[Brown tumor of the jaws].

Brown tumour is one of the forms in which fibrous-cystic osteitis, which represents the terminal stage of the bone remodelling processes during primary or secondary hyperparathyroidism, is manifested. For years brown tumour was regarded as a typical lesion of primary hyperparathyroidism, but cases of brown tumours in patients with hyperparathyroidism secondary to renal failure were increasingly often reported in the literature. From an epidemiological point of view, the frequency of brown tumours in patients with renal insufficiency is extremely variable, as is the bone site affected. Several bone segments can be affected at once, but the ethmoid and frontal sinus are rarely reported. Symptoms are caused by the considerable dimensions of the brown tumour and its localisation: in the jawbones it may present sometimes painful, hard and clearly palpable swellings; if large, the tumour may deform the appearance of the bone segments affected or alter the function of the masticatory apparatus. In other cases, there is a complete absence of clinical symptoms and diagnosis may be totally coincidental during the radiological examinations. In histological terms, brown tumours are made up by a cell population consisting of rounded or spindle-like mononucleate elements, mixed with a certain number of plurinucleate giant cells, resembling osteoclastic cells, among which recent haemorrhagic infiltrates and hemosiderin deposits (hence the brown colour) are often found. The aim of this study was to report three cases from a population of 107 patients undergoing haemodialysis at the Turin University Centre. In conclusion, the localisation of maxillary brown tumours appears to prefer a young, female population; brown tumours are rarely an early sign of hyperparathyroidism in haemodialysis patients, but they often appear in conditions of advanced hyperparathyroidism which have escaped medical control either owing to unsuitable therapy or scant patient compliance; they are rapidly evolving lesions whose regression may be very slow or not occur even after total parathyroidectomy; the severity of the lesion caused by a brown tumour may lead to evident osteolysis in the maxillofacial district, thus suggesting the need for early and regular radiological screening; in the event of lesions which are already present, from the authors' point of view, the choice of treatment must be oriented towards parathyroidectomy.