What is Clonal Tracking

The bone and bone marrow are common sites for metastasis due to their high vascularity and niche components. The commonest primaries in adults are the lung, prostate, and breast. Neuroblastoma, osteosarcoma, and Ewing sarcoma are the most frequent in children. The mechanism of tumor spread involves a multistep process with underlying molecular changes involving the interaction between tumor cells and the marrow microenvironment. Sometimes metastatic spread to the bone marrow manifests in peripheral blood changes, including cytopenia and leucoerythroblastic changes, in which case the bone marrow may be the first tissue diagnosis of the tumor. The bone marrow morphology and IHC help identify the primary tumor, though it remains unknown in some cases. The presence of metastasis often implies a poor prognosis.