a melanoma than people with 15 naevi;
- multiple sun burns during childhood or adolescence;
- large congenital naevi.
Whilst it is not possible to prevent melanoma, it is possible to limit its primary cause, ultraviolet light (UV), from either the sun or from other sources (tanning beds), by using sunscreen.
Despite progress in chemotherapy and immunotherapy, when melanoma is diagnosed at an advanced stage, the survival rate is still very low. Prognosis depends on the cancer thickness when diagnosed. The thinner the lesion, with no invasion of deep skin layers (melanoma in situ), the higher the survival and healing rates. Early diagnosis is therefore crucial: if identified initially, melanoma can be readily cured, with a simple surgical procedure.
A mole screening consultation facilitates the early diagnosis of melanoma. It consists of a clinical and instrumental examination: family and personal medical history is retrieved, visual assessment of all moles (“mole mapping”) and dermatoscopy is performed.
Dermatoscopy is a non-invasive diagnostic technique, for the observation of skin lesions, allowing a better visualization of surface and subsurface structures. This diagnostic tool permits the recognition of morphologic structures, invisible to the naked eye.
A videodermatoscope is a digital instrument which consists of a high-resolution, colour fibreoptic video camera, incorporated into the final part of a probe. It permits the indirect visualisation of skin lesions on a monitor, with a 30-fold magnification. Dermatoscopy is performed by placing mineral oil on the skin lesion, that is subsequently inspected using the digital imaging system. A specific light source (polarised) enhances the visualisation of deep skin layers.
Images can be easily digitised, assessed and stored using a personal computer. Specialised software is used to create a database containing patients’ files and images.
During the follow-up screening, all previous and current images are compared and evaluated.
The assessment allows the detection of:
- naevi with irregularities: these are surgically excised and examined (histopathology);
- naevi without irregularities: these require a dermatoscopic follow-up at a 6-12 month interval, depending on the specific findings.
Dermatoscopy increases the accuracy of the early diagnosis of melanoma by 30%. It is a non-invasive, straightforward and repeatable diagnostic technique, with no contraindications.
When dermatoscopy was not so popular and widespread, the mole-check was based solely on the visual assessment of shape and evolution, the criteria expressed in the ABCDE rule: Asymmetry, Borders (irregular with edges and corners), Colour (variegated), Diameter (greater than 6 mm (0.24 inch), Evolving over time.
Observation of these clinical criteria only does not always result in an accurate screening, as it may lead to the excision of a large number of benign naevi, which appear irregular to the naked eye.
Dermatoscopy is also employed in the early diagnosis of pre-cancerous skin lesions (actinic keratosis) and non-melanocytic skin cancer (bcc, scc).
These malignant skin lesions usually have a lower risk of spreading, but they can invade and destroy tissues locally. Infiltration is particularly severe in certain areas, such as the eyelids, nasal region and lips. Early diagnosis allows surgical excision, with minimum scarring and quick recovery.
The option of meticulously monitoring skin lesions increases the likelihood of being able to postpone or avoid preventive surgery, especially if no clear sign of malignancy is observed. This is especially useful in patients who, for various reasons, are not strong candidates for surgery: patients with concomitant diseases, allergies, expectant mothers, skin lesions in visible areas (with major scarring and aesthetic burden). It is noteworthy that it is possible to monitor a large number of naevi and non-pigmented skin lesions.