Fibrous dysplasia (FD) is a benign bone neoplasm typified by abnormal fibrous-osseous tissue formed through the fibro-osseous metaplasia, replacing the normal bone marrow. Mostly, the lesion affects a single bone (monostotic form) (Figs. 26.1, 26.2, 26.3, 26.4, 26.5, 26.6, 26.7, 26.8, 26.9, 26.10 and 26.11), and rarely multiple bones of a single extremity and/or homolateral scapula or pelvis (monomelic polyostotic form) (Fig. 26.2e, 26.4a, 26.9e, 26.11e), or may be distributed in several or many bones throughout the body (polymelic polyostotic form) (Figs. 26.12 and 26.13) [1, 2]. A small subset less than 3% of the cases with polyostotic form are associated with McCune-Albright syndrome [3, 4]. Approximately 1–2% of patients with FD, typically of the polyostotic form, are associated with soft tissue myxomas, so-called Mazabraud’s syndrome [3, 5].