Figure 3: A panoramic radiograph obtained one year after the intervention demonstrated a significant reduction in the size and radiolucency of the previously observed mandibular lesion, suggesting successful treatment.
Discussion :
As found in the literature, brown tumors target a rather young population, with a highest incidence between 30 and 60 years old with female predilection, ration 2/3.3,4 The predominant clinical manifestation is facial swelling which can be painful or painless. 5 When the mandibular lesion is not yet externalized, the discovery is then fortuitous as in our case. Brown tumors most often have many locations, particularly in the long bones such as the femur, tibia, clavicle, ribs and appear more rarely at the maxillofacial area.6 When they develop in the facial region, the most affected bone is the mandibular bone, as in the case reported.5,7 Bone demineralization is caused by hypersecretion of PTH, PTH stimulates osteolysis which allows the release of calcium into the blood. Primary hyperparathyroidism is caused by gland adenoma in 80% of cases. Secondary hyperparathyroidism is related to chronic renal failure or vitamin D deficiency. Tertiary hyperparathyroidism is caused by a long standing non treated secondary hyperparathyroidism leading to parathyroid hyperplasia. Diagnosis of maxillary bone lesions caused by hyperparathyroidism is based on clinical, radiological, biological and anatomopathological examinations.6,8 Panoramic X-ray is a two-dimensional dental X-ray examination that shows maxilla mandibular structures and lesions. It can show fortuitously bone demineralization or well-defined bone radiolucency. Cervical ultrasound when hyperparathyroidism is suspected, can show adenoma or hyperplasia of the gland. Scintigraphy on MIBI is indicated in case of ectopic and posterior adenoma. Biological examination usually shows hyperparathyroidism associated to:
- Hypercalcemia and hypophosphatemia for Primary HPT
- Hypocalcemia and hyperphosphatemia for Secondary HPT
- increased alkaline phosphatase in both cases
The case reported here presented hyperphosphatemia (1.70 mmol/l) which is in favor of secondary hyperparathyroidism. The pathological examination with biopsy of the tumor was not carried out because there was no indication for surgical intervention for this patient. Regarding dental condition in the injured area, dental displacements and / or dental mobility due to the loss of the lamina dura, as well as bone lysis in the periapical region can be observed, in our patient the lesion was discovered at an early stage with absence of tooth mobility. The evolution and resolution of the brown tumor will be more or less rapid depending on the importance of the bone demineralization as well as the tumor localization. Either a resolution without sequelae (disappearance of mobility) or an early loss of teeth will be observed.4,5 A loss of teeth vitality related to the lesion and/or canals calcification are also observed, which can lead to a clinical misdiagnosis and erroneous management consisting of antibiotics prescription or endodontic treatment. 2The characteristics of the brown tumor are as follows:
- Macroscopic appearance: hard nodular type lesion, firm on palpation, with or without ulcerated oral mucosa, gray/brown in color, and haemorrhagic.9,10
- Microscopic appearance: it is a fibrous tissue composed of fibroblasts, multinucleated giant cells,surrounded by a stroma composed of numerous blood vessels with clusters of macrophages filled with deposits of hemosiderin and hemorrhagic areas.9,10
- Radiological aspect: radiolucent osteolytic lesion, uni or multilocular with defined contours, without invasion of the adjacent structures bone remodeling zones can be observed associated to significant osteoclastic activity.9,10
Loss of cortical bone and lamina dura at the level of the affected teeth may occur in more locally aggressive forms.1,6 Brown tumors treatment begins with the resolution of the hyperparathyroidism to hope for the tumor’s resorption and, if necessary, perform a secondary mass excision.3,6,8,9 Total or subtotal parathyroidectomy is indicated especially in cases of hyperplasia or parathyroid adenoma depending on the number of glands affected, as is the case with our patient, the bone lesion spontaneously regressed after normalization of the constants, a control X-ray panoramic after one year is recommanded to objectify the regression of the lesion
In cases of secondary hyperparathyroidism, its resolution requires renal therapy (graft, renal transplantation, hemodialysis) and/or calcium and vitamin D supplementation.7