Soft tissue tumors are characterized by being persistent and progressive; they do not resolve without treatment. They are usually not painful early in their development, and the growth rate varies from weeks to years.
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. Malignant neoplasms are more rapidly growing, with growth rate measured in weeks to months. 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 others are surrounded by a fibrous connective tissue capsule, which may allow them to be moved within the tissue independent of surrounding structures (freely-movable). If located in the area of teeth, benign tumors are more likely to move teeth, while malignant lesions loosen teeth. It is important to note that occasionally malignant lesions, especially of salivary gland origin, have clinical features that are deceptively benign.