MALIGNANT NEOPLASMS

Fibrosarcoma

Fibrosarcoma is a malignant neoplasm of fibrous connective tissue that can also arise in bone and which is rare in the head and neck region. It generally affects the sexes equally with the highest incidence in patients between 20 and 40 years of age. Cases in infants and young children are known to occur. Fibrosarcoma has an uncontrolled rapid or slow growth and when in the oral cavity it is generally associetad to mobility of teeth, and bone destruction. When the gingiva is affected it is generally a painless, sessile swelling that may ulcerate. Pain will arise with involvement of nerve terminals. Fibrosarcoma does not have a marked tendency to metastasize.

Any intraoral growth showing malignant characteristics could be included in the differential diagnosis. A spectrum of low grade fibrosarcomas with a relatively benign course (dermatofibroma protuberans), difficult to differentiate from reactive fibroses of various kinds (desmoid tumor), has been rarely reported in oral soft tissues. Biopsy will show the nature of the lesion. Radical surgery is the treatment of choice. Radiation therapy seems to have no effect on this neoplasm.

Figure 26. This exophytic lesion had a history of a moderate slow growth of several months. Two molars in the area were lost due to extreme mobility. The tumor involved alveolar ridge, buccal gingiva and buccal mucosa. A bone sequestrum is evident. Biopsy showed this neoplasm to be a fibrosarcoma.

Melanoma

Malignant melanoma (MM) is the third most frequent malignant neoplasm of the skin. Primary intraoral malignant melanoma (OMM) is a rare neoplasm which represents between 2 to 5 percent of all melanomas in humans. It occurs more often in Japanese, Africans and less frequently in Caucasians. Cutaneous and mucosal melanomas result from malignant proliferation of melanocytes which originate in the embryonal neural crest.

The mortality rate of cutaneous MM in most European countries increases 3 to 5% annually. Male mortality exceeds female mortality. In Northern Europe the mortality rate is 4 to 6 times higher than in Mediterranean countries, including Greece and Portugal. Statistical studies have shown good evidence that the increase in the incidence of cutaneous MM is a result of intermittent recreational sun exposure. This is not the case for OMM because the majority of them occur in the palate and maxillary gingiva, and less frequently in the buccal mucosa, mandibular gingiva, lips, tongue and floor of the mouth. Intraoral melanocytic nevi are also more common in the palate. One third of all melanomas may be unpigmented but in the oral cavity only 5% are non-pigmented.

According to several comprehensive reports and reviews of the literature during the last 10 years, slightly more than 80% of patients with OMM are over 40 years of age, which is 10 years later than cutaneous melanomas. Around 55% of patients with OMM are males while there is a prevalence of females for cutaneous melanoma. Treatment of choice is surgery followed by radiation. The role of elective neck dissection is unclear because the status of the regional lymph nodes does not appear to affect survival. Dissection of neck nodes is probably not warranted. Chemotherapy is reserved for patients with systemic disease. Immunotherapy in patients with mucosal melanomas has in general not improved survival or local-regional control rates.

The 5 year survival rate for OMM has been estimated between 10 and 20% as opposed to 75% for cutaneous melanomas. Average time of first local recurrence for OMM has been reported to be 9 to 12 months and metastases are diagnosed within 3 months after recurrence. Average survival rate after metastasis is 6 months.

Figure 27. This is an example of gingival melanoma. Note the multiple foci of this malignant neoplasm. Melanomas bleed easily and grow very rapidly. This 50 year-old male had several metastases to his cervical lymph nodes. Some intraoral melanomas can be amelanotic in which case the diagnosis is not as obvious as here.