Tests and Exams for Melanoma Work-up (Diagnosis and Evaluation)

How Is Melanoma Diagnosed?

A new lesion, or spot, or growth on your skin raises the possibility of melanoma. Your doctor will do an examination and other various tests will be used to find out whether it is melanoma, nonmelanoma, or some other skin condition. A specific diagnosis can only be made by doing a skin biopsy.

History and Physical Examination

Usually the first step is for your doctor to take your medical history (questions about symptoms and risk factors). The doctor will ask when the skin lesion first appeared and whether it has changed in size or appearance. You may also be asked about past exposures to known causes of melanoma and whether anyone in your family has had melanoma.

During the physical examination, your doctor will note the size, shape, color, and texture of the area in question and look for any bleeding or scaling. The rest of your body will be checked for spots and moles that may be related to melanoma. The doctor will also examine lymph nodes in areas near the abnormal area of skin. Lymph nodes, also called lymph glands, are small bean-shaped collections of immune system tissue that are found along lymphatic vessels. Enlarged lymph nodes might suggest the spread of a melanoma to these structures.

Seeing a Specialist

If your doctor is not a specialist in skin disorders (dermatologist), you may be sent to one for further evaluation and a biopsy.

Types of Skin Biopsy

If the doctor thinks a melanoma might be present, he or she will take a sample of skin from the suspicious area for examination under a microscope. This is called a skin biopsy. Different methods can be used. The choice depends on the size of the affected area and its location on your body. Any biopsy is likely to leave a scar. Because different methods produce different types of scars, you should ask the doctor about biopsies and scarring before the procedure is done. Skin biopsies are done using a local anesthetic. You will typically feel a small needle stick and a little burning with some pressure for less than a minute.

All skin biopsy samples are examined under a microscope. The skin sample is sent to a pathologist, a doctor who has been specially trained in the microscopic examination and diagnosis of tissue samples. Often, the skin sample is sent to a dermatopathologist, a dermatologist, or pathologist who has additional training in making diagnoses from skin samples and may be more experienced with certain skin cancers than a general pathologist. He or she will determine if the cells appear dysplastic, that is, abnormal or may become cancerous.

Incisional and excisional biopsies

An incisional biopsy removes only a portion of the tumor. Removal of the entire tumor is called an excisional biopsy. A small piece of skin is removed for further examination, and the edges of the wound are sewn together. Both types of biopsies can be done using local anesthesia. Excisional biopsy is the method usually preferred when melanoma is suspected. Only a narrow rim of normal skin should be taken with this biopsy.

Punch biopsy

A punch biopsy removes a small sample of skin. The doctor uses a punch biopsy tool that looks like a tiny, round cookie cutter. Once the skin is numbed with a local anesthetic, the doctor rotates the punch biopsy tool on the surface of the skin until it cuts through all the layers of the skin, including the epidermis, dermis, and the upper parts of the subcutis. It may be appropriate for areas such as the palm, sole, digit, face ear, or for very large lesions.

Shave biopsy

After numbing the area with a local anesthetic, the doctor “shaves” off the top layers of the skin (the epidermis and part of the dermis) with a surgical blade. A shave biopsy is useful in diagnosing many types of skin diseases and in treating benign (noncancerous) moles. However, if an invasive melanoma is suspected, a shave biopsy sample may not be deep enough to precisely measure its thickness or depth of invasion. If melanoma is suspected, a shave biopsy is usually not done.

Blood Tests

There are no specific blood tests for melanoma, but sometimes a blood LDH level might be helpful. LDH (lactate dehydrogenase) is an enzyme found in the blood that may be elevated when a lot of cancer cells are present or when the liver has been damaged by cancer. Blood LDH levels can be a marker for widespread melanoma. It is seldom elevated at the time of initial diagnosis.

Imaging Studies

Chest x-ray

A chest x-ray may be taken to determine whether the melanoma has spread (metastasized) to the lungs. A chest x-ray is sometimes not needed for patients with very early (thin) melanoma.

Imaging methods such as computed tomography (CT) scans, magnetic resonance imaging (MRI) scans and positron emission tomography (PET) may be used to see whether the melanoma has spread to other organs or to lymph nodes deep inside the body. These tests may not always be needed and are used mostly for patient with known or suspected metastases.

Computed tomography (CT)

The CT scan is an x-ray procedure that produces detailed cross-sectional images of your body. Instead of taking one picture, as does a usual chest x-ray, a CT scanner takes many pictures as it rotates around you. A computer then combines these pictures into an image of a slice of your body. The machine produces multiple images of the part of your body that is being studied.

Often after the first set of pictures is taken, you will receive an intravenous injection of a special dye that helps better outline structures in your body. A second set of pictures is then taken. Some people get hives or, rarely, more serious allergic reactions like trouble breathing and low blood pressure can occur. Be sure to tell the doctor if you have ever had a reaction to any contrast material used for x-rays. The CT may detect melanoma if it has spread to your lungs or liver and can help find enlarged lymph nodes that might contain cancer.

Magnetic resonance imaging (MRI):

MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed and then released in a pattern formed by the type of tissue and by certain diseases. A computer translates the pattern of radio waves given off by the tissues into very detailed cross-sectional images of parts of the body. A contrast material might be injected just as with CT scans. MRI can be very useful for looking for tumors in the brain and spinal cord.

