Chondrosarcoma is a malignant bone tumor arising from cartilaginous tissue, most frequently occuring at the ends of the femur and tibia, the proximal end of the humerus and the pelvis; and presenting with a palpable mass and progressive pain. Chondrosarcoma is usually slow growing at low histological grades and can be well managed by intralesional curettage or en-block wide resection.

The tree-in-bud pattern represents centrilobular branching structures that resemble a budding tree. The pattern reflects a spectrum of endo- and peribronchiolar disorders, including mucoid impaction, inflammation, and/or fibrosis (See Figure 70 of PMID:18195376).