[Brown tumor due to hyperparathyroidism secondary to chronic kidney disease: A clinical case].

Background: Brown tumors are aggressive and lethal due to their osteolytic capacity. They occur in 1.5 to 1.7% of patients with secondary hyperparathyroidism. The objective is to present the unusual case of an adolescent with stage V chronic kidney disease (CKD) who developed a brown tumor at the angle of the mandible due to secondary hyperparathyroidism. Clinical case: A 14-year-old female with stage V CKD of 4 months of evolution. She came to the consultation because 3 months earlier she had developed a tumor at the level of the lower left second molar which caused an increase in volume in the cheek and ipsilateral facial asymmetry, as well as occasional mild bleeding due to biting. The tumor was identified at the level of the aforementioned molar, measuring 3 cm in diameter, firm, non-mobile, and not painful to palpation; it also showed enlargement of the ipsilateral mandibular angle. Computed tomography of the mandibular angle showed a locally aggressive, solid lesion that expanded the cortex and eroded to extrude into soft tissue. A biopsy identified giant cell granuloma. Secondary hyperparathyroidism and subclinical hypothyroidism were detected; pharmacological management was initiated, with an adequate tumor's response. Conclusions: Brown tumors are very rare as the first clinical manifestation of secondary hyperparathyroidism in pediatric population. If a giant cell tumor is present in patients with CKD, brown tumor should be ruled out.