Risk Factors for Skin Cancer
UV light exposure
Clinical Pearls of Skin Malignancies
More common with advancing age
Lesions often single (but not always)
Lesions usually asymmetrical
Inflammation may or may not be present
Premalignant lesions may or may not be present
Growth rate is variable, BUT generally has evolved over months gradually
Any lesion satisfying the above, and for which a non-malignant diagnosis is not immediately evident, YOU MUST BIOPSY
Cutaneous Neoplasms and Cell of Origin
Squamous cell carcinoma - keratinocytes of the spinous layer
LC Histiocytosis - Langerhans cells
Bascal cell carcinoma - Basal keratinocytes
Melanoma - Melanocytes
Basal Cell Carcinoma (BCC)
Most common malignancy in humans
Related to UV light exposure
Does not metastasize... Direct spread
Central ulcer is often present
Basal Cell Carcinoma - Key Features
Central ulcer is common
Squamous Cell Carcinoma (SCC)
Come from the precancerous lesion: actinic keratosis
Low risk of metastasis (about 5% over 2 years), except on the lips or ears or in the context of immunosuppression or in areas of scarring.
If they metastasize, the outcome is terrible.
Can develop into SCC
Bowen's Disease: SCC in Situ
Restricted to the epidermis
Cancer arising from melanocytes.
Early detection is an important goal in cutaneous melanoma management.
Tumour depth is the most important prognostic factor for cutaneous melanoma.
Melanoma that has spread often has a very poor prognosis.
Growth of Melanoma
First starts in a radial growth phase where the lesion gets bigger and grows outwards.
Next comes the vertical growth phase where it expands deep into the tissue. This is BAD. Ideally, you want to catch and excise the menaloma before this point.
If it has less than 1mm depth, there is a 95% chance of survival. If however, it is deepr than 4mm, there is less than a 20% chance of survival.
The leeching of pigment onto skin around the nail. This is highly suggestive of melanoma.
Stage I is less than 1mm thickness and has >95% chance of survival
Stage II has >2mm thickness and has about a 70% chance of survival
Stage III has nodal involvement, but no metastasis and is about 45% chance of survival
Stage IV has distant metastasis and has less than a 10% chance of survival