Water-clear cell parathyroid adenoma causing primary hyperparathyroidism in a patient with neurofibromatosis type 1: report of a case.

Water-clear cell parathyroid adenoma is an exceedingly rare tumor, composed exclusively of tumor cells with abundant foamy cytoplasm. A combination of hyperparathyroidism and neurofibromatosis type 1 (NF1) is also a rare phenomenon. We report an 18-year-old woman with primary hyperparathyroidism caused by water-clear cell parathyroid adenoma in association with NF1. She had renal stones, hypercalcemia, and an elevated plasma level of intact parathyroid hormone. Physical examination revealed a palpable tumor in the right neck, and café-au-lait spots distributed over her entire body. An ultrasound examination showed an isoechoic mass in the right thyroid lobe. Thallium-technetium subtraction scintigraphy showed high thallium accumulation in the right thyroid lobe area. A surgical exploration revealed the palpable mass to be a parathyroid tumor. The pathological features were consistent with water-clear parathyroid adenoma. This is the first reported case of water-clear cell parathyroid adenoma associated with NF1.