The association of neurofibromatosis 1 and spinal deformity with primary hyperparathyroidism and osteomalacia: might melatonin have a role?

A 35-year-old woman with neurofibromatosis 1 and thoracic kyphoscoliosis had incomplete paraplegia. She had a history of hyperparathyroidism due to a parathyroid adenoma which had been excised 4 years previously. Plain radiographs of the spine revealed kyphoscoliosis from the third to sixth thoracic vertebrae. Kyphosis and scoliosis angles were 86 degrees and 28 degrees, respectively. Radiographs of the skull and hands showed radiological changes suggestive of hyperparathyroidism. Laboratory tests showed low-normal serum calcium, hypophosphatemia, elevated serum alkaline phosphatase, and low serum 25-hydroxyvitamin D. Retrospective review of the patient's laboratory data showed that she had osteomalacia at the time of diagnosis of primary hyperparathyroidism. The patient had been treated by anterior and posterior decompression and fusion with posterior instrumentation through a single posterior approach. The postoperative kyphosis and scoliosis angles were 30 degrees and 12 degrees, respectively. Neurological recovery and spinal fusion had been achieved. Osteomalacia responded well to vitamin D therapy. This is the first case of coexisting neurofibromatosis 1, primary hyperparathyroidism due to parathyroid adenoma and osteomalacia to be reported in the literature. The osteomalacia in this patient could be related to primary hyperparathyroidism, and not to neurofibromatosis 1. A drop in melatonin level after parathyroidectomy may have been the cause of spinal curvature progression in this patient.