Fibrous Tumors

Abstract

The lesions in this category include both neoplastic and nonneoplastic lesions that contain fibrous constituents (i.e., collagen). The World Health Organization (WHO) groups fibrous bone lesions into two main categories: (1) fibrogenic and (2) fibrohistiocytic tumors. However, unlike the WHO classification, this chapter also includes fibrous dysplasia (FD) and fibrous xanthomas [fibrous cortical defects (FCD) and nonossifying fibromas (NOFs)]. The WHO actually classifies FD as a miscellaneous lesion with “undefined neoplastic nature” and excludes fibrous xanthomas, even though they have fibrohistiocytic constituents, probably because they are considered developmental defects that often heal, rather than true bone tumors. Nonetheless, these lesions are commonly encountered and we include them here for completeness. In fact, aside from fibrous xanthomas and FD, most of these lesions are quite rare. In general, fibrous lesions appear as lucent areas on radiographs due to the absence of mature bony matrix.