Plasmacytoma mimicking mediastinal parathyroid tumour in a patient with primary hyperparathyroidism

The association of monoclonal gammopathies with primary hyperparathyroidism is well documented. Many case reports have documented the coexistence of primary hyperparathyroidism and multiple myeloma. The cause of this relationship is not known. We report the case of a 49-year-old gentleman who was treated for primary hyperparathyroidism. His initial preoperative nuclear scan had shown persistent activity and retention of tracer in the retrosternal region in addition to the discrete hot spot in the region of the lower pole of the left lobe of the thyroid. During surgery, the enlarged left inferior parathyroid gland was removed. In addition, the retrosternal area was also explored and found to be normal. Ten months later, he developed a mass in the region of the manubrium sternii which was proven to be a plasmacytoma. Were view the literature for similar cases and suggest hypotheses for a possible association. In conclusion, coexisting plasma cell dyscrasias including plasmacytoma should be considered in patients with primary hyperparathyroidism.