6. WHAT ARE THE TYPES OF MELANOMA?

There are four major types of cutaneous melanoma.  These melanomas are classified based on differences in their appearance and behaviour.

• Superficial spreading melanoma: This is the most common form of melanoma representing roughly 70% of all cases.  It undergoes a long radial growth phase prior to invading deeper into the skin, reaching the dermis, and posing a threat of distant spread via the blood stream or lymphatic system. Superficial spreading melanomas are typically characterised by a lesion with irregular borders and uneven pigmentation.
• Nodular melanoma:  This is most aggressive form of melanoma as it undergoes no radial growth phase and instead enters a vertical growth phase from the outset.  Nodular melanomas are typically characterised by a raised, nodular lesion with irregular patches of colour and an irregular border.  In rare cases this melanoma has no pigment altogether. 
• Acral lentiginous melanoma: This melanoma has a short horizontal growth phase. Therefore, it is considered more aggressive than superficial spreading melanoma and less aggressive than nodular melanoma.  This type of melanoma generally occurs in persons with darker skin and is commonly found on the soles of the feet, on the palms or under the finger nails.
• Lentigo maligna melanoma: Generally considered the least aggressive melanoma due to its long radial growth phase.  Lentigo maligna melanoma is commonly found on areas of the body that receive a lot of sun exposure such as the face, ears, neck and head.