Secondary amyloidosis in relation to carcinoma of the kidney.

The clinical and biochemical findings are, however, not those generally associated with osteomalacia. The plasma calcium, phosphorus and alkaline phosphatase were all normal. Urinary calcium estimations were normal and calcium and phosphorus balance was strongly positive. Furthermore, no Looser's zones were identifiable in the skeleton and the disorder had a prolonged clinical course with failure of response to vitamin D at doses varying from 1500 to 20,000 units/day. Axial osteomalacia is difficult to distinguish from fibrogenesis imperfecta ossium on radiological grounds alone. Radiologically axial osteomalacia is characterized by a coarsening and distension of the trabecular pattern of the cervical vertebrae, lumbar vertebrae, ribs, and pelvis. (Figs. 1-4.) The more peripheral parts of the skeleton appear radiologically normal, unlike fibrogenesis imperfecta where they may not infrequently be involved. Histological examination of bone tissue from patients with fibrogenesis imperfecta ossium show a deficiency of collagen fibres as detected by the absence of birefringence with the polarizing microscope. There was, however, no histological evidence to suggest a diagnosis of fibrogenesis imperfecta ossium in the patient we have described. Urinary mucopolysaccharide and urinary hydroxyproline estimations were normal. The prognosis of patients with 'axial osteomalacia' appears to be reasonably good. One patient followed up for 5 years is still well without treatment (Arnstein et al., 1967) and the symptoms and radiological findings of our patient have not changed for 18 years. Therapy with vitamin D, 20,000 units daily for 3 years has not induced any detectable alteration in bone biopsy histology and this fact together with the normal plasma biochemistry and positive calcium and phosphorus balance data strongly suggest that the disorder is not a true osteomalacia.