How are soft-tissue tumors classified?

Updated: Dec 03, 2018
  • Author: Vinod B Shidham, MD, FRCPath; Chief Editor: Omohodion (Odion) Binitie, MD  more...
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Answer

The outline below comprises the histologic classification of soft-tissue tumors. The histopathologic evaluation of these lesions, with categorization into one of the groups listed below, is performed on permanent sections. Such classification may require data from various sources, including immunochemical, cytogenetic, electron microscopic, and molecular studies.

Sarcomas usually are assigned a histologic grade. Low-grade lesions rarely metastasize but can be locally aggressive; high-grade sarcomas pose a significant threat of metastasis and carry a greater risk of local recurrence. Although assigning a pathologic grade to an individual tumor is a subjective and difficult task, the grade's clinical importance in determining a treatment strategy cannot be overemphasized. An ideal biopsy, with proper sampling of the lesion, should allow a confident grade assignment.

Many grading systems exist; they generally are based on evaluation of histomorphologic features, including cellularity, cellular pleomorphism, mitotic activity, and necrosis, as well as histologic category. [30, 31, 32] A three-grade system (grades 1, 2, 3) may be simplified further by lumping the sarcomas into low-grade (grade 1) and high-grade (grade 2) categories.

Other markers have been investigated as potential indicators of proliferation activity of soft tissue tumors. They include Ki-67, argyrophilic stain for nucleolar organizer regions (AgNOR), mast cell counts, and DNA flow cytometry.


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