[Hypophosphoremic osteomalacia of connective tissue tumors]

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.