History
In most cases, cutaneous metastases develop after the initial diagnosis of the primary malignancy (eg, metastases of breast carcinoma involving the chest wall several years after a mastectomy). In a very small percentage of patients, metastases may be discovered at the same time or prior to the diagnosis of a primary tumor (eg, lung and renal cell carcinoma presenting as scalp metastases in a man who otherwise appears well and gives no history of prior malignancy).
Patients may present with rapidly developing nodules or tumors. Although asymptomatic in most instances, pain and tenderness may be noted. Any rapidly developing or eruptive lesions should warrant careful consideration of the possibility of metastasis.
Physical Examination
Most cutaneous metastases occur in a body region near the primary tumor. The most common presentation of cutaneous metastases is nodules. The nodules are often nonpainful, round or oval, firm, mobile, and rubbery in texture. The nodules are usually flesh colored, although they may also be other colors (eg, from flesh colored to brown or blue-black).
Often, the nodules from the metastases of renal cell carcinoma and occasionally thyroid carcinoma are red and purple. They vary in size from barely perceptible lesions to large tumors. Multiple nodules appear rapidly before growth slows down.
Breast cancer
Carcinoma may engender a brisk inflammatory response mimicking cellulitis. This pattern is referred to as inflammatory breast carcinoma. When many telangiectatic blood vessels are encountered, the pattern is referred to as carcinoma telangiectodes. Occasionally, the skin may have an orange peel–like appearance (peau d'orange) and/or changes in the local blood flow may occur. In other cases, the skin may feel firm and have a breastplatelike appearance, which is referred to as carcinoma en cuirasse.
Breast cancer is one of the most common malignancies to spread to the skin. The most likely site for cutaneous metastases in women is the chest; less common sites include the scalp, the neck, the upper extremities, the abdomen, and the back.
Occasionally, patients with metastatic breast cancer have a firm, scarlike area in the skin. When this occurs on the scalp, hair may be lost, and the clinical appearance may mimic alopecia areata, except that the skin exhibits marked induration on palpation. This condition, known as alopecia neoplastica, is shown in the images below.
Close-up view of patient with alopecia neoplastica due to metastatic breast cancer shows telangiectases and nodularity. The plaque was markedly indurated on palpation; in contrast, patients with alopecia areata would exhibit normal skin texture.
Lung cancer
The most frequently encountered metastases in men come from lung cancer. The most common site for cutaneous metastases in men is the chest, followed by the abdomen and the back. Other areas (in decreasing order of frequency) include the scalp, neck, face, extremities, and pelvis. For women, the most common areas (in decreasing order of frequency) are the chest, abdomen, back, and upper extremities.
Gastrointestinal cancer
Gastrointestinal cancers (usually colon and stomach cancer) often metastasize to the abdomen and the pelvis. Gastrointestinal carcinomas may spread along the urachus and produce nodules at the umbilicus; those at the umbilicus have been referred to as Sister Mary Joseph nodules. (Sister Mary Joseph was a nurse at the Mayo Clinic who helped to prepare patients prior to operation for gastrointestinal surgery. She noted that the nodules at the umbilicus were an ominous sign of extensive involvement of colorectal carcinoma.)
Malignant melanoma
About 60,000 Americans develop malignant melanoma each year, but only 9000 deaths are attributed to the disease annually in the United States. When malignant melanoma metastasizes, the skin is commonly involved. In men, melanomas are likely to metastasize to the chest, extremities, and back. A large portion of female patients have metastases to the lower extremities. Recent reviews indicate that the proportion of metastases due to melanoma is increasing. This finding is not unexpected as the incidence of melanoma continues to rise. [7]
Metastases of melanoma may simulate blue nevi and may be epidermotropic or simulate primary cutaneous melanoma. A zosteriform appearance reportedly is rare. [10]
Other cancers
Cutaneous metastases from squamous cell carcinoma in the oral cavity usually remain in the local area, most often affecting the neck and face.
Renal cell carcinoma may metastasize to the scalp, operative scars, or many other surfaces. Because of the prominent vascular supply of renal cell carcinoma, lesions may mimic a hemangioma or a pyogenic granuloma.
Metastases from the ovary and the uterus are seen in the skin of the lower abdomen, the groin, or the upper thigh.
Summary
Common cutaneous metastasis sites and their probable primary sites are as follows:
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Metastasis to scalp - Breast, lung, kidney
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Metastasis to neck - Oral squamous cell carcinoma
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Metastasis to face - Oral squamous cell carcinoma, renal cell, lung
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Metastasis to extremities - Malignant melanoma, breast, lung, renal, intestinal
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Metastasis to chest - Breast, lung, malignant melanoma
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Metastasis to abdomen - Colon, lung, stomach, breast, ovary
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Metastasis to umbilicus - Stomach, pancreas, colon, ovary, kidney, breast
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Metastasis to pelvis - Colon
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Metastasis to back - Lung
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Low-power view of breast cancer metastasis with surrounding fibrosis.
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Breast cancer metastasis with hyperchromatic cells extending between thickened collagen bundles. Dilated lymphatics are noted.
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Alopecia neoplastica due to metastatic breast cancer.
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Close-up view of patient with alopecia neoplastica due to metastatic breast cancer shows telangiectases and nodularity. The plaque was markedly indurated on palpation; in contrast, patients with alopecia areata would exhibit normal skin texture.
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Breast cancer with an Indian file pattern of metastasis.
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A well-circumscribed metastasis of renal cell carcinoma is surrounded by compressed collagen, which is indicative of rapid growth.
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Pleomorphic clear cells with prominent vasculature are characteristic of metastatic renal cell carcinoma.
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Metastatic squamous cell cancer typically does not involve the epidermis, allowing for differentiation of metastases from primary cutaneous squamous cell cancer.
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Biopsy of metastatic melanoma reveals a well-circumscribed tumor in the dermis with no connection with the overlying epidermis. Hematoxylin and eosin‒stained sections; original magnification 20x.
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High-powered examination reveals a nest of atypical melanocytes with enlarged and pleomorphic nuclei. Melan-A and S-100 stains were positive and helped confirm the diagnosis. Hematoxylin and eosin‒stained sections; original magnification 200x.
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High-power examination reveals neoplastic epithelioid cells within dilated lymphatics. Hematoxylin and eosin‒stained sections; original magnification, 400x.
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Inflammatory breast carcinoma.
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High-powered microscopic examination reveals tubules composed of clear cells, hemorrhage, and a prominent vascular pattern characteristic of metastatic renal cell carcinoma.
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Biopsy of a nodule on the scalp revealed a precocious metastasis from renal cell carcinoma. Cutaneous metastases are sometimes the first presentation of internal disease. Histologic examination reveals a spherical tumor in the dermis with no connection to the overlying epidermis. Hematoxylin and eosin‒stained sections; original magnification 20x.
