The term small round blue cell tumors is used to refer to a group of generally highly aggressive malignant neoplasms, seen under the microscope as monotonous proliferations of small cells with scant cytoplasm. This category classically includes certain subtypes of…
Pleomorphic sarcomas are defined as malignant mesenchymal neoplasms characterized at a histologic level by prominent cellular pleomorphism and often brisk mitotic activity, with or without a readily identifiable line of differentiation. Cellular pleomorphism in mesenchymal neoplasms is probably best defined…
The group of epithelioid mesenchymal tumors encompasses neoplasms that are composed, partly or extensively, of rounded or polygonal cells, at least somewhat resembling epithelial cells ( Boxes 6.1 to 6.3 ). These tumors show variable, sometimes misleading growth patterns, including…
Myxoid tumors of soft tissue are remarkable for their characteristic abundant extracellular matrix material. This heterogeneous group of lesions includes benign (and self-limited) tumors, those with a significant potential for local recurrence, and sarcomas. Because there is considerable clinical and…
Spindle cell tumors in children and adolescents encompass a wide range of benign, intermediate, and malignant neoplasms, with the predominant phenotypic category being fibroblastic-myofibroblastic tumors. The most frequent spindle cell sarcomas of childhood include spindle cell and embryonal rhabdomyosarcoma (RMS),…
Numerous primary tumors and pseudotumors of soft tissues contain a variable number of spindle cells. In this chapter the authors will discuss only those lesions composed exclusively or predominantly of spindle cells that develop in adult patients and for which…
Biologic Potential Among the most important reasons for the accurate classification of soft tissue tumors is the communication of clinical behavior (i.e., assignment into a managerial category). The vast majority of soft tissue tumors can be classified as either benign…
Tumor Classification Soft tissue tumors have traditionally been classified according to line of differentiation—that is, which normal cell type the neoplastic cells most closely resemble. Such a “lineage” can often be assigned based on a combination of histologic appearances, patterns…