Bone metastasis from malignant melanoma

Malignant melanoma accounts for 4% of all skin cancers, but it causes 79% of skin cancer deaths. Since 1973 the rate of new diagnosis of malignant melanoma has doubled from six per 100,000 to 12 per 100,000. It is estimated that approximately 50,000 patients will be diagnosed with melanoma this year, and approximately 8000 people will die of the disease.

Risk factors for malignant melanoma include the accumulation of three or more of the following: blond hair, a positive family history for cancer, immunosuppressive disorders such as HIV or AIDS, freckling on the upper back, three or more blistering sunburns before age 20 or outdoor summer jobs for more than three teenage years, exposure to arsenic compounds, and multiple nevi or atypical nevi. Individuals with darker skin have a lower risk for malignant melanoma. In these patients there is a higher incidence of subungual melanoma.

Cancers that metastasize to bone are secondary, meaning that they started elsewhere in the body. Most come from cancers that started in the breast, the prostate, the lung, the kidneys, or the thyroid, and a few from the GI tract such as the stomach and pancreas. Malignant melanoma is not a common cause of cancer metastasis to the skeleton. However, when melanoma does metastasize, one of the most common sites is the skeleton. In the literature, there are very few reports of bone metastasis and bone fracture from malignant melanoma, but they do clearly occur. As of the date of this review, the author has never encountered a case of documented metastasis of malignant melanoma to bone, and has never been called to fix a fracture caused by malignant melanoma.

When skeletal metastasis from malignant melanoma occurs, it is a sign of a very serious stage of the disease. Melanoma is given four stages by the American Joint Committee on Cancer, stage I is Breslow depth of less than 2.01 mm and no ulceration, stage II is Breslow depth of greater than 2.0 mm or lesions at 1.01 - 2.0 mm in depth with ulceration, stage III is regional lymph node metastasis, and stage
IV is distant metastasis, including metastasis to bone.

In patients who die of disseminated malignant melanoma and undergo autopsy, 25 to 50% have metastasis to bone. However, it is the author's opinion that a much smaller number of patients will are alive with metastatice melanoma develop skeletal metastasis that require treatment, such as for pain or for pathologic fracture. It has been found that 80% of bony lesions from malignant melanoma are located in the axial skeleton, the spine, ribs, pelvis, and skull. In summary, the most frequent location of skeletal metastasis on malignant melanoma appears to be the spinal column and the ribs.

Malignant melanoma is one of the most common malignancies of the foot, and it has been reported to metastasize to the adjacent bones in the foot, perhaps by contiguous spread rather then true metastasis. In a similar fashion, subungual (under the fingernail or toenail) melanoma in the hand or the foot has been reported to spread to the adjacent bones of the finger or toe.

Clinical manifestations of bone metastasis from malignant melanoma are severe, sometimes intractable pain, and occasionally systemic manifestations such as fever. The cancer causes lytic lesions in the affected bones, with involvement of the bone marrow. The lesions can be detected with plain radiographs or bone scans.

Treatment of metastatic malignant melanoma in the skeleton is focused on orthopedic stabilization of the affected bone and pain control. Prevention or treatment of pathological fracture is clearly indicated, and the reader should refer to the pages in this web site for an in-depth discussion of that subject. Additional treatment such as chemotherapy and radiation is given based on protocols that continue to evolve.

The mean survival rate for patients with skeletal metastasis of malignant melanoma ranges from 3.64.7 months. One author found that metastasis to the appendicular skeleton was associated with any longer life expectancy than metastasis to the axial skeleton. It is possible that survival can be enhanced with aggressive treatment of appendicular skeletal metastasis.

2/5/2004 HD





831 Beacon Street #130

Newton Center, Massachusetts 02459