The short answer
Satellite, microsatellite, and in-transit metastases are small groups of melanoma cells found in the skin or under it, away from the main tumor but not in the lymph nodes. NCI defines each by where it is. They are counted in the N category. Without distant spread, that is stage III. This page explains the terms.
These terms describe small groups of melanoma cells near the main tumor, in the skin or lymph vessels, but not in lymph nodes.
NCI defines them by distance: satellite tumors are within 2 cm, in-transit metastases are more than 2 cm away.
They are counted in the N category. If there is no distant spread, this places the melanoma in stage III.
What happens next depends on the full report. Your care team explains the options.
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This page is for anyone whose melanoma report mentions a satellite, microsatellite, or in-transit metastasis. It explains what each term means and how it fits into staging.
Three terms for spread near the main tumor
Melanoma cells can travel through tiny lymph vessels in the skin. Sometimes they stop and form small spots before they reach any lymph nodes. NCI uses three terms for these spots, based on where they are:
- Satellite tumors: "small groups of tumor cells that have spread within 2 centimeters of the primary tumor."
- Microsatellite tumors: "small groups of tumor cells that have spread to an area right beside or below the primary tumor." These are usually found under the microscope.
- In-transit metastases: "tumors that have spread to lymph vessels in the skin more than 2 centimeters away from the primary tumor, but not to the lymph nodes."
The "primary tumor" is the main melanoma. A centimeter is a little less than half an inch.
Where they fit in staging
These spots are counted in the N category of TNM staging, the same part that covers lymph nodes. In NCI's staging table, the letter "c" (for example N1c, N2c, or N3c) means satellite, microsatellite, or in-transit metastases are present.
- N1c means these spots are present but no lymph nodes are involved.
- N2c and N3c mean these spots are present along with one or more involved lymph nodes.
If there is no distant spread (M0), any N category above N0 places a melanoma in stage III. The exact stage III group depends on the T category, the N category, and other details.
What this does and does not mean
These terms describe spread in the skin near the main tumor. They do not mean the melanoma has spread to distant organs. That is described by the M category.
A stage III finding can feel frightening. Stage describes groups of people, and many things shape each person's plan. Your care team can explain what your report means for you and which tests or treatments they suggest.
If you notice new spots
If you notice a new bump, lump, or colored spot on your skin near the scar, or anywhere else, tell your care team. Do not wait for your next visit.
Ask these before you leave
- Which term is on my report, and where was the spot found?
- What N category and stage do I have?
- Were lymph nodes checked, and what did they show?
- Do I need more scans or tests?
- What treatment options fit this finding?
Related pages
See Melanoma Stages, What Does N Stage Mean?, What Lymph Node Involvement May Mean, and Sentinel Lymph Node Biopsy for Melanoma.
Sources
Common questions
What is an in-transit metastasis?
NCI describes it as melanoma that has spread to lymph vessels in the skin more than 2 centimeters from the main tumor, but not to the lymph nodes.
What is a satellite or microsatellite?
A satellite is a small group of tumor cells within 2 cm of the main tumor. A microsatellite is a small group of tumor cells right beside or below the main tumor, usually seen only under the microscope.
Does this mean the melanoma has spread far?
These terms describe spread near the main tumor, not to distant organs. Your care team will explain whether other tests are needed.
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Sources last checked: 2026-09-27 what this meansLast updated: 2026-09-27Next planned review: 2027-09-27
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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