Understanding Your Melanoma Diagnosis and Pathology Report
If your doctor identified a suspicious area on your skin and you had a biopsy or the suspicious area was removed, you will receive a pathology report (a medical document that describes the characteristics of a tissue sample or body fluid). The suspicious tissue was examined by a pathologist or dermatopathologist who looked at the tissue under a microscope and produced the pathology report for you and your doctor.
The purpose of the pathology report is to tell you and your doctor whether the tissue is benign (contains no cells that are suspicious for cancer) or malignant (sample contains cells that are consistent with cancer) and the characteristics of the suspicious tissue so that you and your doctors can decide on what might be next for your unique situation.
If it is cancer, know that every cancer is different. Understanding what’s in your pathology report is important because the information helps you and your doctor decide what’s best for you.
What kind of information is in a pathology report and what does it mean for you?
If the diagnosis is a melanoma, the information in your pathology report will describe the type of melanoma and certain features that help assess how aggressive it is such as tumor thickness and whether its ulcerated or not.
These features are used by the pathologist to stage the tumor. This pathology staging considers only the tumor itself and is different from the clinical staging, which involves looking whether or not the tumor has spread elsewhere in your body.
Information from other tests that are used in only some situations may also be present or may be obtained at a later time. All this information is used for deciding about whether further steps like additional surgery or treatments should be considered or not.
Sample Pathology Report
Below is a sample pathology report for a melanoma. As shown by the color code, the type of information in the pathology report tells you about:
Components of a pathology report
Your pathology report is likely to include:
Information about you
The report will include your name, date of birth, patient number or other identifier, and date of biopsy or surgery. You may also see information about biopsies and diagnoses you had in the past, if applicable.
General information about the tissue sample that was removed
If you had a biopsy (meaning that only part of the suspicious area was removed), the report will state what type of biopsy it was (examples: shave, punch, incisional, fine-needle aspiration). Alteratively, you may have had an excision (also called wide local excision), meaning the entire suspicious area was removed.
Body location where the tissue was removed (example: arm).
Gross description including the appearance of the area and its size (height, width, depth in mm or cm, measured before the tissue is sliced into thin slices for analysis under a microscope).
Microscopic description of what the tissue looks like under the microscope (example: atypical melanocytes).
Status of margins, which are the edges of the tissue sample. Options are involved or uninvolved, positive or negative, or clean. If you had an excision and the margins are positive, it is likely that not all the cancer was removed.some text
The deep margin is the bottom of the sample.
The peripheral margins are the side edges of the sample.
Information related to the type of melanoma
The report may describe the type of melanoma as cutaneous, acral, mucosal, uveal, desmoplastic, or nevoid melanoma (or Merkel cell carcinoma), depending upon features examined and the area of the body where the skin lesion resides.
Histologic types: The most common type of melanoma is cutaneous melanoma. Histologic types of cutaneous melanoma are superficial spreading (accounting for 70% of cases), nodular (accounting for 20% of cases), lentigo maligna, acral lentiginous, and desmoplastic. Some melanomas are determined to be amelanotic, meaning a melanoma that lacks melanin, the dark pigment that gives moles and melanomas their dark color. The histologic type is important information because there are differences in prognosis and treatment options for different types of melanoma.
In the case of a melanoma, the pathology report may tell you whether the tissue removed is a primary melanoma, which means the melanoma started in the location it was removed from. Alternatively, the tissue may be a metastatic melanoma deposit, which means that the melanoma started somewhere else on the body and then spread to the current location.
Final diagnosis (example: malignant melanoma).
Information related to the stage of melanoma
The stage of melanoma will be determined twice: the clinical stage is determined after a biopsy, and the pathologic stage is determined after surgery to remove the entire lesion. The American Joint Committee on Cancer (AJCC) Tumor Node Metastasis (TNM) staging system is used:some text
Clinical staging: designated with a lowercase “c” (example: cT1).
Pathologic staging: designated with a lowercase “p” (example: pN1).
You will see N/A or not known if T, N, or M was not assessed.
Breslow thickness and Clark level. These are measurements of how deep the melanoma has invaded into the skin. They have largely been replaced by the AJCC staging system but they may occasionally appear on your pathology report.
