Stage 3 melanoma doesn’t have one single appearance. What defines it isn’t how the primary skin lesion looks, but the fact that cancer cells have spread beyond the original spot to nearby lymph nodes or surrounding skin. The primary tumor itself can range from a small, thin lesion to a thick, ulcerated mass, and the most telling visual signs often show up not at the original mole but in the skin nearby or in swollen lymph nodes.
What Makes Melanoma “Stage 3”
The key distinction between stage 2 and stage 3 melanoma is spread. In stage 3, cancer has reached at least one nearby lymph node or has produced small secondary tumors in the skin between the original melanoma and the nearest lymph node basin (typically in the groin, armpit, or neck area). It has not spread to distant organs, which would make it stage 4.
This spread is sometimes visible to the naked eye and sometimes completely invisible. In many cases, melanoma cells are only detected through a sentinel lymph node biopsy, a procedure where the first lymph node draining the tumor site is surgically removed and examined under a microscope. A positive result on this biopsy is what tips the diagnosis from stage 2 to stage 3, even when the lymph node felt completely normal on physical exam.
The Primary Tumor’s Appearance
The original melanoma in stage 3 can look dramatically different from person to person. It may be a flat, irregularly shaped dark patch, a raised bump, or a thick nodule that has grown rapidly over weeks to months. Colors range from dark brown or black to blue-black, and some melanomas contain a mix of shades including red, white, or tan areas where the pigment is uneven.
Roughly one-third of nodular melanomas (a fast-growing subtype) are amelanotic, meaning they have no dark pigment at all. These can appear pink, red, or skin-colored, which makes them easy to mistake for a benign bump or sore. An ulcerated surface, where the skin over the tumor has broken down and may bleed or ooze, is common at this stage. Among stage 3 patients, about 65% have ulcerated tumors.
Thickness matters. Stage 3 tumors span a wide range. Some are 1 millimeter or less, while others exceed 4 millimeters deep. The median thickness for stage 3 melanomas with ulceration is around 5 millimeters, roughly the thickness of two stacked nickels. Thicker tumors tend to feel firm or raised and are more likely to have an uneven, dome-shaped, or mushroom-like profile. Thinner tumors at stage 3 are still dangerous because they’ve already demonstrated the ability to spread to lymph nodes despite their small size.
Satellite and In-Transit Lesions
One of the most visually distinctive features of stage 3 melanoma is the appearance of satellite or in-transit metastases. These are small secondary tumors that show up in the skin or just beneath it, located between the original melanoma and the nearest lymph node basin. Satellite lesions sit within 2 centimeters of the primary tumor, while in-transit metastases appear farther away along the path toward the lymph nodes.
These lesions typically look like small, firm nodules or bumps in or under the skin. They can be skin-colored, pink, blue, or dark, and they may appear singly or in clusters. Some are visible on the surface, while others can only be felt as hard lumps beneath otherwise normal-looking skin. Their presence automatically qualifies a melanoma as at least stage 3B, regardless of the primary tumor’s size.
Swollen Lymph Nodes
Enlarged lymph nodes near the melanoma are one of the most noticeable physical signs of stage 3. You might feel a firm, painless lump in your armpit, groin, or neck, depending on where the original melanoma is located. These swollen nodes can range from the size of a pea to much larger, and they tend to feel hard and fixed rather than soft and movable.
Not all affected lymph nodes are detectable by touch. Melanoma can be present in lymph nodes that feel completely normal on examination. This is why sentinel lymph node biopsy plays such a central role in staging. When lymph nodes are palpable (meaning a doctor can feel them), they’re surgically removed. But even non-palpable nodes can harbor cancer cells that only show up under a microscope.
Sub-Stages and What They Mean
Stage 3 is divided into four sub-stages, IIIA through IIID, based on tumor thickness, ulceration, and how many lymph nodes are involved.
- Stage IIIA: The least advanced. The primary tumor is 2 millimeters or less (with ulceration) or up to 2 millimeters (without), and cancer is found in 1 to 3 lymph nodes only through biopsy, not by physical exam.
- Stage IIIB: The tumor may be up to 4 millimeters thick, cancer is found in 1 to 3 lymph nodes by exam or imaging, or satellite and in-transit lesions are present in the skin.
- Stage IIIC: More lymph nodes are involved (4 or more), or nodes are matted together, or there’s a combination of lymph node spread and satellite or in-transit lesions. Thicker, ulcerated tumors with any node involvement also fall here.
- Stage IIID: The most advanced sub-stage. The primary tumor is thicker than 4 millimeters with ulceration, and cancer is found in 4 or more lymph nodes or matted nodes, with possible satellite or in-transit metastases.
The visual and physical differences between these sub-stages can be subtle. A person with stage IIIA might have a small, relatively flat melanoma with no visible lymph node swelling, while someone with stage IIID could have a large, ulcerated, bleeding mass with multiple visible skin nodules and obviously swollen lymph nodes. Both are stage 3, but they look and feel very different.
Signs That May Not Be Visible
One of the challenging realities of stage 3 melanoma is that much of what defines it isn’t visible on the surface. A thin melanoma that looks relatively small and contained may have already seeded cancer cells into lymph nodes. The original lesion might even have regressed or partially faded, making it harder to see, while the disease has quietly progressed beneath the skin.
This is why staging relies heavily on biopsy results and imaging rather than appearance alone. If you’ve had a melanoma removed and your doctor recommends a sentinel lymph node biopsy, the results of that procedure determine whether you’re stage 2 or stage 3, regardless of how the original spot looked.
Survival Outlook for Stage 3
The five-year relative survival rate for stage 3 (regional) melanoma is about 60%, according to data from the National Cancer Institute’s SEER program. This number reflects outcomes across all sub-stages, so it’s an average. Stage IIIA carries a significantly better prognosis than IIID. Treatment advances in immunotherapy and targeted therapy over the past decade have improved outcomes substantially, and many people with stage 3 melanoma live well beyond five years, particularly when treatment begins promptly after diagnosis.