Diagnosis and management of melanoma

Any suspicious pigmented lesion for which melanoma cannot be clinically excluded requires a histological diagnosis by complete surgical excision, or referral for specialist assessment.

The initial excision excludes or confirms the diagnosis of melanoma. It should be done with a 2 mm lateral margin, preferably excised as an ellipse, with a deep margin in the subcutaneous fat, and repaired by primary closure.

Partial biopsy (by punch, shave, or incisional biopsy) is not usually recommended because it is associated with false negative results from sampling error. Partial biopsies should only be performed if complete excision is too difficult (eg a large pigmented lesion on the face). These partial biopsies are usually performed by a specialist or under specialist supervision.

If melanoma is confirmed, and some of the lesion was left behind after the initial excision, definitive wide local excision should be performed as soon as practicable (ideally within 4 weeks). Definitive wide local excision margins are mainly determined by tumour thickness, although margins may be modified taking into consideration melanoma subtype and histology, anatomical site, functional considerations and patient factors (eg age, comorbidities, immunosuppression). See Recommended wide local excision margins for melanoma for recommended melanoma excision margins. The excision depth should be the same as the lateral margin if possible, but no further than the deep fascia.

If the melanoma is greater than 1 mm thick, or greater than 0.75 mm thick with other high-risk pathological features (eg ulceration, mitotic rate greater than 1, Clark level IV or V, lymphovascular invasion), refer the patient to a multidisciplinary specialist melanoma unit (consisting of surgical, radiation and medical oncologists) for consideration of sentinel lymph node biopsy, which is performed at the same time as the primary wide local excision. Sentinel lymph node status is a predictor of melanoma-specific survival for patients with melanoma greater than 1 mm in thickness.

If metastasis is suspected, refer the patient to a multidisciplinary specialist melanoma unit. The management of unresectable advanced or metastatic melanoma is a rapidly evolving field, with new and effective systemic therapies, such as targeted therapies (BRAF and MEK inhibitors) and immunotherapy (CTLA-4 and PD-1 checkpoint inhibitors).

Inform patients with melanoma that they are at risk of further melanoma and nonmelanoma skin cancers, and will require lifelong surveillance. Frequency of follow-up depends on the stage of the patient’s melanoma (see the Melanoma Institute Australia website for detail of stages):

• Stage I: annually
• Stage IIA: every 6 months for 2 years, then annually
• Stage IIB and IIC: every 3 to 4 months for 2 years, every 6 months in year 3, then annually
• Stage IIIA to IIIC: every 3 months for 2 years, every 6 months during year 3, then annually.

Immediate family members (ie first-degree relatives) of a patient with melanoma should also have regular skin surveillance because they have an increased risk of melanoma.