Mandibular tumor-induced muscular weakness and osteomalacia.

The case presented is that of a 26-year-old man who suffered from muscular weakness and aching pains 2 years prior to hospitalization. During that period, a tumor in the mandible was diagnosed. During the neurologic work-up to find the cause of the muscular weakness, the possibility of a metabolic bone disease was raised on the basis of oral findings. The giant-cell nature of the mandibular tumor, with destruction of the periodontium, suggested hyperparathyroidism. The giant-cell nature of the mandibular tumor, with destruction of the periodontium, suggested hyperparathyroidism. However, biochemical findings ruled out this diagnosis and led to the final diagnosis of "tumor-induced osteomalacia." Removal of the mandibular tumor caused substantial improvement in the patient's physical condition and in the biochemical picture, which confirmed the diagnosis.