Vulvar cancer is diagnosed through a combination of physical examination and biopsy, with the biopsy being the only way to confirm the diagnosis. Most cases are caught when a woman notices changes in the vulvar skin or reports persistent itching, and a doctor takes a small tissue sample for lab analysis. When caught at a localized stage, the five-year survival rate is about 86%, but that drops to roughly 50% when the cancer has spread to nearby lymph nodes, making early and accurate diagnosis critical.
The Physical Exam
Diagnosis typically starts with a thorough physical exam of the vulva and surrounding lymph nodes. Your doctor is looking for anything unusual: a lump, an open sore that won’t heal, changes in skin color or texture, or thickened patches of skin. Many of these findings overlap with benign conditions like lichen sclerosus (a chronic skin condition that causes white, thin patches), which is one reason a visual exam alone can’t confirm cancer.
To get a closer look, your doctor may use a magnifying instrument in a procedure called vulvoscopy. During this exam, a dilute acetic acid solution (essentially vinegar) can be applied to the skin. Areas with precancerous changes or cancer turn white under this solution, making them easier to identify. Less commonly, a blue dye called toluidine blue is used instead, which stains abnormal skin blue. Both techniques help pinpoint exactly where to take a tissue sample.
Biopsy: The Definitive Step
No matter how suspicious a lesion looks, a biopsy is required to confirm vulvar cancer. The most common method is a punch biopsy, which uses a small pen-sized instrument with a circular cutting edge. The doctor twists it into the skin to remove a tiny cylinder of tissue, typically 4 to 5 millimeters across. That’s small enough to cause minimal discomfort and rarely needs stitches, but large enough to give the pathologist a reliable sample.
The biopsy site is numbed with local anesthetic beforehand. If a lesion is large or has areas that look different from one another, your doctor may take multiple samples from different spots to avoid missing a more aggressive area. The tissue sample includes the edge of the lesion, which helps pathologists see the boundary between normal and abnormal cells.
What Recovery Looks Like
Recovery from a vulvar biopsy is straightforward. You can shower the same day; just pat the area dry gently. Keeping the site clean and dry is the main priority. If urination stings the biopsy spot, a thin layer of petroleum jelly can help. When stitches are needed, they’re usually the dissolvable kind.
Contact your doctor if you notice redness, swelling, warmth around the site, foul-smelling discharge, heavy bleeding, or a fever of 100.4°F or higher in the 10 days after the procedure. A fever above 102°F or severe pain in the first three days warrants an emergency room visit.
What the Pathologist Looks For
Once the tissue sample reaches the lab, a pathologist examines it under a microscope to determine whether cancer cells are present. But the analysis goes further than a simple yes or no. The World Health Organization now classifies vulvar squamous cell carcinoma into two main categories: HPV-associated and HPV-independent. This distinction matters because the two types behave differently and may call for different treatment approaches.
To sort this out, pathologists stain the tissue with two protein markers. One marker, called p16, acts as a reliable stand-in for high-risk HPV infection. The other, p53, helps identify cancers driven by a specific gene mutation rather than a virus. Together, these markers place the cancer into one of three groups: HPV-associated (p16 positive, normal p53), HPV-independent with a TP53 mutation (p16 negative, abnormal p53), or HPV-independent without a TP53 mutation. Both markers need to be tested together. Using p16 alone can lead to misclassification, which could affect treatment decisions.
Checking the Lymph Nodes
If the biopsy confirms cancer, the next question is whether it has spread to nearby lymph nodes. The answer depends on how deeply the tumor has invaded the tissue. When invasion depth is less than 1 millimeter, the risk of lymph node spread is negligible, so lymph node testing generally isn’t needed.
For tumors that invade more than 1 millimeter but are smaller than 4 centimeters, and there are no suspicious lymph nodes on exam or imaging, a sentinel lymph node biopsy is the standard approach. This procedure identifies and removes the first lymph node(s) where cancer would drain, sparing the patient a more extensive surgery. If the sentinel node is clear, the remaining nodes are left alone. If cancer is found, a fuller lymph node removal may follow.
Imaging Tests for Staging
Not every vulvar cancer diagnosis requires imaging. But for larger or more advanced tumors, imaging helps doctors understand exactly how far the cancer extends and whether it has reached distant sites.
MRI is the preferred tool for evaluating local spread because it provides the best soft-tissue detail. It’s particularly useful when the tumor is larger than 2 centimeters or sits close to the urethra, vagina, or anus, since it can show whether those structures are involved. CT scans, by contrast, aren’t very helpful for assessing the primary tumor itself due to their limited ability to distinguish between soft tissues.
For tumors larger than 4 centimeters, or any tumor that involves nearby structures beyond minimal contact, doctors typically combine an MRI of the pelvis with a PET/CT scan from the skull base to mid-thigh. The MRI maps the local tumor, while the PET/CT detects cancer in lymph nodes or distant organs by highlighting areas of unusually high metabolic activity. A contrast-enhanced CT of the chest, abdomen, and pelvis is a reasonable alternative when MRI isn’t available. PET/CT is also the go-to scan when doctors suspect the cancer has come back after treatment.
Why Conditions Like Lichen Sclerosus Complicate Diagnosis
One of the challenges in diagnosing vulvar cancer is that several benign conditions can look similar. Lichen sclerosus, a relatively common inflammatory skin condition, causes itching, white patches, and skin thinning on the vulva. These symptoms overlap with early vulvar cancer, and the two conditions aren’t entirely unrelated. Lichen sclerosus is associated with a type of precancerous change called differentiated vulvar intraepithelial neoplasia, which can progress to a keratinizing form of squamous cell carcinoma.
Research has found genetic and epigenetic links between lichen sclerosus and HPV-independent vulvar cancer, including shared mutations in the TP53 gene. Both conditions also show a reduction in certain immune cells in the skin, suggesting a weakened local immune response that may contribute to cancer development. This is why persistent or changing vulvar symptoms in someone with lichen sclerosus often prompt a biopsy, even if the condition has been stable for years. The visual appearance alone can’t reliably distinguish inflammation from early malignancy.
How Stage Affects Outlook
Staging is based on how far the cancer has spread at diagnosis, and it has a dramatic effect on prognosis. According to the National Cancer Institute’s SEER database (covering 2015 to 2021), the five-year relative survival rate for localized vulvar cancer, meaning it hasn’t spread beyond the vulva, is 85.7%. Once the cancer reaches regional lymph nodes, that drops to 49.7%. For distant disease, the five-year survival rate falls to 21.9%. These numbers underscore why the diagnostic process doesn’t stop at confirming cancer. Accurately determining the stage through biopsy, lymph node assessment, and imaging shapes the entire treatment plan.