Benign and Malignant Tumors
If a soft tissue enlargement appears to be a tumor, the clinician must next determine if the enlargement is benign or malignant. Benign tumors are typically better defined or circumscribed and have a slower growth rate, measured in months and years, than malignant neoplasms. Malignant neoplasms are more likely to be painful and cause ulceration of the overlying epithelium than benign lesions. Since malignant neoplasms invade or infiltrate surrounding muscle, nerve, blood vessels, and connective tissue, they are fixed or adherent to surrounding structures during palpation. Some benign tumors are also fixed to surrounding structures, but other benign tumors are surrounded by a fibrous connective tissue capsule, which may allow the lesion to be moved within the tissue independent of surrounding structures.
Benign tumors can be subdivided into four categories: epithelial, mesenchymal, salivary gland tumors, and cysts of soft tissue. Although soft tissue cysts are not tumors, their historical and clinical features resemble those of benign tumors. Each of these categories is further subclassified as shown in Tables 5-8.
Table 5. Benign Epithelial Tumors.
|BENIGN EPITHELIAL TUMORS|
Firm; non-tender; fixed to the surface; rough or cauliflower surface; pale.
|Verruca vulgaris||Broad-based; exophytic|
|Condyloma acuminatum||Broad-based; exophytic; multiple lesions; frequently genital lesions|
Table 6. Benign Mesenchymal Tumors.
|BENIGN MESENCHYMAL TUMORS|
Overlying mucosa is normal unless traumatized; usually well-circumscribed, asymptomatic, slowly growing
|Irritation fibroma||Firm or compressible|
|Epulis fissuratum (inflammatory fibrous hyperplasia)||Located adjacent to flange of removable denture; firm or compressible|
|Peripheral ossifying fibroma||Occursonly on gingiva; firm; sometimes ulcerated; sometimes vascular; may move teeth|
|Leiomyoma||Firm; sometimes vascular.|
|Rhabdomyoma||Firm; located in areas of skeletal muscle|
|Peripheral giant cell granuloma||Occurs only on gingiva or attached alveolar mucosa; vascular|
|Hemangioma||Congenital; compressible; vascular; circumscribed or diffuse|
|Lymphangioma||Congenital; compressible; usually diffuse; not vascular|
|Pyogenic granuloma||Vascular; compressible; frequently has rapid growth, ulcerated, bleeds easily|
|Lipoma||Encapsulated; compressible; sometimes yellow|
|Neuroma (traumatic or amputation neuroma)||Firm; usually tender to palpation; size of lesion is dependent upon size of involved nerve|
|Neurofibroma||Firm or compressible; non-tender; circumscribed or diffuse; may occur with neurofibromatosis|
|Schwannoma (neurilemoma)||Encapsulated; firm; non-tender;|
|Granular cell tumor||Firm; sometimes overlying surface is rough|
|Congenital epulis||Firm; congenital; occurs only on attached alveolar mucosa|
Table 7. Benign Salivary Gland Tumors.
|BENIGN SALIVARY GLAND TUMORS|
Well-circumscribed; slowly growing; asymptomatic; overlying mucosa is normal unless traumatized; occur only where salivary glands are present (everywhere in the oral mucosa except midline and anterior hard palate, gingiva and attached alveolar mucosa).
|Pleomorphic adenoma (Mixed tumor)||Encapsulated; firm or compressible|
|Monomorphic adenoma||Encapsulated; firm or compressible|
|Oncocytoma||Encapsulated; firm; occurs in older adults|
|Papillary cystadenoma lymphomatosum|
|Encapsulated; firm or compressible; occurs in parotid gland|
|Adenoid cystic carcinoma*||Firm|
|Acinic cell carcinoma*||Firm|
|Mucoepidermoid carcinoma, low-grade*||Compressible or fluctuant|
|Polymorphous low-grade adenocarcinoma*||Firm|
* These are malignant neoplasms, but they sometimes have the clinical & historical features of benign neoplasms.
Table 8. Soft Tissue Cysts.
|SOFT TISSUE CYSTS|
Compressible; well-circumscribed; asymptomatic; slowly growing; overlying mucosa is normal.
|Gingival cyst||Located on attached gingiva anterior to 1st molars|
|Lymphoepithelial cyst||Usually has yellow color; occurs in floor of mouth, ventral & lateral surfaces of tongue, soft palate & tonsillar area; also occurs in anterior cervical lymph node chain (branchial cleft or cervical lymphoepithelial cyst)|
|Epidermoid or dermoid cyst||“Doughy” to palpation; usually occurs in floor of mouth; occurs commonly in skin|
|Thyroglossal tract cyst||Occurs in midline of neck; may be attached to hyoid bone & moves when patient swallows|
|Nasolabial cyst||Located in maxillary labial fold & ala of nose area|
* These are cysts, but they have the clinical & historical features of benign neoplasms.
It should be emphasized that the clinical descriptions above are general guidelines, and exceptions occur. Removal of the lesion and microscopic examination of the tissue is the only way to arrive at a definitive diagnosis.