What is the pathophysiology of soft-tissue tumors?

Updated: Dec 03, 2018
  • Author: Vinod B Shidham, MD, FRCPath; Chief Editor: Omohodion (Odion) Binitie, MD  more...
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Generally, soft-tissue tumors grow centripetally, though some benign tumors (eg, fibrous lesions) may grow longitudinally along tissue planes. Most soft-tissue tumors respect fascial boundaries, remaining confined to the compartment of origin until the later stages of development.

Once the tumor reaches the anatomic limits of the compartment, the tumor is more likely to breach compartmental boundaries. Major neurovascular structures usually are displaced as opposed to being enveloped or invaded by tumor. Tumors arising in extracompartmental locations, such as the popliteal fossa, may expand more quickly because of a lack of fascial boundaries; they are also more likely to involve neurovascular structures.

The peripheral portion of the tumor compresses surrounding, normal soft tissue because of centripetal expansile growth. This results in the formation of a relatively well-defined zone of compressed fibrous tissue that may contain scattered tumor cells. This zone may also consist of inflammatory cells and demonstrate neovascularity.

A thin layer of tissue called the reactive zone surrounds the compression zone, especially in higher-grade tumors. Together, the compression and reactive zones form a pseudocapsule that encloses the tumor and is useful in defining the extent of surgical resection.

Some extremely aggressive lesions with infiltrative growth patterns, such as childhood rhabdomyosarcoma, may not respect anatomic compartmental boundaries and frequently will invade fascial planes.

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