Nodular Malignant Melanoma of Skin

This is a variation of malignant melanoma and so should be read in conjunction with that article. In this variety the malignant cells grow vertically down through the dermis.

Nodular melanoma represents about 25% of all malignant melanoma.

• It is an aggressive tumour.
• It tends to occurs in a younger age group.
• It affects males twice as often as females.
• There is early vertical growth.
• It is usually uniform in colour with early ulceration and bleeding.

The lesion is usually a papule or nodule with or without surrounding irregular pigmentation. The colour ranges from dark brown to black. Sometimes the lesion is red and vascular due to lack of melanin and this is called "amelanotic melanoma". The surface of the nodule may break down to produce an ulcer, with exudate, blood or crust on the surface.

Most melanomas arise in the skin but they can arise from mucosal surfaces. More than half of the cases arise in apparently normal areas of skin. Early signs to suggest malignant change include darker or variable discoloration, itching, an increase in size or the development of satellites. Ulceration or bleeding are later signs.

Clinical suspicion of malignant melanoma is discussed in the article with particular reference to the 7 point check list of 3 major and 4 minor features from the British Association of Dermatologists.¹ They are repeated here:

• Major:
  • Change in size
  • Irregular shape
  • Irregular colour
• Minor:
  • Largest diameter 7mm or more
  • Inflammation
  • Oozing
  • Change in sensation

The aetiology is as with other malignant melanoma. Radiation, especially sunlight, is important, especially on fair skin. They do sometimes occur in areas that do not get much exposure, such as the vulva or sole of the foot.

Suspicious lesions should be excised for histology.

Excision can be done in general practice provided that there is full thickness excision to include a clinical margin of 2 to 5mm and a cuff of subdermal fat but if suspicion is high the patient should be referred intact. Punch, shave or biopsies that do not attempt to take the full lesion should not be attempted and they may make it impossible to stage the lesion. Biopsy of suspicious subungual lesions should be left to the experts. In a number of areas referral can be made to GPs with Special Interests in pigmented lesions. They provide an enhanced service probably through local based commissioning in keeping with the policy of movement from secondary to primary care.

Tissue must be adequately fixed and sent for histology. If more than one site is biopsied, specimens must be clearly labelled.

There is a direct correlation between the depth of invasion of the tumour cells and prognosis. Lesions deeper than 3mm have very poor prognosis. For this reason it is important that malignant melanomas are removed as early as possible. This is discussed much more fully in the article on malignant melanoma.

• A biopsy has been performed and the result shows a malignant melanoma. Even if it is said to have been excised completely, refer to a plastic surgeon.
• If malignancy is suspected but the site is such that the doctor in primary care does not feel competent to proceed, refer to a plastic surgeon. This may include lesions on the pinna or close to the eye.
• If the doctor does not feel personally competent to proceed and take a wide biopsy, refer to a dermatologist or GPSI for pigmented lesions.