Complex Skin Cancers

Overview

Skin cancers are extremely common in Australia, due to a combination of the very high levels of ultraviolet radiation and a large proportion of the population having light coloured skin. As such, many skin cancers occur in highly visible areas of the body and therefore need careful management to minimise the functional and aesthetic impact of treatment without compromising on the success of curing the cancer.

Types of Skin Cancer

Listed in order of how commonly they occur

• Basal cell carcinoma (BCC)

• These very common cancers very rarely spread to other sites but are locally destructive if left untreated. Many subtypes exist, which can affect the management options. Commonly encountered subtypes include:

  • Usually easily treated:

    • Superficial - often treated successfully with creams eg imiquimod (Aldara) or 5-fluorouracil (Efudix)

    • Nodular - usually appear with a round ‘pearly’ edge and a network of very fine blood vessels similar to the roots of a tree. These lesions are usually easily spotted and can be treated with surgical removal.

  • Often difficult to treat:

    • Morphoeic/Sclerosing - these often occur in the central facial region and have a waxy/scar like appearance. They usually have poorly defined edges and may have extensive subclinical extension, that may include invasion of nearby nerves. As a result of their relatively indolent appearance, these lesions often go undetected for a while, resulting in more extensive disease.

    • Micronodular - these lesions form multiple small nodules of tumour. Similarly to morpheic BCCs, they may not distort the overlying skin and therefore can have considerable subclinical extension yet go unnoticed for a while.

    • Infiltrative - these aggressive lesions form fine cords of tumour that may not distort the overlying skin and therefore can have considerable subclinical extension, particularly including invasion of nearby nerves and other adjacent structures.

    • Basosquamous - these lesions are a mixture of both BCC and SCC cells, but more closely resemble BCCs in terms of prognosis and appearance under the microscope.

• Squamous cell carcinoma (SCC)

• These common cancers range from small skin horns to big ulcers. Depending on the site, size, how abnormal the cells are (differentiated) and whether they invade nerves or blood/lymphatic vessels these can be more or less likely to spread to other sites (metastasise).

• Melanoma

  • Melanoma in-situ (MIS) is pre-invasive disease ie it is confined to the very thin waterproofing layer of the skin (epidermis). Therefore MIS can be cured if surgically removed before it invades the underlying dermis of the skin. MIS can be either an isolated lesion when it may simply be termed ‘melanoma in situ’ or occur in the presence of significant sun damage, when it is termed ‘lentigo maligna’.

    • Lentigo maligna can be difficult to determine the extent of clinically, often covering a large area of skin. However, a relatively new technology termed ‘in vivo confocal microscopy’ can be employed pre-operatively to help visualise the borders of the lesion. This increases the likelihood of complete surgical removal at the first attempt without removing excessive amounts of uninvolved skin. Since many of these lesions occur on the face, this is of paramount importance.

  • Invasive melanoma occurs when the cancerous melanocytes invade the deeper part of the skin (dermis) beneath, which contains blood and lymphatic vessels. Once cancer cells are in the dermis, they can easily then invade those vessels and spread to other parts of the body such as the lymph nodes or critical structures such as the liver or lungs. Important subtypes of melanoma include:

    • superficial spreading

    • nodular

    • lentigo maligna melanoma

    • desmoplastic

    • acral

  • Sentinel Lymph Node Biopsy

    • The most common route of spread for a melanoma is by the lymphatic system to the regional lymph nodes.

    • The directly draining lymph nodes are known as ‘sentinel nodes’ and are the most likely places that a melanoma will first spread to. Consequently, performing an excision biopsy of any such sentinel nodes serves both as a staging tool and to reduce the likelihood of regional recurrence.

    • Determining a melanoma patient’s risk that the disease has spread to the sentinel nodes can be done using a personalised risk prediction tool that A/Prof Varey led the development of.