11 - Mesenchymal Tumors of the Central Nervous System

Abstract

Abstract Mesenchymal tumors involving the central nervous system (CNS) comprise a number of benign, malignant, and non-neoplastic entities. Mesenchymal tumors include entities originating from mesodermal-derived precursor cells that develop into bone, cartilage, or other connective tissues, such as blood vessels, adipose tissue, smooth muscle, or fibroblasts; in the CNS they most commonly arise from the meninges rather than the CNS parenchyma. Histologic features and terminology of these tumors are often identical to the extracranial soft tissue and bone counterparts, yet occasional entities may show unique clinicopathologic or molecular characteristics in the CNS, and the list of tumor types seen in the CNS is typically not as diverse as that in extracranial tissues. This chapter focuses on the tumor types that may be encountered by a surgical pathologist, neurosurgeon, or neuro-oncologist at a relatively higher frequency. The chapter is arranged in general categories of mesenchymal tumors according to cellular differentiation/tissue type, including adipocytic, bone, cartilaginous, notochordal, fibroblastic/myofibroblastic, smooth muscle, skeletal muscle, vascular, primitive tumors, undifferentiated tumors, and miscellaneous. Each subcategory includes a discussion of benign through malignant spectrum of lesions, with sections on definitions, clinical manifestations, radiologic features and gross pathology, histopathology, variants and/or grading, differential diagnosis, ancillary studies, genetics, and finally treatments/prognosis. In the revised edition, we have placed a greater emphasis on molecular diagnostics in CNS mesenchymal tumors.