How To Differentiate Soft Tissue Neoplasms

By Francis Rottier, DPM

     Soft tissue neoplasms of the lower extremity present a significant treatment challenge to the treating physician. Although most neoplasms of the lower extremity prove to be benign, the potential for malignancy does exist. The ability to appropriately diagnose and treat soft tissue neoplasms may be the difference between life and death for the patient presenting with a soft tissue tumor of the lower extremity.      Accordingly, let us take a closer look at appropriate evaluation and diagnostic techniques that will aid the physician in making an accurate diagnosis when he or she is presented with a soft tissue neoplasm of the lower extremity.      The soft tissue is defined as nonepithelial, extraskeletal tissue exclusive of the lymphohematopoietic tissue. It includes fibrous connective tissue, adipose tissue, skeletal muscle, blood and lymph vessels, and the peripheral nervous system. Any of these tissues may be the histologic source of a soft tissue neoplasm.      Tumors have traditionally been defined according to their histogenic features. New data suggests that most sarcomas arise from primitive, multipotential mesenchymal cells, which, in the course of neoplastic transformation, differentiate into one or more tissue lines. Clinically, tumors are classified based on location, growth pattern and likelihood of recurrence, the presence and location of metastases, the patient’s age and overall prognosis. Tumors are generally classified as benign or malignant. It is important to understand that many soft tissue tumors are of an intermediate nature. This implies aggressive local behavior and a low to moderate potential to metastasize.      The true incidence of soft tissue neoplasms of the lower extremity is impossible to quantify. Many soft tissue tumors are unreported due to their predominately benign behavior. One study found that benign tumors outnumbered malignant neoplasms by a ratio of 100:1.1 Primary sarcomas presenting below the knee comprise approximately 8 percent of the nearly 5,000 sarcomas diagnosed each year.      The most common benign tumors are ganglion cysts and plantar fibromas. Synovial sarcomas represent the most common malignant tumor isolated and have a predilection for the lower extremities.2 One must also consider soft tissue tumors of metastatic origin when evaluating the patient with a soft tissue mass. Although rare, there are cases of metatastatic soft tissue neoplasms without osseous involvement.3      There are a number of factors that may influence the development of a soft tissue neoplasm. Hereditary or genetic factors, exposure to chemicals or ionizing radiation, infection, trauma, chronic lymphedema, metastasis and local recurrence of a previous neoplasm have all been implicated in the development of soft tissue tumors.

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