[A bone-destroying tumor of the maxilla. Reparative giant cell granuloma or brown tumor?]

Brown tumors are focal bone lesions caused by an increased osteoclastic activity and fibroblastic proliferation within a primary or more rarely secondary hyperparathyroidism. They are named after their typical brown hemorrhagic stroma with its also typical giant cell formations.We report the case of a 31-year-old pregnant patient with a rapidly growing tumor of her left maxilla whose first symptoms during pregnancy mimicked chronic sinusitis.After swelling of the cheek, diplopia, and recurrent epistaxis appeared, she was referred to our Department for further diagnostics.After CT scan, biopsy was performed under the presumption of a malignant process with the surprising histological result of a reparative giant cell granuloma. At the same time, hyperthyroidism and nodular goiter were diagnosed and further endocrinological examinations were planned.Not until a parathyroid adenoma was diagnosed after urgent operation of the maxillary process (loose molar teeth and displacement of the left bulbus) could the tumor be interpreted and detected within this context of primary hyperparathyroidism as a brown tumor.The brown tumor should be taken into consideration as a rare differential diagnosis of a bone-destroying process of the facial bones.We discuss the clinical signs, diagnostics, and therapy for this case as well as the relevant literature. The reparative giant cell granuloma represents an important differential diagnosis and cannot be distinguished from a brown tumor by histological examination or radiological findings without complete information about the clinical signs and the endocrinological status of the patient.