Molecular Pathology of Bone Tumors.

Although classic histomorphology is the cornerstone of bone tumor diagnostics, this field has rapidly evolved since the advancement of new molecular techniques. The identification of novel genetic alterations in bone tumors has led to more insight into the genetic background of these tumors, which has resulted in a more prominent role of molecular pathology in daily practice. Numerous studies have been conducted in the past few decades and illustrated that based on molecular alterations, bone tumors can be roughly classified as tumors with simple karyotypes and those with complex karyotypes. The first group can be subclassified as tumors that carry specific translocations, somatic gene mutations, or more or less specific amplifications. On the other hand, sarcomas with complex karyotypes usually lack specific alterations. Many techniques are available for the detection of recurrent genetic alterations, now also including IHC analysis, and this review focuses on assays routinely performed in molecular diagnostics. Subsequently, tumor classes with distinct genetic abnormalities are discussed and illustrated by more specific examples, and the usefulness of molecular pathology in routine diagnostics is highlighted.