What Does A Pathology Report Tell You?
Skin samples taken by a biopsy or surgical excision are typically sent to a pathology laboratory for microscopic examination and diagnosis. A pathology report is issued by a pathologist or dermatopathologist.
A pathologist is a physician who diagnoses disease through laboratory tests and direct evaluation of cells, tissues, and organs. A dermatopathologist specializes in skin pathology, a subspecialty of dermatology and pathology.
The pathology report states the diagnosis and further describes any defining characteristics of the melanoma, such as the type of melanoma, depth of invasion, presence or absence of ulceration, mitotic count, presence or absence of regression, presence or absence of satellite lesions, and presence or absence of blood vessel/lymphatic vessel/nerve invasion.
Additionally, the pathology report will indicate whether the excised lesion is a primary melanoma, in which case it would be described using the terms above, or a metastatic melanoma deposit. A metastatic melanoma deposit is one in which the melanoma started somewhere else on the skin and some of the melanoma cells broke off and spread within the skin tissue to the current biopsy/specimen site.
An Example of a Melanoma Pathology Report
The following information (in purple) is from an actual melanoma pathology report. Not all pathology reports will have all of these details, but this sample report should help you decipher yours.
The report will begin by identifying you, your specimen, and your doctor (or the person who ordered the report):
DATE OF BIOPSY:
(your physician’s name)
(a number assigned to the biopsy specimen used to identify it in the pathology system)
(medical record number)
There will be a diagnosis section, usually near the top of the report:
FINAL PATHOLOGY DIAGNOSIS: Right anterior distal thigh excisional biopsy; 1.5 x 1.7cm. MALIGNANT MELANOMA, NODULAR TYPE, BRESLOW THICKNESS AT LEAST 2.6MM, WITHOUT ULCERATION, BIOPSY EDGES ARE INVOLVED.
This section will typically state the type of excision and the location on the body of the biopsy, as well as the final pathologist opinion of the diagnosis of melanoma, and the type of melanoma. The Breslow thickness will be noted somewhere on the report—here or elsewhere, or both—because this measurement of the melanoma’s thickness is one of the most important details for diagnosis. Other important details about the melanoma, such as ulceration, may also be here.
CLINICAL HISTORY: Neoplasm of uncertain behavior; Melanoma vs. Nodular melanoma
The Clinical History is a description by your physician of the lesion that was biopsied. This description may include size, location, and/or what s/he is concerned about. In this case, it appears nodular melanoma was suspected.
MICROSCOPIC/DESCRIPTION: Microscopic examination has been performed and is consistent with the diagnosis. The tissue sample was received in the bottle labeled “right anterior distal thigh.” The tissue demonstrates a malignant melanocytic neoplasm. There are nests of atypical melanocytes filling the papillary and reticular dermis demonstrating a compact cohesive growth pattern with scattered mitoses, pleomorphic nuclei and prominent nucleoli with lack of maturation. There is no evidence of regression or pagetoid invasion noted. There is an intact epidermis with a junctional component identified. There is no ulceration, satellites, perineural or lymphovascular invasion identified in the tissues examined. As the lesion involves the deep margin, the lesion measures at least 2.6mm in depth and is at least Clarks’s level IV with the staging of at least pT3aNxMx. The lateral margin was additionally positive and involved with melanoma in situ. Correlation with larger excisional specimen is recommended due to the positive deep and lateral margins, as well as for further staging purposes. This case was reviewed by my colleague Dr._________ who concurs with the above interpretation.
These sections confirm the microscopic examination and the finding of melanoma. In many reports this section can be quite detailed, with very specific description of the appearance of the cells and characteristics about how the cells look under the microscope.
The rest of the report will describe the specifics about the melanoma in detail:
HISTOLOGIC TYPE: Nodular melanoma
Histologic type can be superficial spreading, nodular, lentigo maligna, acral lentiginous, desmoplastic, unclassified, etc. Histologic type is the type of melanoma you have. It’s important information because there are prognostic and treatment differences in different types of melanoma.
MAXIMUM TUMOR THICKNESS: At least 2.6mm
This thickness is also called Breslow Thickness or Breslow Depth. It describes in millimeters the thickest part of the melanoma. This measurement is very important for prognosis. A thinner tumor has a better prognosis.
ULCERATION: Not identified.
Ulceration is the breakdown or loss of the top layer of the skin (the epidermis). The pathologist/dermatopathologist determines the presence or absence of ulceration when s/he reviews the specimen under the microscope. Having ulceration is associated with a worse prognosis. Patients who report bleeding from their melanoma often have ulceration in the biopsy.
