Osteitis fibrosa cystica simulating metastatic tumor. An almost-forgotten relationship.

The diagnosis of primary hyperparathyroidism most often results from the incidental finding of hypercalcemia. In two recent cases of osteitis fibrosa cystica (OFC), however, patients without adequate access to health care served as graphic reminders that the clinical spectrum of the disease includes bone disease, and that OFC can be the presenting manifestation of long-standing primary hyperparathyroidism. Both patients complained of bone pain and had widespread osteolytic bone lesions in addition to hypercalcemia on a multitest biochemical panel. The presumptive diagnosis of malignancy with bone involvement (metastatic cancer or multiple myeloma) led to random bone marrow trephine biopsies. Examination of the bone marrow biopsy material revealed the characteristic pathology of OFC, leading to appropriate diagnosis and surgical management of large parathyroid adenomas in both patients.