Soft tissue tumors comprise a group of entities showing mesenchymal differentiation which can be located in skin, subeutis, or deep soft tissue. The latter includes subfascial limb and limb girdle tumors, and those located in head and neck, abdomen, retroperitoneum (including paratestis), pelvis, and thoracic and intracranial cavities. Similar lesions can also involve viscera. Typically, soft tissue tumors are classified by the tpe of differentiation which they display, and the principal objectives of the surgical pathologist are to identify the lineage of the lesional cells and asses their malignant potential. Nonmesenchymal lesions such as carcinoma or melanoma can also present as soft tissue neoplasms.
In many cases, the tumor is seen initially as a spindle cell, epithelioid cell, small round cell, or pleomorphic lesion which needs to be characterized further with the aid of ancillary techniques including immunohistochemistry, electron microscopy, and genetic analysis. Lesions with adipose, osteochondroid, or vascular space formation can readily be identified morphologically but often present difficulties in precise subcategorization and in assessment of malignancy.
In many cases, the tumor is seen initially as a spindle cell, epithelioid cell, small round cell, or pleomorphic lesion which needs to be characterized further with the aid of ancillary techniques including immunohistochemistry, electron microscopy, and genetic analysis. Lesions with adipose, osteochondroid, or vascular space formation can readily be identified morphologically but often present difficulties in precise subcategorization and in assessment of malignancy.