MALIGNANT MELANOMA
Malignant melanoma is a malignant tumor that arises from cutaneous melanocytes. It is an increasingly common tumor. Melanoma often has a slow early growth rate during which curable lesions may be detected and removed. Most melanoma probably arise de-novo but some arise from pre-existing moles.
The different types of melanoma are:
- Superficial spreading melanoma
- Nodular melanoma - pigmented nodule with no preceding in situ phase.
- Lentigo maligna melanoma (affects sun-damaged skin of the head and neck) - An irregularly pigmented, irregularly shaped macule (a lentigo maligna)
- Acral-lentiginous melanoma (soles of feet, palms of hands or under the nails - the subungual melanoma).
Melanomas can also described by their colour, site and degree of spread:
- Totally amelanotic melanomas are rare and occur especially on the soles of the feet. Flecks of pigment can usually be seen with a lens.
- Subungual melanomas are painless areas of pigmentation expanding under the nail and onto the nail fold.
- Metastatic melanoma has spread to surrounding skin, regional lymph nodes or to other organs. At this stage it can rarely be cured.
The ABCD rule - used by health professionals and patients to check for the main warning signs of melanoma:
- A = Asymmetry - The two halves of the mole look different in shape and/or colour
- B = Border - Look around the edge of the mole. Melanoma will often have an irregular, jagged, notched or blurred border
- C = Colour - Several different colors or shades of colour, or a single colour that is different to other moles
- D = Dimensions (changing size) - Melanoma can spread outwards as a flat lesion, it can grow upwards as a hard lump and some do both.
Etiology:
- UV exposure
- Genetics and age (15-34 age group)
- Pre-existing melanocytic naevi
Clinical findings – malignant melanoma has the following characteristics:
- Asymmetric
- Irregular border
- Three or more colors. Any new or old and changing mole that has two or more colors with an uneven distribution of pigment.
- Persistent growth - even if they are symmetrical in shape and colour
- Bleeding moles without a history of trauma
- Nodules and plaques - any new solitary nodule or plaque where a benign diagnosis (dermatofibroma) cannot be made with confidence. 50% of nodular melanomas are hypo/amelanotic and so may present as a red-pink elevated lesion
- A new pigmented line in a nail or unexplained destruction of a nail.
Staging of melanoma – TNM classification