PERIPHERAL MARGIN: Involved by invasive melanoma; involved by melanoma in situ.
DEEP MARGIN: Involved by invasive melanoma.
Margins are the edge of a biopsy or surgical excision specimen. If melanoma extends to the edge of the sample (the margins), then it is presumed that the biopsy or excision did not remove the entire tumor. Deep margins are located at the base of the biopsy/specimen and lateral/peripheral margins are the side edges of the biopsy/specimen. If there is no tumor extending to the margins, the pathologist will describe how close the lesion came to the edge. (Example: tumor extends to within 2 mm of the margin). The thickness of the melanoma is used to guide the recommended margin of normal tissue the surgeon plans to remove at the time of surgery.
LYMPHOVASCULAR INVASION: Not identified.
Blood vessel/lymphatic or lymphovascular invasion means that melanoma cells have entered the blood vessels or lymphatic system. The presence of this finding is associated with a worse prognosis.
PERINEURAL INVASION: Not identified.
If identified, perineural invasion is evidence that melanoma cells are entering the local nerve fibers. The presence of this finding is associated with a worse prognosis.
TUMOR REGRESSION: Not identified.
Regression refers to an area of the tumor without active melanoma cell growth and is thought to be evidence that some of the melanoma was destroyed by one’s immune system. There are conflicting reports on whether this finding has useful prognostic significance.
AJCC STAGE/TNM: pT3a
The TNM System (Tumor-Node-Metastasis) is the most widely used way of determining cancer stages. This staging system, created by the American Joint Committee on Cancer (AJCC), provides important prognostic and survival information. The “T3a” describes this patient’s tumor depth and lack of ulceration. The “p” means that there is a pathology report to support the staging assigned. If there is an “x” noted in one or more of the categories, such as above in the Microscopic/Description section where the staging is noted as “pT3aNxMx” it means that there has been no assessment of that characteristic of the tumor.
COMMENT: There is local superficial erosion, consistent with trauma/irritation.
In the case of melanoma, pathologists will specifically comment on features that are relevant for prognosis and treatment. These are sometimes included in the description but also may be in list form.
GROWTH PHASE: Vertical
Radial growth phase and/or vertical growth phase may be noted, describing whether the melanoma has begun an invasive pattern. If the melanoma has a Breslow depth, then it will have a vertical growth phase even if this is not separately reported.
MITOTIC RATE: 3/mm2
Mitosis is the process by which one mature cell divides into two identical cells. The pathologist counts the number of actively dividing cells (mitoses) that they see. This is seen in many cancers, including melanoma. Averaging this number gives the mitotic count, which is stated as the number of mitoses per square millimeter (mm). A higher mitotic count means more tumor cells are dividing at a given time and is associated with a worse prognosis.
GROSS: Received in formalin labeled with the patient’s name and the anatomic site are 2 superficial pieces of skin ranging in size from .8 cm by 0.3 cm by 0.1 to 1.4 cm by 1.0 cm by 0.3 cm. the specimens are sectioned and submitted entirely in 1 cassette. The measurements may not correspond to those in vivo as shrinkage from formalin fixation may occur.
Gross is a description of the actual size of the biopsied tissue and what it looked like to the naked eye. This section is used by the pathologist for identification of the tissue.
Other Details That May Be On Your Pathology Report Include The Following:
Clark Level/Level of Invasion/Anatomic Level:
Clark Level was replaced in the revised melanoma staging system in 2010 by more reliably predictive features (mitotic count and ulceration). It is now only used to stage thin melanomas (< 1mm).
Tumor Infiltrating Lymphocytes (TILs):
Lymphocytes are immune cells. Lymphocytes can be present in a melanoma and are described as “brisk,” “non-brisk,” “sparse,” and “absent.” A brisk immune response has been associated with a better prognosis. However, the true significance of this criterion is still controversial, and some pathologists do not report it.
Also called “local metastasis.” They are small nodules of melanoma located more than 0.05mm from the primary lesion but less than 2cm. They are described as being present or absent. Some satellite lesions (macroscopic) can be seen with the naked eye. Others, which are smaller (microscopic) can be found only by the pathologists. Both macroscopic and microscopic lesions are reported in the pathology report.
Based on all the above information, the pathologist may make initial recommendations to the doctor, including whether another biopsy needs to be done to get additional tissue, or whether the doctor should perform an excision of the lesion to ensure complete removal.