Positron emission tomography:

Positron emission tomography (PET) uses glucose (a form of sugar) that contains a radio­active atom. Cancer cells of the body absorb large amounts of the radioactive sugar because of their high rate of metabolism. The substance is injected into a vein, and a special camera can detect the radioactivity in the body. PET may supplement the results of the CT and MRI examinations.

Note: In general, all these scans with radio­active compounds are easy to take. There are usually no side effects, and you are exposed to only a tiny amount of radioactive substance.

Procedures and Tests to Detect Metastases

Sentinel lymph node mapping and biopsy:

This has become a standard procedure for finding the lymph nodes that drain lymph fluid from the area of the skin where the melanoma developed. If the melanoma has spread, these lymph nodes are usually the first place it will go. That is why these lymph nodes are called sentinel nodes (sentinel means to watch over the tumor, so to speak). These lymph nodes are then checked by a pathologist for any spread of melanoma. It is done to help determine a patient’s risk of recurrence and to help guide treatment decisions.

To map the sentinel lymph node, some time before surgery the doctor injects a small amount of radioactive material into the melanoma. By checking various lymph node areas with a radioactivity detection device like a Geiger counter, the doctor can see what group of lymph nodes your melanoma is most likely to travel to in order to find the sentinel lymph node. Then the doctor injects a small amount of a harmless blue dye and radioactive chemical into the site of the melanoma. After about an hour, a surgeon makes a small incision in the identified lymph node area. The lymph nodes can then be checked to find which one has turned blue or become radioactive. When the appropriate sentinel node has been found, it will be removed for microscopic examination. If melanoma cells are found in this lymph node, the remaining lymph nodes in this area are surgically removed. If the sentinel node does not contain melanoma cells, no more lymph node surgery is needed.

If a lymph node near a melanoma is abnormally large, an FNA or surgical biopsy of that lymph node is done and the sentinel node procedure may not be needed.

Fine needle aspiration biopsy

A fine needle aspiration (FNA) biopsy uses a syringe with a very thin needle to remove cells from a mass. A local anesthetic is sometimes used to numb the area. This test rarely causes much discomfort and does not leave a scar. FNA may be used to biopsy enlarged lymph nodes near a melanoma to find out if the cancer has metastasized (spread). Some­times the doctor can view a CT scan (a special type of x-ray) or ultrasound to guide the needle into a mass.

Surgical (excisional) lymph node biopsy:

In this procedure, an abnormally large lymph node is removed surgically through a small skin incision. Local anesthetic is generally used. This technique is often done if a lymph node’s size suggests spread of melanoma, but the FNA did not find any melanoma cells.

Diagnosis of Metastatic Melanoma

Although many melanomas are completely cured, some melanomas spread so quickly that a patient can have spread of melanoma to the lymph nodes, lungs, brain, gastrointestinal tract, or liver while the original melanoma is still small. On the other hand, melanoma that has spread to other parts of the body may not be found until long after the original melanoma was removed from the skin.

When such spread has occurred, the metastatic melanoma in certain organs might be confused with a cancer starting in that organ. For example, melanoma that has spread to the lungs might be confused with a primary lung cancer (cancer that starts in the lungs). Special tests can be done on biopsy samples to tell whether it is a melanoma or some other kind of cancer. This is important because different cancers are treated differently.

Examination of the Skin Biopsy

It is important to measure the thickness of a melanoma under a microscope because this is believed to be one of the best ways to determine the prognosis (or outlook for survival).

The pathologist examining the skin biopsy specimen measures the thickness of the melanoma under the microscope with a device called a micrometer, which is like a small ruler. This technique is called the Breslow measurement. The thinner the melanoma, the better the prognosis. In general, melanomas less than 1 millimeter (mm) in depth (about 1/25 of an inch or the diameter of a period or a comma) have a very small chance of spreading. As the melanoma becomes thicker, it has a greater chance of spreading. The thickness of the melanoma also guides the choice of treatment.

Another system describes the thickness of a melanoma in relation to its penetration into the skin instead of actually measuring it. The Clark level of a melanoma uses a scale of I to V to describe thickness (with higher numbers indicating a deeper melanoma): (The Clark level Roman numerals should not be confused with the stage grouping Roman numerals.)

• if the melanoma stays in the epidermis (Clark level I)
• if the melanoma has begun to penetrate to the upper dermis (Clark level II)
• if the melanoma involves most of the upper dermis (Clark level III)
• if the melanoma has penetrated to the lower dermis (Clark level IV)
• if the melanoma has penetrated very deeply, to the subcutis (Clark level V)

In the newest classification, the Breslow measurement of thickness has become more important than the Clark level of penetration as the first prognostic factor. This is because the thickness measurement is easier and depends less on the pathologist’s judgment. Sometimes, however, the Clark level tells us that a melanoma is more advanced than we may think it is from the Breslow measurement. Therefore, both systems are often used to help stage a melanoma.

In either system, the melanoma has a worse prognosis if the pathologist says it is ulcerated (covering layer of epidermis is absent).

INTRODUCTION

STAGES OF MELANOMA

For more information on these treatment guidelines, or on cancer in general, call the NCCN at 1-888-909-NCCN or the American Cancer Society at 1-800-ACS-2345. Or you can visit these organizations’ web sites at www.cancer.org (ACS) and www.nccn.org (NCCN).

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