Maximum tumor thickness in millimeters (mm).
Ulceration: Breaking of the top layer of skin. Options are present or absent.
How aggressive it is
Mitotic index or mitoses: Given in number per square millimeter (mm2), this tells how fast the cancer cells are dividing.
Microsatellitosis or microscopic satellites: Small groups of tumor cells that have spread beyond the primary tumor found in the biopsy. Options are N/A or absent or present.
Lymphovascular invasion: The presence of tumor cells in blood vessels or lymphatic vessels. Options are present or absent.
Tumor regression: An area of tissue where it appears there had been melanoma cells, but they were destroyed by the immune system. Options are present or absent.
Tumor infiltrating lymphocytes (TILs): TILs are immune system cells. The presence of TILs is generally a favorable sign. Options are present or absent. If present, options are brisk, non-brisk, or sparse.
Other situations
Certain tests are ordered only in particular situations. Results from the below tests are not part of every pathology report but may be reported at a different time. Some pathology reports may include the following:
When a possible diagnosis of melanoma is not certain
About 15% of moles and pigmented lesions that are suspicious are difficult to diagnose, even by a trained dermatologist. Additional tests the dermatologist may use include dermascopy, optical coherence tomography (OCT), or if a biopsy is taken, a gene expression profiling (GEP) test.
Dermtech’s 2-GEP Pigmented Lesion Assay can be used by a dermatologist to help determine whether or not to biopsy a suspicious-looking mole.
Myriad Genetic’s myPath® Melanoma can be used in addition to examining the tissue under a microscope when the distinction between a benign mole and a malignant melanoma cannot be made confidently by microscopic examination alone. The test measures 23 genes and accurately distinguishes melanoma from a benign mole.
For early-stage melanoma and uveal melanoma
A commercially available GEP test, also called a genomic test, can help predict the risk of recurrence for early-stage melanoma. The test measures several genes associated with risk of melanoma metastasis (spreading to other parts of the body). By comparing the levels of expression of each gene, the test can better classify your risk. While promising, clinicians are divided on the accuracy and utility of these GEP tests for cutaneous (skin) melanoma. Your doctor may or may not order these types of tests. In uveal (eye) melanoma, prognostic tests are a routine part of standard of care and are recommended by expert groups.
Castle Biosciences DecisionDX®-Melanoma can be used by a doctor for patients with a confirmed melanoma diagnosis to assess risk of recurrence.
Castle Biosciences DecisionDX®-UM (uveal melanoma) is routinely used by doctors to estimate the risk of recurrence and/or metastasis for patients diagnosed with uveal melanoma.
For advanced melanomas
If you have metastatic melanoma (stage 4; melanoma that has spread), it is vital to have a biopsy of your metastatic tumor and appropriate comprehensive biomarker testing (example: genomic testing), as well as all other appropriate tests recommended by your doctor as early as possible to help determine your best treatment options.
If you have stage 3 or 4 melanoma, you will likely be tested for mutations in genes named BRAF, NRAS, and KIT. The results will help you and your doctor make treatment decisions because drugs have been developed that specifically target cancer cells with these mutations.
Genomic testing: Genomic testing for metastatic (stage 4) melanoma can identify the BRAFV600E mutation1. Targeted therapies are available for tumors with this mutation.
Imaging scans such as MRI and PET-CT. Thesare used to see if melanoma has spread to other parts of the body.
The PD-L1 immunohistochemistry test may be ordered for melanoma to determine eligibility for immunotherapy treatment.
Lymph nodes may be examined for the presence of cancer cells.
Treatment effect: If you had treatment before surgery to remove the cancer, which doctors call neoadjuvant treatment, your report will have this section. It usually includes:some text
Tumor bed size: The overall size of any remaining cancer found during surgery after neoadjuvant treatment.
Tumor bed cellularity: The percentage of cancer cells found in the tumor bed.
If no cancer is found after neoadjuvant treatment, the pathologist will say no residual carcinoma. You may see “N/A” if you did not receive neoadjuvant therapy.
ctDNA testing: Also known as a liquid biopsy, ctDNA detects cancer cell DNA in the blood. ctDNA testing in stage 4 melanoma can be used for several purposes including monitoring for progression of the cancer in people who are receiving immunotherapy.
