Skin Cancer Classification

Skin cancers are named after the type of cells in the skin that are involved in the beginning of the cancer. The three most common types include:-

Basal cell skin cancer

This cancer begins in the basal cell layer of the skin. This is common in areas of skin exposed to the sun. The face is the most common place to find basal cell skin cancer.

In people with fair skin, basal cell skin cancer is the most common type of skin cancer. Basal cell skin cancer rarely spreads to other parts of the body. This is a slow-growing, locally invasive, malignant skin cancer affecting the epidermis.

Subtypes of basal cell cancer include:-

• Superficial – well deliniated
• Multifocal – more aggressive than other forms
• Morphoeic (scarring) – most invasive type of basal cell cancer
• Ulcerated
• Pigmented – similar in appearance as melanoma
• Cystic
• Nodular

Squamous cell cancer

This cancer originates in squamous cells. This is the commonest type of skin cancer seen in dark skinned individuals. It is usually found in places that are not exposed to the sun. In fair skinned individuals squamous cell skin cancer usually occurs on parts of the skin that have been in the sun, such as the head, face, ears, and neck.

Squamous cell skin cancer sometimes spreads to other parts of the body. The risk of spread is between 0.5 to 40% depending on the subtype.

Melanoma

These cancers begin in melanocytes or pigment/melanin producing cells. Melanoma can occur on any skin surface – both those areas exposed to the sun as well as those un-exposed. In men, it's often found on the skin on the head, on the neck, or shoulders and the hips. In women melanomas are commonly detected on the skin on the lower legs or on the shoulders and the hips.

This type of skin cancer is rare in people with dark skin. However, when found in dark skinned individuals, melanomas are detected under the finger or toe nails, on palms and soles.

Melanoma is more likely than other skin cancers to spread to other parts of the body. The cancer cells may be found in nearby lymph nodes and spread via lymphatic channels.

There are several subtypes of malignant melanoma. Superficial spreading melanoma, nodular melanoma and lentigo maligna melanomas make up 90% of all diagnosed malignant melanomas.

Other rarer types include Acral lentiginous melanoma, Acral amelanotic malignant melanoma etc.

Superficial spreading malignant melanoma is the most common type of melanoma seen on the trunk or legs and can appear as a new or existing mole. Nodular malignant melanoma appears blue or red and typically occurs as a new mole. Lentigo maligna melanoma is commonly seen on the face.