Tumour-Like Lesions of Bone

Abstract

Tumour-like lesions of the bone consist of a very heterogenous group of lesions with different aetiology and clinico-radiological appearence. They can cause diagnostic as well as therapeutic problems. Both neglect and overtreatment of the lesions should be avoided. Unicameral and aneurysmal bone cysts, intra-osseal ganglia, non-ossifying fibroma, fibrous dysplasia, myositis ossificans, bone infarct and giant-cell reparative granuloma of bone are disscussed in this chapter as the most frequent and significant representatives of this group.

The surgical staging system according Enneking et al. can be well adapted to the tumour-like lesions and this classification enables us to plan the surgical intervention.

Stage 1 lesions such as non-ossifying fibromas, bone infarcts and small circumscribed fibrous dysplasias are usually found accidentally on the radiographs and they require observation in most cases. Surgery is considered rarely in cases of pathological fracture or when the quality of life is influenced significantly by decreasing of the range of movement or entrapped nerves cause complaints in cases of post-traumatic myositis ossificans.

In stage 2 lesions such as intra-osseal ganglia or giant-cell reparative granuloma, curettage and grafting with homologous bone is the standard treatment. However, in cases of unicameral (UBC) and aneurysmal bone cyst (ABC) a broad spectrum of treatment options is described in the literature.

Evidence has accummulated that conservative surgical treatment of the unicameral bone cyst, i.e. by methylprednisolone acetate injections, the use of percutaneous cannulated screws or flexible intramedullary nails which decrease the intracystic pressure and percutaneous grafting of demineralized bone matrix and autologous bone marrow have comparable results with those of open surgery, curettage and grafting. The reported rate of recurrences is similar in both groups and varies from 12 % to 30 % depending on the type of the UBC. Active UBCs are more difficult to treat and recur in a higher percentage. The advantage of the percutaneous techniques is, however, the less operation-related morbidity and faster recovery for the patients.

The more aggressive growth of the stage 3 ABC necessiates more aggressive treatment as well. Percutaneous procedures similar to that used in UBC are either ineffective (decompression by Kirschner wires, methylprednisolone acetate injection) or can have significant side effects and complications (calcitonin hormone injection, sclerotisation by alcoholic solution, radiation) and should only be used for certain indications (pelvic location, etc.). Hypervascular ABCs should be embolized prior to surgery to avoid excessive intra-operative bleeding. Some of them heal and show good ossification if embolization is used alone. All these procedures mentioned above have a similar and not less local recurrence rate than open surgery, curettage and grafting with adjuvant therapy (cryosurgery, phenol, bone cement impaction). This latter form of treatment has, however, the advantage that it is possible to obtain sufficient material for histological evaluation. Because one third of the ABC are secondary, developing in association with other tumours, this may cause differential diagnostic problems (teleangiectatic osteosarcoma). This is a strong argument for choosing open surgery as first line of the treatment.

Post-traumatic myositis ossificans needs only to be operated on when the diagnosis is unsure or the calcified mass causes permanent clinical symptoms. The resection should be delayed until maturation is complete, around 4–6 months after onset of the process.

In the extensive or polyostotic form of fibrous dysplasia (FD) often the deformities or pathological fractures nessecitate a surgical intervention. The choice of devices depends on the location of the FD but intramedullary fixation shows superior results to plating and screwing in the weakened bone. Bisphosphonates have been shown to offer pain relief and improve skeletal strength in FD, but medical treatment with bisphosphonates in patients with FD is still controversal.