Ectopic parathyroid hormone syndrome. Occurrence in a case undifferentiated lymphoma with bone marrow involvement

A patient with hypercalcemia, hypophosphatemia, and an undifferentiated lymphoma involving only the bone marrow was treated by us. The finding of an elevated serum parathyroid hormone (PTH) level in the presence of normal parathyroid glands and increased metabolic bone activity on bone biopsy suggests an ectopic PTH syndrome. To our knowledge, no previous case of ectopic PTH syndrome associated with a lymphoma with bone marrow involvement only has been reported.