Mimickry in osteogenic sarcoma. Clinical considerations and report of 2 cases.

The authors report two cases of osteogenic sarcoma which presented under the false diagnosis of aneurysmal bone cyst and benign fibrous histiocytoma respectively. This mimickry is discussed: a) It is certainly more common than would appear from the literature, particularly in the case of aneurysmal bone cyst; b) this mimickry applies particularly to the lytic type of osteosarcoma; c) the adjective telangiectatic which is often used to describe malignant bone aneurysms is equivocal; d) immature forms of osteogenic sarcoma all possess a common factor with regard to onset, course and outcome of the disease; e) microscopic anaplastic elements may not always be observed in these imitations; f) clinical examination may often achieve or at least get closer to a true diagnosis of the disease: it is necessary to be aware of the existence of mimetic forms of osteogenic sarcoma and carefully evaluate all the available information; g) surgery should be delayed where clinical doubt exists and the histological report is negative. Such a delay may allow the tumour to reveal its true nature so that the surgeon and oncologist can select the correct treatment.