Dermatologists urged to keep sharp eye out for rare tumor types

Harrison Hot Springs, British Columbia - There are some skin tumors that are so rare that dermatologists might never encounter them after studying them in medical school. Then again, they might - and dermatologists should know what to look for and how to treat them, because some are deadly.

Darrell J. Fader, M.D., clinical assistant professor of dermatology at the University of Washington, addressed the topic in his presentation, "Unusual Skin Tumors," at the Pacific Northwest Dermatological Conference here.

"These unusual tumors are ones that we as dermatologists should keep in mind as we treat our patients," says Dr. Fader, who has a private practice in Seattle and Bellevue, Wash. "They occur rarely and often are difficult to detect before pathology, but we need to remember that they do occur and that once identified, they are best approached in a multi-dimensional manner involving other specialists."

Merkel cell carcinoma

"Merkel cell carcinoma is very rare - probably only about 1,000 total cases have been reported in the literature," he says. "This condition usually appears in senior citizens 65 years old and above, and usually presents as a single nodule that's shiny and reddish-blue in color. Clinically, they mimic standard skin cancers - they're difficult to differentiate from more common ones and usually are diagnosed only during pathology."

Dr. Fader says about half of Merkel cell carcinoma occurs on the head and neck, and the majority of the rest of the cases on the arms and legs.

"This is a more serious tumor than standard skin cancers," he says. "Merkel cell carcinoma is thought to derive from neuroendocrine origin and is possibly exacerbated by sun exposure."

One-third to one-half of patients who undergo excision of Merkel cell carcinoma tumors will have a recurrence within a year, Dr. Fader says. One-half to two-thirds of Merkel cell carcinoma patients will develop regional metastasis - invasion of adjacent skin and/or lymph nodes - within one-and-a-half years. In about a third of these patients, the cancer will invade the blood and spread to other organs.

Treatment involves wide local excision or Mohs surgery, which Dr. Fader says is being increasingly used. He says consultation with a radiation oncologist is important for adjuvant treatment, and that a surgical oncologist may be consulted to consider lymph-node removal. In tumors that spread regionally, treatment involves lymph-node removal and radiation therapy; if tumors spread internally, there are a variety of chemotherapy options with a medical oncologist involved.

"With the more systemic disease, good results can occur initially, but the carcinoma is likely to recur within a year to a year-and-a-half in half to two-thirds of victims," Dr. Fader tells Dermatology Times. "This is a very tough disease."

Angiosarcoma

An even tougher disease is angiosarcoma, another very rare skin disease that also occurs mostly among older people.

"These tumors present on the neck and head - particularly the scalp - in about half the cases," Dr. Fader says. "Non-head-and-neck angiosarcoma is sometimes associated with lymphedema, a swelling of the extremities where these tumors also occur. Clinically, angiosarcoma presents as ill-defined plaques that progress to nodules, which may become infected and bleed."

He adds the tumors' presentations can vary from flat patches or larger nodules to bruise-like in appearance. This may make it harder to diagnose than Merkel cell carcinoma because angiosarcoma mimics many more kinds of skin disorders.

"Unfortunately, the clinical course of this disease is rapid progression, and it usually spreads internally," Dr. Fader says. "Five-year survival happens in less than 20 percent of cases; median survival is one to two years."