Hyperpigmented lesions in mouth or nose indicate an aggressive type of melanoma

Researchers say dentists and ear, nose and throat specialists should be vigilant and refer patients with suspected lesions to a specialized center (image: Wikimedia Commons)

A review of clinical and pathological data for 51 patients diagnosed with the disease and treated at A.C. Camargo Cancer Center in São Paulo, Brazil, between 1954 and 2012 showed a clear association between late diagnosis and shorter survival.

According to the results, which were published in the International Journal of Oral & Maxillofacial Surgery, most of the patients presented with the disease at an advanced stage at the time of diagnosis, and at the last clinical evaluation only ten were alive.

The study was led by Mauro Kasuo Ikeda, a head and neck surgeon affiliated with A.C. Camargo Cancer Center’s National Institute of Science & Technology in Oncogenomics (INCITO) in São Paulo State. INCITO is one of the National Science & Technology Institutes (INCTs) funded by the National Council for Scientific & Technological Development (CNPq) and supported by FAPESP.

“The main problem is the difficulty of diagnosing mucosal melanoma because it’s rare and not always visible. Many patients are already at an advanced stage when they come to a specialized service,” Ikeda said.

According to Ikeda, eight out of every ten cases of mucosal melanoma are identified by pigmentation in areas such as the upper gingiva (gums) and nasal cavity. The first person to notice these tumors is typically a dentist or an ear, nose and throat specialist.

However, when patients are referred to a specialized center, more than half already exhibit ulcerated lesions that require more aggressive surgical treatment, offering less possibility of controlling the disease.

Survival rates have not improved significantly over the years, according to Ikeda, because treatment for this type of cancer has remained essentially surgical since the 1950s.

“These lesions don’t respond well to chemotherapy or radiotherapy,” he said. “The difference is that the worst cases were once inoperable but can now be treated by surgery, thanks to advances in plastic reconstruction techniques.”

According to Ikeda, malignant tumors are classified into stages, typically from 0 through 4, depending on how large they are and how fast they are likely to spread. In the case of mucosal melanoma, however, practically all the lesions diagnosed are considered stage 3 or 4, regardless of their size or depth. This indicates a poor prognosis with a high risk of metastasis and death relating to the tumor. Early diagnosis (stages 0-2) is as rare as the disease itself.

“But early diagnosis isn’t impossible,” Ikeda said. “The study showed that 84.3% presented with strong pigmentation in the oral and nasal cavities. When dentists and ear, nose and throat specialists know this, they can look for lesions that might be present in these areas and can refer patients to a specialized center if they identify any incipient lesions.”

Caution is required with patients around age 40 or more, many of whom have mercury-containing amalgam tooth fillings. “When dentists performed this procedure, a fragment of mercury often escaped into the oral mucosa, producing darker pigmentation with no relation to cancer. So diagnosis can be confusing and requires a well-trained professional,” Ikeda said.

Lesions in the paranasal sinuses are practically impossible to see, according to Ikeda, and are usually diagnosed when a patient presents with symptoms such as nasal bleeding or when a tumor has spread to other parts of the head.

Risk factors and markers of aggressiveness

Unlike other head and neck tumors, mucosal melanoma is not associated with alcohol or tobacco consumption. Nor is there a link to prolonged exposure to solar radiation, as with skin melanoma.

“Some research has detected mutations in individual tumors, but these are sporadic findings rather than a factor that can be recognized as a cause. There isn’t a well-established cause,” Ikeda said.

Currently, the researchers at INCITO are endeavoring to identify clinical aspects and molecular biomarkers that can be used as prognostic predictors and thus help improve survival rates.

“There are also better prospects for treatment thanks to new chemotherapy and immunotherapy drugs,” Ikeda said. “Monoclonal antibodies may impact the evolution of these patients.”

The article “Head and neck mucosal melanoma: clinicopathological analysis of 51 cases treated in a single cancer centre and review of the literature” (doi: 10.1016/j.ijom.2015.08.987) can be read at www.sciencedirect.com/science/article/pii/S0901502715012990.