[1][2] It is thought to arise from an outgrowth of immature cartilage cells (chondroblasts) from secondary ossification centers, originating from the epiphyseal plate or some remnant of it.
[6] In a publication by Turcotte et al. it was found that the average duration of symptoms for patients with chondroblastoma was about 20 months, ranging from 5 weeks to 16 years.
[1][5] Romeo et al has noted that chondroblastoma arising in long bones mainly affects the epiphyses, while in other locations it is close to ossification centers.
Additionally, rare prevalence of chondroblastoma in intra-membranous ossification suggests a close relationship with growth plate cartilage.
[2] Both Indian Hedgehog/parathyroid hormone-related protein (IHh/PtHrP) and fibroblast growth factor (FGF) signaling pathways, important for development of the epiphyseal growth plate, are active in chondroblastoma leading to greater proliferation among the cells in the proliferating/pre-hypertrophic zone (cellular-rich area) versus the hypertrophic/calcifying zone (matrix-rich area).
These findings suggest that chondroblastoma is derived from a mesenchymal cell undergoing chondrogenesis via active growth-plate signaling pathways (see Endochondral ossification).
[2][5] However, Edel et al found that collagen II, a marker for mature chondrocytes, was expressed in chondroblastoma, supporting the chondroid nature of the neoplasm.
The results of Romeo and colleagues favor the view of Edel et al of chondroblastoma being cartilaginous in nature but recognize that any definitive determinations regarding the origin of this neoplasm are not possible because of the plasticity of mesenchymal cells when set into different microenvironments and static approaches used in literature.
Romeo et al have observed chondroblastoma neoplasms to be composed of mesenchymal cells that have completed normal chondrogenesis along with the production of osteoid and collagen I that could be the result of transdifferentiation of chondrocytes towards osteoblasts.
For long bone chondroblastomas the tumor is typically contained to the epiphysis or apophysis but may extend through the epiphyseal plate.
Additionally, one-third of all cases involve aneurysmal bone cysts which are thought to be the result of stress, trauma or hemorrhage.
[1] In cases involving older patients or flat bones, typical radiographic presentation is not as common and may mimic aggressive processes.
[1][3][5] The work of Ramappa et al suggests that packing with PMMA may be a more optimal choice because the heat of polymerization of the cement is thought to kill any remaining lesion.
Recurrences are more common in cases involving an open epiphyseal plate where they can be attributed to inadequate curettage to avoid damage.
[1] Recurrences have been shown to occur between 5 months and 7 years after initial treatment and are generally treated with repeat curettage and excision of affected soft-tissue.
[1] The most common location for metastases is the lung, with some cases also involving secondary bone sites, soft tissue, skin, or the liver.
[1] While recurrence is the most common complication of chondroblastoma other issues include post-surgery infection, degenerative joint disease, pathological fractures, failure of bone grafts, pre-mature epiphyseal closure, functional impairment, and malignant transformation.
[1][3] This view was changed later by a comprehensive review completed by Jaffe and Lichtenstein in 1942 of similar tumors in other locations than the proximal humerus.