[Primary hyperparathyroidism revealed by pseudomyopathia].

We report the case of an 11-year-old child with delayed development who developed signs of exercise-induced pain in the lower limb muscles after an acute attack of appendicitis. He had difficulty standing up from the sitting position and ascending and descending stairs. The physical examination revealed increased reflex activity in the lower limbs. Initially, blood tests, MRI and EMG were normal. Serum phosphorus and calcium were not assayed. Eight months later, the boy's condition worsened (myopathy gait, hyperlordosis) leading to the possible diagnosis of muscle disease. After muscle biopsy, blood tests revealed hypercalcemia at 3.5 mmol/l (normal 2.2-2.6), hypercalciuria, and hypophosporemia. The diagnosis of primary hyperparathyroidism was confirmed by the abnormal level of parathormone initially (19 ng/ml) and later (156 ng/ml) with hypercalcemia. Medical treatment failed and surgery was performed to remove three and a half parathyroid glands. After removal, blood tests returned to normal in six days and the physical examination in three years. The diagnosis of principal cell hyperplasia was retained at the pathology examination. We found no evidence of hypercalcemia or other endocrinopathy such as multiple endocrine neoplasia (MEN 1 or 2a). Study of the menine gene did not reveal any mutation. Muscle dysfunction suggest possible abnormal phosphocalcium regulation. A normal parathormone level with hypercalcemia reveals inappropriate synthesis and secretion.