Differential diagnosis of melanoma

Assessment considers a lesion’s symmetry, border, colour pattern, size, evolution and whether it differs from a person’s other moles. It also considers bleeding, persistent itching, a sore that does not heal, a firm nodule and lesions under a nail or on less visible skin. These signs can raise concern, but none confirms melanoma by itself.

Benign moles, seborrhoeic keratoses, sun-related pigmentation and some non-melanoma skin cancers can mimic melanoma. A clinician may use dermoscopy to inspect structures beneath the surface. If the lesion remains concerning, surgical excision or another biopsy provides tissue for a pathologist to examine. The tissue result, rather than visual appearance alone, establishes the diagnosis.

Arrange review for a new or changing mark and bring a record of when you first noticed it. Avoid picking or attempting to remove it. A clinician may photograph or measure the lesion, examine nearby skin and lymph nodes, and recommend removal of the whole lesion when feasible. If melanoma is confirmed, further surgery or staging tests depend on its depth and other findings.

Treatment plans may include skin cancer surgery, sentinel lymph node biopsy or systemic treatment such as immunotherapy. These choices are individual and should follow the pathology and specialist assessment.

Book a prompt dermatology appointment for a spot that changes in colour, outline, size or sensation, or for a dark mark that bleeds or remains open. Seek urgent help for sudden severe symptoms such as confusion, weakness, seizure or a severe new headache, especially in someone already diagnosed with melanoma. Do not wait for a lesion to become painful before arranging assessment.

Ask what features make the lesion concerning, whether dermoscopy or biopsy is needed, how much skin may be removed, when pathology will be available, and whether lymph-node assessment or follow-up is appropriate. Ask which symptoms should prompt an earlier review.