Endocrine Abstracts

Background: Osteolytic metastases of the bone occur in several malignant tumors. Beside osseous metastases, endocrine diseases like primary hyperparathyroidism can mimic osteolytic metastases.

Case report: A 53-year-old woman was sent to the hospital by an oral surgeon with a worsening of her general condition, fatigue, a painful tumor of the mandible, diffuse bone pain and the diagnosis of a suspected metastasized malignancy. Laboratory testing showed a severe hypocalcaemia and a massive elevation of parathyroid hormone levels. A bone scintigraphy showed an enhancement in the mandible as well as several other lesions in the costae, the sacrum and the right ankle. Histological examination of a tumor biopsy indicated a giant cell tumor. CT scans of the abdomen and thorax showed calcification of the stomach and diffuse calcifications of the kidneys, but no tumor. A cervical sonography showed a nodal lesion at the lower part of the right thyreoidal lobe consistent with an enlarged polar body. In synopsis of all diagnostic findings, the diagnosis of a primary hyperparathyroidism with so called ‘brown tumor’ of the mandible and osteitis fibrosa cystica was made. The parathyroid gland was surgically resected and histological examination showed an adenoma of the parathyroid gland. Three months after surgery, a complete remission of the hyperparathyroidism as well as a regression of the tumor of the mandible and the skeletal lesions were documented.

Discussion: It has been demonstrated here that multiple osteolytic lesions and hypocalcaemia do occur not only in metastatic malignant tumors but are also found in endocrine diseases like primary hyperparathyroidism. Therefore, a careful diagnostic workup is essential in ensuring an optimal treatment. As in the present case, diagnosis is sometimes complicated due to the clinical appearance and histological differentiation between a giant cell tumor and the so called ‘brown tumor’ associated with primary hyperparathyroidism.