Malignant
Tumors of Oral Cavity and Oropharynx
Squamous cell carcinoma (SCC), an epidermoid
cancer, is the most common malignancy in the oral cavity and oropharynx. It
arises from the epithelial lining of the oral cavity in order of decreasing
frequency in the lips, tongue, floor of the mouth, gingiva, and palate. In the
oropharynx, it arises most often from the palatine tonsillar crypts. Although
there are similarities in squamous cell carcinogenesis in the oral cavity and
oropharynx, significant clinical and biologic differences also exist,
suggesting that SCCs in the two regions are two separate disease entities. Both
oral cavity and oropharyngeal cancers have a male predominance, and both are
rarely seen before the age of 50. A striking difference between the two
malignant processes is the declining incidence of SCC in the oral cavity and
the rising incidence of it in the oropharynx. Tobacco is the most significant
risk factor for the development of oral cavity SCC. Alcohol has a synergistic
effect with tobacco as a carcinogen in this process. Betel nut chewing,
radiation exposure, vitamin deficiencies, and environmental and occupational
exposures are atypical risk factors in the development of SCC. Although tobacco
remains a risk factor for the development of oropharyngeal cancer, human
papillomavirus infection, specifically with serotype 16, is likely the most
important causative agent in the development of SCC of the oropharynx.
Oral cavity cancer typically
begins with a malignant precursor of leukoplakia or erythroplakia. In
leukoplakic lesions, the tendency toward malignant growth is high if the cells
of the prickle cell layer show disorientation with dyskeratosis. Fissuring and
papillomatous formation are clinical danger signs during the transformation
process of the premalignant lesion. In contrast, a precursor lesion is not
typically seen with oropharyngeal SCC. Dysphagia, odynophagia, otalgia, and
weight loss are clinical presentations shared by both oral and oropharyngeal SCC.
Dentition problems and oral bleeding are typical of oral SCC, and obstructive
sleep apnea and the presence of a neck mass are frequent findings in
oropharyngeal SCC. The gross appearance of SCC varies from grayish white,
nondescript, thickened mucosa consistent with its precursor leukoplakia to
large flat, ulcerated lesions or bulky fungating masses with or without local
invasion. Dysplastic epithelial changes occur early in the disease course.
Basement membrane compromise is indicative of invasive disease, allowing for
perineural and lymphovascular invasion. Histologically, most oral SCC lesions
demonstrate squamous differentiation, with nests of cells with pink cytoplasm,
intercellular bridges, and keratin pearls with a desmoplastic stroma.
Oropharyngeal SCC demonstrates “blue cell” morphology with scant cytoplasm and
hyperchromatic nuclei with high mitotic activity and little to no
keratinization. Regional or cervical lymph node spread is frequently seen with
oropharyngeal SCC and much less often with oral SCC. In tumors associated with
human papillomavirus infection, the overall prognosis is much better for
oropharyngeal SCC than for oral SCC. Treatment for both diseases includes a
“cocktail” of irradiation and chemoirradiation and/or surgical resection.
Luetic glossitis, considered a premalignant lesion, is an
oral manifestation of syphilis, which presents as diffuse lingual atrophy with
a loss of papillae. Kaposi sarcoma is an endothelial malignancy seen in
the oral cavity, primarily in patients with AIDS. Rarely, it can be found in
older men of eastern European or Mediterranean descent; in patients from
endemic areas of Africa, specifically Bantu children from South Africa; and in
immunosuppressed individuals, particularly transplant recipients. The clinical
subtypes differ according to the epidemiologic group affected. The most common
site in the oral cavity is the palate, followed by the gingiva and dorsal
surface of the tongue. The appearance of the lesion depends on the point in
time that it is seen during the disease course. Early lesions are flat, red,
and asymptomatic, and late lesions are larger, darker, and raised, with
ultimate progression to large nodular lesions that ulcerate, bleed, and are
painful. The incidence of this lesion has decreased dramatically with the
widespread use of highly active antiretroviral therapy (HAART).
Lymphosarcoma, as well as other varieties of lympho-
blastomas, may be observed occasionally in the oral cavity. The tumor
originates from lymphoid tissue in the submucosa, especially the palate and
pharynx. Typical features of this type of tumor are rapid growth and early
local and regional lymph node metastases.
