Through the looking glass: The oncology patient

April 1, 2007

Cutaneous metastasis from an internal malignancy is estimated to occur in 1 percent to 9 percent of patients with cancer.

Washington - It has been said that the skin is the window to the inside of the human body, and patients with internal malignancies may present with cutaneous manifestations that should serve as a red flag to the wary physician.

One specialist, speaking here at the 65th Annual Meeting of the American Academy of Dermatology, reviewed cutaneous disease and its association with internal malignancy.

Cutaneous metastasis

These metastases often occur on a cutaneous surface near the site of the primary tumor.

"Most cutaneous metastases are firm dermal or subcutaneous nodules that may ulcerate, and may present as single or multiple lesions," says Steven R. Mays, M.D., associate professor of dermatology at the MD Anderson Cancer Center and the University of Texas Medical School, Houston.

Dr. Mays cites a study that showed that 10 percent of all patients with metastatic malignancies had cutaneous metastases. Also, cutaneous metastasis was the first sign of extranodal metastatic disease in 8 percent of this population.

He tells Dermatology Times that breast cancer has a high propensity for metastasizing to the skin and represents the most common type of cutaneous metastasis in the United States. These metastases are usually nodular and remain local, but remote involvement is possible and often favors the scalp. Inflammatory metastatic breast is the second most common type of cutaneous breast metastasis. Here, Dr. Mays says the differential diagnosis would include a localized bacterial cellulitis of the chest wall.

Malignant melanoma is another common type of metastasis. Melanoma cutaneous metastases may be melanotic or amelanotic and can appear as nodules, plaques, clustered papules, subcutaneous induration or in a zosteriform pattern. Recent data show that 45 percent of patients with metastatic melanoma had skin metastases.

Dr. Mays says that lung and colorectal cancers have a low overall propensity for metastasizing to the skin, yet these two malignancies are still a common cause of cutaneous metastasis, simply because they are very common malignancies.

Dermatomyositis (DM)

Dr. Mays says that most dermatologists diagnose dermatomyositis based on the presence of classic cutaneous findings, proximal muscle weakness and elevated muscle-derived enzymes.

The clinical onset of DM may herald an internal malignancy. Approximately 20 percent to 30 percent of adult patients with dermatomyositis have a malignancy concurrent with (or subsequent to) the diagnosis of DM.

"In Caucasians, the most common associated malignancies are ovarian, lung, pancreatic, gastric, colorectal and non-Hodgkin's lymphoma. In patients in Asian countries, the most common associated malignancy is nasopharyngeal carcinoma," Dr. Mays says.

Dr. Mays cites a population study that analyzed the frequency of specific cancer types in dermatomyositis. The results showed that the risk of cancer is highest within the first year of diagnosis of DM. The risk of ovarian, pancreatic, colon and lung cancers remains elevated for at least five years after the diagnosis of DM. Therefore adult patients with dermatomyositis should be periodically re-screened for internal malignancies for a few years following the diagnosis of DM.

Dr. Mays says that just as DM may spontaneously improve following successful treatment of the patient's malignancy, the recurrence of DM may herald a relapse of the original malignancy. In the latter situation, he suggests that the physician consider workup for a new (second) malignancy.

Fungal infections

Superficial infections of the skin by dermatophytes and Candida are common in the immunosuppressed (IS) host.

These bugs' clinical presentation is similar to that in the immunocompetent host. Superficial skin infections by Candida and dermatophytes generally do not cause disseminated disease, even in the most immunosuppressed host.

"Oral candidiasis, however, in the IS host may precede esophageal candidiasis, which may in turn cause candidemia. This is the rationale for thrush prophylaxis in the IS population," Dr. Mays says.