Soft Tissue Masses: When To Treat, When To Refer

By Bradley W. Bakotic, DPM, DO

The recognition and characterization of soft tissue tumors is central to the practice of podiatric medicine. In many instances, clinicians of the lower extremity serve as the frontline physicians when it comes to the identification of such tumors. Given the inverse relationship between the amount of time prior to diagnosis and patient survival rates, the role of podiatrists may be of paramount importance. Depending upon one’s depth of experience and comfort level, some clinicians might limit their role to clinical recognition and ordering preliminary imaging studies. Others may go a step further and definitively characterize the lesion in question through needle aspiration, Tru-Cut core needle biopsy or incisional biopsy. In some instances, it is the podiatric surgeon who will provide definitive surgical management. The medical community at large is increasingly relying on the podiatric profession to recognize and raise awareness of skin, bone and soft tissue tumors of the lower extremity. Unfortunately, when podiatrists fail to diagnose these conditions, the resultant void may have grave consequences. Understanding And Defining Soft Tissue Tumors And Neoplasms The “soft tissue” is composed of all living tissue with the exception of that which is skeletal, epithelial, hematopoietic (bone marrow derived) and parenchymal (the functioning tissue of visceral organs). The nervous system is divided in such a way that the nerves and glia of the central nervous system are not considered part of the soft tissue but the nerves and nerves sheath of the peripheral nervous system are considered part of the soft tissue. In general terms, the soft tissues consist of adipose tissue, fibrous tissue, muscle, vascular structures and peripheral nerves. Accordingly, a pyogenic granuloma (composed of vessels) is a soft tissue tumor while squamous cell carcinomas and verrucae are not. Precisely what falls under the designation “soft tissue” does become a bit more complicated as some neoplasms of disputed differentiation are also under the classification of “soft tissue.” Some examples of this are synovial sarcoma and epithelioid sarcoma. Tumors of the soft tissue include all mass-forming lesions that are either composed of soft tissue or exhibit differentiation toward any type of soft tissue. It is important to note that although the central nervous system, visceral organs and skeletal system are not considered to be part of the soft tissue, they all have soft tissue within them in the form of vascular structures, adipose tissue, fibrous tissue and/or peripheral nerves. It is probably for this reason that we occasionally see tumors of the fibrous tissue (fibromatosis/pleomorphic fibroma, fibrosarcoma), adipose tissue (lipoma, liposarcoma) and smooth muscle (leiomyoma, leiomyosarcoma) arising in these unusual locations. Each type of soft tissue tumor has its own distinct pattern of distribution. Overall, however, the most common locations for soft tissue neoplasms are the retroperitoneum/pelvis and thigh. For clinicians who specialize in the care of the lower extremity, notable exceptions exist. Examples of soft tissue tumors that have a predilection for the distal extremities are synovial sarcoma, epithelioid sarcoma and clear cell sarcoma (melanoma of soft parts). One additional point that is highly relevant to the topic of soft tissue tumors involves the meaning of the term neoplasm. While soft tissue tumor refers to any mass occupying lesion that is composed of soft tissue elements, soft tissue neoplasm denotes only those tumors that emanate from a single genetically identical mother cell and proliferate as autogenous new growths (e.g., neoplasms). In other words, neoplasms begin with a genetic mutation or a series of genetic mutations within an individual mother cell, which results in immortality and the ability for that cell to replicate beyond normal physiologic limitations. This uncontrolled duplication of the mother cell ultimately leads to the formation of a mass. Neoplasms may be further subdivided into those that are benign and those that are malignant. A ganglion cyst is an example of a non-neoplastic soft tissue tumor, a lipoma is a benign neoplasm, a synovial sarcoma is a malignant neoplasm, etc. Unfortunately, the precise characterization of soft tissue neoplasms as benign or malignant may also be controversial.

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