Melanoma

Melanoma History Epidemiology & Causes Genetics Symptoms and signs Prevention Diagnosis Types of primary melanoma Prognostic factors Treatment Complications Future thought

Diagnosis

Moles that are irregular in color or shape are suspicious of a malignant or a premalignant melanoma. Following a visual examination and a dermatoscopic exam, used routinely by one in 4 dermatologists in the United States, or an examination using other in vivo diagnostic tools, such as a confocal microscope, the doctor may biopsy the suspicious mole. If it is malignant, the mole and an area around it needs excision.

The diagnosis of melanoma requires experience, as early stages may look identical to harmless moles or not have any color at all. A skin biopsy performed under local anesthesia is often required to assist in making or confirming the diagnosis and in defining the severity of the melanoma. Amelanotic melanomas and melanomas arising in fair skinned individuals (see the "Little Red Riding Hood" sign) are very difficult to detect as they fail to show many of the characteristics in the ABCD rule, and breaks the "Ugly Duckling" sign. These melanomas are often light brown, or pink in color - and very hard to distinguish from acne scarring, insect bites, dermatofibromas, or lentigines. There is no blood test for detecting melanomas.

Excisional skin biopsy is the management of choice; this is where the suspect lesion is totally removed with an adequate (but minimal, usually 1 or 2 mm) ellipse of surrounding skin and tissue. The preferred surgical margin for the initial biopsy should be narrow (1 mm) in order to prevent the disruption of the local lymphatic drainage. The biopsy will include the epidermal, dermal, and subcutaneous layers of the skin, enabling the histopathologist to determine the depth of penetration of the melanoma by microscopic examination. This is described by Clark's level (involvement of skin structures) and Breslow's depth (measured in millimeters). However, for large lesions such as suspected lentigo maligna, or for lesions in surgically difficult areas (face, toes, fingers, eyelids), a small punch biopsy (1.5 to 2 mm) in multiple representative areas will give adequate information and will not disrupt the final staging or depth determination. In no circumstances should the initial biopsy include the final surgical margin (0.5 cm, 1.0cm, or 2 cm), as a misdiagnosis can result in excessive scarring and morbidity from the procedure. Large initial excision will disrupt the local lymphatic drainage and can affect further lymphangiogram directed lymphnode dissection. A small punch biopsy can be utilized at anytime where for logistical and personal reasons a patient will refused more invasive excisional biopsy. Small punch biopsies are minimally invasive and heal quickly, usually without noticeable scarring.

Lactate dehydrogenase (LDH) tests are often used to screen for metastases, although many patients with metastases (even end-stage) have a normal LDH; extraordinarily high LDH often indicates metastatic spread of the disease to the liver. It is common for patients diagnosed with melanoma to have chest X-rays and an LDH test, and in some cases CT, MRI, PET and/or PET/CT scans. Although controversial, sentinel lymph node biopsies and examination of the lymph nodes are also performed in patients to assess spread to the lymph nodes.

Sometimes the skin lesion may bleed, itch, or ulcerate, although this is a very late sign. A slow-healing lesion should be watched closely, as that may be a sign of melanoma. Be aware also that in circumstances that are still poorly understood, melanomas may "regress" or spontaneously become smaller or invisible - however the malignancy is still present. Amelanotic (colorless or flesh-colored) melanomas do not have pigment and may not even be visible. Lentigo maligna, a superficial melanoma confined to the topmost layers of the skin (found primarily in older patients) is often described as a "stain" on the skin. Some patients with metastatic melanoma do not have an obvious detectable primary tumor.