Osteoid osteoma is an osteocalcinoma affecting glucose metabolism.

Osteocalcin is a hormone secreted by osteoblasts, which regulates energy metabolism by increasing ß-cell proliferation, insulin secretion, insulin sensitivity, and energy expenditure. This has been demonstrated in mice, but to date, the evidence implicating osteocalcin in the regulation of energy metabolism in humans are indirect. To address this question more directly, we asked whether a benign osteoblastic tumor, such as osteoma osteoid in young adults, may secrete osteocalcin. The study was designed to assess the effect of surgical resection of osteoid osteoma on osteocalcin and blood glucose levels in comparison with patients undergoing knee surgery and healthy volunteers. Blood collections were performed the day of surgery and the following morning after overnight fasting. Patients and controls were recruited in the orthopedic surgery department of New York Presbiterian Hospital, NY-USA and Hospices Civils de Lyon, France. Seven young males were included in the study: two had osteoid osteoma, two underwent knee surgery, and three were healthy volunteers. After resection of the osteoid osteomas, we observed a decrease of osteocalcin by 62% and 30% from the initial levels. Simultaneously, blood glucose increased respectively by 32% and 15%. Bone turnover markers were not affected. This case study shows for the first time that osteocalcin in humans affects blood glucose level. This study also suggests that ostoid osteoma may be considered, at least in part, as an osteocalcinoma.

[Hypophosphoremic osteomalacia of connective tissue tumors]. / L'ostéomalacie hypophosphorémique des tumeurs du tissu conjonctif.

The authors undertake a general review of the association between hypophosphoraemia and connective tissue tumour, based upon three personal cases and 27 cases of benign connective tissue tumours, as well as cases of hypophosphoraemia related to malignant tumours or to diffuse dysplasia of connective tissue origin, collected from the literature. This syndrome is distinguished from hypophosphoraemia induced by other tumours (myeloma, carcinoma of the prostate) which are based upon different mechanisms. Hypophosphoraemia, associated with a fall in plasma levels of 1-25 (OH)2 D3 by inhibition of renal 1 alpha hydroxylase, suggests the existence of a complex tubular deficit. Removal of the tumour, most often vascular and intra- or para-osseous, results in rapid normalisation of laboratory then radiological and clinical abnormalities. The physiopathology of the syndrome remains very mysterious. It may be likened to certain tubulotoxic syndromes due to cadmium and in particular to maleic acid. However no precise data yet exists regarding any possible abnormal tumour secretion. In practice, any case of hypophosphoraemic osteomalacia requires investigation to locate a possible tumour of connective tissue, and this all the more so when it is accompanied by very low plasma levels of 1-25(OH)2 D2.