What should you know about melanoma of unknown primary?

A biopsy may show melanoma in a lymph node, skin site or another organ even though no original skin, eye or mucosal lesion is found. The original lesion may have regressed, been removed or been too small to recognise. “Unknown primary” describes what has not been located; it does not mean that the biopsy result is uncertain.

Doctors review the pathology, examine the skin and mucosal surfaces, ask about previous lesions and select scans according to the findings. The goal is to learn where melanoma is present, whether it has spread and which features may influence treatment.

Keep appointments with the dermatology or oncology team and bring details of previous moles, biopsies and operations. You may be offered imaging, a pathology review or a [Sentinel Lymph Node Biopsy](/treatments/diagnostics-and-staging/sentinel-lymph-node-biopsy/) depending on the situation. Treatment can include surgery to remove accessible disease, medicine such as [Immunotherapy](/treatments/systemic-therapy/immunotherapy/) or a combination. The plan is based on the actual sites involved, not on guessing where the original tumour began.

Contact your care team promptly for a new or enlarging lump, worsening pain, unexplained bleeding, persistent vomiting, severe headache, new weakness, confusion, breathing difficulty or a marked change in vision. Seek emergency help for sudden neurological symptoms or severe breathing trouble. These symptoms require assessment because they may have causes unrelated to melanoma as well as causes requiring urgent treatment.

Ask where the biopsy-proven melanoma was found, which examinations and scans are planned, whether the pathology has been reviewed, and what stage is being considered. Ask what treatment is intended, how response will be checked, what symptoms require urgent contact and how [Follow-Up After Cancer Treatment](/treatments/survivorship-and-rehabilitation/post-treatment-surveillance/) will be organised.