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Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
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Chondroblastoma has not been known to spontaneously heal and the standard treatment is surgical curettage of the lesion with bone grafting. To prevent recurrence or complications it is important to excise the entire tumor following strict oncologic criteria. However, in skeletally immature patients intraoperative fluoroscopy may be helpful to avoid destruction of the epiphyseal plate. In patients who are near the end of skeletal growth, complete curettage of the growth plate is an option. In addition to curettage, electric or chemical cauterization (via phenol) can be used as well as cryotherapy and wide or marginal resection. Depending on the size of the subsequent defect, autograft or allograft bone grafts are the preferred filling materials. Other options include substituting polymethylmethacrylate (PMMA) or fat implantation in place of the bone graft. 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.
Both radiotherapy and chemotherapy are not commonly used. Radiotherapy has been implemented in chondroblastoma cases that are at increased risk of being more aggressive and are suspected of malignant transformation. Furthermore, radiofrequency ablation has been used, but is typically most successful for small chondroblastoma lesions (approximately 1.5 cm). Treatment with radiofrequency ablation is highly dependent on size and location due to the increased risk of larger, weight-bearing lesions being at an increased risk for articular collapse and recurrence.
Overall, the success and method of treatment is highly dependent upon the location and size of the chondroblastoma.
General treatment regimens have not changed much in the past 30 years, in part due to the lack of randomized clinical trials. Surgery is the treatment of choice if the tumor is determined to be resectable. Curettage is a commonly used technique. The situation is complicated in a patient with a pathological fracture. It may be best to immobilize the affected limb and wait for the fracture to heal before performing surgery.
Patients with tumors that are not amenable to surgery are treated with radiation therapy. However caution is employed since a majority of recurrent tumors with transformations to the malignant sarcoma phenotype have been in patients receiving radiotherapy for their primary benign lesion. Pharmacotherapy for GCTOB, includes bisphosphonates such as Zoledronate, which are thought to induce apoptosis in the MNGC fraction, preventing tumor-induced osteolysis. Indeed, "in vitro" studies have shown zolidronate to be effective in killing osteoclast-like cells. More recently, humanized monoclonal antibodies such as Denosumab targeting the RANK ligand have been employed in treatment of GCTOB in a phase II study. This is based on the notion that increased expression of RANK-ligands by stromal cells plays a role in tumor pathogenesis.
Curettage is performed on some patients, and is sufficient for inactive lesions. The recurrence rate with curettage is significant in active lesions, and marginal resection has been advised. Liquid nitrogen, phenol, methyl methacrylate are considered for use to kill cells at margins of resected cyst.
Although not specific to one mode of management, lesion size, patient sex, or follow-up, the recurrence rate for chondroblastoma is relatively high, and has been shown in select studies to be dependent upon the anatomical location, method of treatment, and biological aggressiveness of the initial lesion. The rate of recurrence is highly variable, ranging between 5% and 40%, as study results are generally inconclusive. However, local recurrence for long bone lesions is around 10%, with chondroblastoma in flat bones having higher recurrence and more complications. Recurrences are more common in cases involving an open epiphyseal plate where they can be attributed to inadequate curettage to avoid damage. Lesions of the proximal femur are particularly problematic because of difficulties accessing the femoral head for complete excision. Chondroblastoma may recur in the soft tissue surrounding the initial lesion, especially in the case of incomplete curettage. 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. No histological differences have been seen between recurrent and non-recurrent chondroblastomas.
Rarely, more aggressive chondroblastomas can metastasize. The most common location for metastases is the lung, with some cases also involving secondary bone sites, soft tissue, skin, or the liver. The prevalence of metastatic chondroblastoma, however, is quite low and is believed to be less than 1%. There is no relationship established between metastasis and previous surgery, non-surgical treatment, anatomical location, or patient age. Survival of patients with metastatic lesions is better when the metastases are surgically resectable, as chemotherapy has been shown to have little to no benefit. Prognosis is bleak for patients with malignant chondroblastomas that are resistant to surgery, radiation, and chemotherapy. However, patients with resectable metastases have survived for several years following diagnosis.
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. Complications are less common in patients presenting with chondroblastoma in accessible areas. Overall, patients with more classical chondroblastoma (appearing in long bones, typical presentation) have better prognoses than patients with atypical chondroblastoma (flat bones, skull, etc.).
A number of tumors have giant cells, but are not true benign giant-cell tumors. These include, aneurysmal bone cyst, chondroblastoma, simple bone cyst, osteoid osteoma, osteoblastoma, osteosarcoma, giant-cell reparative granuloma, and brown tumor of hyperparathyroidism.
Recurrence rate of solid form of tumour is lower than classic form.
A blastoma is a type of cancer, more common in children, that is caused by malignancies in precursor cells, often called blasts. Examples are nephroblastoma, medulloblastoma and retinoblastoma. The suffix "-blastoma" is used to imply a tumor of primitive, incompletely differentiated (or precursor) cells, e.g., chondroblastoma is composed of cells resembling the precursor of chondrocytes.
Many types of blastoma have been linked to a mutation in tumor suppressor genes. For example, pleuropulmonary blastomas have been linked to a mutation of the coding for p53. However, the mutation which allows proliferation of incompletely differentiated cells can vary from patient to patient and a mutation can alter the prognosis. In the case of retinoblastoma, patients carry a visibly abnormal karyotype, with a loss of function mutation on a specific band of chromosome 13. This recessive deletion on the rb gene is also associated with other cancer types and must be present on both alleles, for a normal cell to progress towards malignancy.