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.

* These are malignant neoplasms, but they sometimes have the clinical & historical features of benign neoplasms.

* 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.