Patient Resources //
About Skin Cancer:
What is nodular melanoma? (DermNetNZ)
Nodular melanoma is an invasive form of melanoma. Melanoma is a potentially serious skin cancer that arises from pigment cells (melanocytes).
According to New Zealand Cancer Registry data, 2256 invasive melanomas were diagnosed in 2008 and at least 15% were reported as nodular melanoma. There were 371 deaths from all types of melanoma in 2008 (69% were male) and about half of these were nodular melanomas.
In nodular melanoma, malignant melanoma cells proliferate downwards through the skin – this is known as vertical growth. The lesion presents as a nodule (lump) that has been rapidly enlarging over the previous weeks to months. It can arise de novo in normal-appearing skin, or within an existing melanoma of other type.
A nodular melanoma can penetrate deeply within the skin within a few months of its first appearance.
Who gets nodular melanoma?
Nodular melanoma accounts for about 15% of melanoma in Australia and New Zealand. Although more common in very fair skin (skin phototype 1 and 2), it may also occur in those who tan quite easily (phototype 3), and occasionally in brown or black skin (phototype 4-6).
Nodular melanoma is more common in males than females. Most are over the age of 50 when it is diagnosed.
The main risk factors for nodular melanoma are:
Previous invasive melanoma or melanoma in situ
Many melanocytic naevi (moles)
Multiple (>5) atypical naevi (funny-looking moles)
Fair skin that burns easily
It is less strongly associated with sun exposure than superficial spreading and lentigo maligna types of melanoma.
What does nodular melanoma look like?
Nodular melanoma may arise on any site, but is most common on exposed areas of the head and neck.
Nodular melanoma presents as a rapidly enlarging lump (over several weeks to months). The characteristics of nodular melanoma include:
Larger size than most moles – >6 mm and often a centimetre or more in diameter at diagnosis
Dome-shaped, often symmetrical firm lump
Single colour or variable pigmentation – most often black, red or skin coloured
Smooth, rough, crusted or warty surface
Ulceration or bleeding
Itching or stinging
One-third of nodular melanomas are not pigmented. They lack the ABCD melanoma warning signs. (Asymmetry, Border irregularity, Colour variation, large Diameter).
What is the cause of nodular melanoma?
Nodular melanoma is due to the development of malignant pigment cells (melanocytes) along the basal layer of the epidermis. These cells may occasionally arise from an existing melanocytic naevus (about 3%) but commonly arise within another type of melanoma or in previously normal-appearing skin. What triggers the melanocytes to become malignant is unknown, but it is likely to be a series of changes to the DNA. NRAS mutations are often found in patients with nodular melanomas.
What tests should be done if I have nodular melanoma?
It is essential to diagnose nodular melanoma accurately. Clinical diagnosis is aided by dermoscopy and skin biopsy (usually excision biopsy). Those with melanoma that is more than 1 mm thick may be advised to have lymph node biopsy, imaging studies and blood tests.
Dermoscopy, or the use of a dermatoscope, by a dermatologist or other doctor trained in its use can be very helpful in distinguishing nodular melanoma from other skin lesions, such as:
Melanocytic naevi (moles)
Pigmented basal cell carcinoma
Vascular lesions such as angiomas and pyogenic granuloma.
The most frequently observed dermoscopic features of nodular melanoma are:
Disorganised asymmetrical structure
Atypical vascular patterns