There are a number of different types of melanoma and your pathology report will describe your melanoma classification.
Superficial Spreading Melanoma
This is the most common form of melanoma representing roughly 70% of all cases. This type of melanoma 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 bloodstream or lymphatic system.
Superficial spreading melanomas are typically characterised by a lesion with irregular borders and uneven pigmentation.
This is the most aggressive form of melanoma and represents between 10-15%. 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. Some nodular melanomas have no pigment and this can make diagnosis more difficult.
Lentigo Maligna Melanoma
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 type of melanoma represents 5-10% of all melanomas.
Acral Lentiginous Melanoma
This melanoma has a short horizontal growth phase. It is typically 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 those with darker skin.This type of melanoma represents less than 5% of all melanomas.
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)
Intransit metastases are melanoma deposits within the lymphatic vessels located close to the site of the primary melanoma. Up to 10% of melanoma patients develop intransit metastases between the primary tumour site and draining regional lymph nodes.
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.