Isolated bone lesion secondary to hyperparathyroidism: diagnostic considerations.

Authors describe two cases of bone lesions ("brown" tumour) secondary to hyperparathyroidism in whom incisional biopsy gave an incorrect diagnosis. The first case was a patient with a lesion of the right femur diagnosed as aneurismal cyst and; the second case was a patient with an isolated lesion of the distal metaphysic of right humerus firstly diagnosed as giant cells tumour. Treatment of the first case was resection and diaphyseal spacer, and the correct diagnosis of brown tumour was performed for the multiple tibial localizations appeared six months later. The second case was diagnosed as affected by a brown tumour secondary to hyperparathyroidism on the basis of clinical history and laboratory analysis. Both diagnoses were firstly incorrect and would have brought to an inadequate treatment with consequences on patients quality life. Differential diagnosis is discussed and the importance to evaluate all the diagnostic data to formulate a correct diagnosis is stressed.