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Objective: This study was undertaken to describe the musculoskeletal manifestations in a selected population of 26 patients with biopsy-proven osteomalacia (OM) and provide a literature update., Methods: The 26 patients with biopsy-proven OM were selected from a total number of 79 patients who underwent anterior iliac crest biopsy. The diagnosis of OM was confirmed by the presence of an osteoid volume greater than 10%, osteoid width greater than 15 microm, and delayed mineralization assessed by double-tetracycline labeling., Results: OM was caused by intestinal malabsorption in 13 patients, whereas six other patients presented with hypophosphatemia of different causes. Five elderly patients presented with hypovitaminosis D, and in two patients the OM was part of renal osteodystrophy. Twenty-three patients presented with bone pain and diffuse demineralization, whereas three other patients had normal or increased bone density. Characteristic pseudofractures were seen in only seven patients. Six of the 23 patients with diffuse demineralization had an "osteoporotic-like pattern" without pseudofractures. Prominent articular manifestations were seen in seven patients, including a rheumatoid arthritis-like picture in three, osteogenic synovitis in three, and ankylosing spondylitis-like in one. Two other patients were referred to us with the diagnosis of possible metastatic bone disease attributable to polyostotic areas of increased radio nuclide uptake caused by pseudofractures. Six patients also had proximal myopathy, two elderly patients were diagnosed as having polymalgia rheumatica, and two young patients were diagnosed as having fibromyalgia. One of the patients who presented with increased bone density was misdiagnosed as possible fluorosis., Conclusion: OM is usually neglected when compared with other metabolic bone diseases and may present with a variety of clinical and radiographic manifestations mimicking other musculoskeletal disorders.

The Fanconi syndrome is a generalized disorder of proximal renal tubular transport characterized by wasting of phosphate, amino acids, glucose, bicarbonate, and uric acid. The association of the acquired Fanconi syndrome with lambda light-chain proteinuria is rare. We report the third case in the English language literature. A 65-year-old man presented with severe pelvic pain. Investigations showed an elevated serum creatinine level, and a 24-hour urine collection contained 2.56 g protein. The Fanconi syndrome was diagnosed, with findings of phosphaturia, glycosuria, and aminoaciduria. Bence Jones protein (lambda sub-type) was present in the urine at a concentration of 0.58 g/L. Monocytic cells in the bone marrow and proximal tubular cells in the kidney contained cytoplasmic crystalline inclusions. Undecalcified bone sections confirmed the clinical diagnosis of osteomalacia. The patient was treated with phosphate, calcium, and ergocalciferol and experienced significant symptomatic improvement. The Fanconi syndrome caused by light-chain deposition in proximal tubular cells is well described in the literature. However, it is rare for the light chains to be of the lambda subtype. This may reflect differences in the physicochemical properties of kappa and lambda light chains.

Rickets, osteomalacia, and renal osteodystrophy are disorders of the mineralization of bone that result from a lack of available calcium, phosphorus, or both. The diseases that result from numerous mechanisms present with a symptom-sign-radiographic complex with such a high degree of stereotypy that laboratory investigation is often required to distinguish one form from another. The disorders in children, known as rickets, produce bowing and other deformities of the long bones and dwarfism. These disorders are principally related to the profound effect of the deficiency states on the epiphyseal plate; whereas the same disorders in adults produce an often severe osteopenia and pathologic fractures. Because of newer developments in our understanding of the factors affecting calcium-phosphorus hemostasis and vitamin D metabolism, many of the children and adults with these disorders can now be treated effectively.