Epithelial neoplasms predominate in the gastrointestinal (GI) tract, as they do in all parenchymal organs and organ systems. However, a wide array of mesenchymal neoplasms also arises in the GI tract, some of which are exclusive or nearly exclusive to…
Cutaneous mesenchymal tumors are considered separately in this chapter because many of the tumors are either unique to or predominate in the skin or show specific features when presenting in the skin. The morphologic spectrum of cutaneous soft tissue tumors…
The vascular system is composed of arteries and veins and their derivatives, capillaries, and lymphatic channels. Although large arteries and veins are readily distinguished histologically, their smaller counterparts can be difficult to differentiate morphologically. In general, veins have a thinner…
Multinucleated giant cells are seen in small numbers in a diverse range of soft tissue tumors. Similarly, soft tissue tumors with prominent giant cells compose a heterogeneous group of benign, intermediate, and malignant neoplasms. Recognition of the various types of…
Although a sparse lymphocytic infiltrate is relatively common in mesenchymal neoplasms, few histologic types of soft tissue tumors characteristically contain prominent inflammatory cells. In some such cases, the presence of an inflammatory infiltrate can be a diagnostic clue, whereas in…
Soft tissue tumors with biphasic histology are uncommon. The “biphasic” designation is often applied to tumors with mixed spindle cell and overtly epithelial (often glandular) components but can also be applied to tumors with mixed spindle cell and epithelioid morphology…
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…
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…