This is the most common form of melanoma representing roughly 70% of all cases. This type of melanoma undergoes a (superficial) growth phase called radial growth prior to invading deeper into the skin, reaching the dermis, and posing a threat of distant spread via the bloodstream or lymphatic system. They can develop a vertical growth phase over time.
Superficial spreading melanomas are typically characterised by having irregular borders and uneven pigmentation.
This is the most aggressive form of melanoma as it has a vertical growth phase from the outset. Nodular melanomas are typically characterised by being a raised, nodular lesion with irregular patches of colour and an irregular border. Up to 20% of these nodular melanomas may not have any igment and this can make diagnosis more difficult.
Generally considered the least aggressive melanoma due to its long radial growth phase. Lentigo maligna melanoma is commonly found on older people who have worked in an outdoor occupation. These occur on areas of the body that have received a lot of sun exposure and are therefore most common on the face, ears, neck and head.
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 is found on the soles of the feet, on the palms or under the fingernails. It is the most common form of melanoma in Asians and dark skinned people.
Ocular melanoma is melanoma found in the eye, and is relatively uncommon, accounting for only 3% of all melanoma cases. It begins when melanocytes in the eye grow uncontrollably. There are two types of melanoma that occur in the eye; uveal (choroid, iris and ciliary body) and conjunctival (which occurs in the filmy white covering of the eye).
Other less common types of melanoma include desmoplastic, polyploid and naevoid. Mucosal melanomas can be found in tissues in the respiratory, digestive and reproductive tracts. 5-10% of melanomas are initially found in internal areas of the body such as lymph nodes or organs without any obvious signs on the skin.