This chapter discusses cartilage and bone-forming lesions in soft tissue. Many of these lesions have a more common intraosseous counterpart. Clinicopathologic features and genetic changes vary between these homologous intraosseous and extraskeletal tumors.

From a historical viewpoint, most of these lesions have been well defined for at least the last one to five decades. Regarding cartilage tumors, Lichtenstein was the first to describe chondroma of soft parts in the hands and feet in 1964; this tumor had been previously described by Jaffe in 1958 in periarticular and intracapsular locations. Synovial chondromatosis was first described by Ambroise Paré in Monsters and Prodigies in 1558 and Laennec in 1813; in 1900, it was identified in the German literature by Reichel. Although Stout and Verner described extraskeletal chondrosarcomas in 1953, the most common variant, extraskeletal myxoid chondrosarcoma, was defined by Enzinger and Shiraki in 1972. Mesenchymal chondrosarcoma was first identified by Lichtenstein and Bernstein in 1959. Bone- or matrix-producing lesions also have been known for a long time. Although it has been known for more than a half-century that tumors can cause oncogenic osteomalacia, the histologic appearance of phosphaturic mesenchymal tumor of the mixed connective tissue type was first reported by Weidner and Santa Cruz in 1987. Tumoral calcinosis has been recognized since 1899 by Duret; it was first described as “tumoral calcinosis” in 1943 by Inclan. Calcium pyrophosphate deposition disease was originally recognized in 1958, but it was McCarty who linked pseudogout caused by crystals of this deposition disease in 1962.