Endocrine Abstracts

Objective: Tumor induced osteomalacia (TIO) belongs to the group of hypophosphatemic osteomalacias and is induced by a tumor. It is not common disease.

Case report: We describe a 34-year-old caucasian man who presented with a 5 year history of diffuse bone pain and muscle weakness. Laboratory investigations showed normal calcium level, low phosphate level between 1.01 mg/dl, and 1.6 mg/dl (reference range: 2.6–5.5 mg/dl), raised alkaline phosphatase of 238 and 885 IU/l (reference range: 30–120 IU/l) and high urinary phosphate level. Intact parathyroid hormone was within normal range (50.61 pg/ml; normal reference range 15–65 pg/ml). The plasma concentration of 1–25(OH) 2D was at the lower limit of the normal range (20 pg/ml; reference range 20–30 pg/ml). The tubular reabsorbtion of phosphate (TRP) was 65% (normal range 85–95%). Chest radiograph showed decreased bone mineralization and multiple fractured ribs. Conventional radiographs also showed fractures at the femoral necks bilaterally. There was no etiology of hypophosphatemia. The clinical, biological and radiological findings were compatible with osteomalacia, possibly related to the tumor. The patient was then further evaluated by magnetic resonance imaging (MRI), which showed marked intensity changes at the vertebrae corpuses due to osteoporosis, decreased signal intensities at the femoral necks due to fractures bilaterally, multiple transverse fractures at the proximal and distal metaphysis of tibias bilaterally. However this MRI images didn’t show possible finding which associated tumor. But on pelvic MRI, we detected a hypointense lesion at the superior and posterior surface of the acetabulum measuring 13 mm in diameter. An excision of the mass was performed and histological diagnosis of hemangioma was established. Upon removal of the tumor, laboratory data returned to a normal range within one month.