Endocrine Abstracts

Giant cell tumors are rare, benign but aggressive and locally invasive tumors that usually affect the long bones in the limbs, typically presenting during the 3^rd or 4^th decade of life. Giant cell tumors of the skull are exceedingly rare, and less than 150 cases have been reported to date, of which less than 10 were described in the pediatric population. Here, we present the case of a 14 year old female that progressively developed severe headaches, blurry vision and diplopia over approximately 4 months. She was initially directed to the Neurosurgery service, where imaging studies revealed a mass, initially presumed to be a craniopharyngioma, on the left cavernous sinus topography, that extended into the sella turcica and compressed the pituitary. Complete resection was impossible due to the close proximity of the mass with the internal carotid artery, so endoscopic transnasal partial resection and a biopsy were performed instead. Histopathological examination along with immunohistochemical staining suggested that the mass was a pituitary adenoma. Endocrinological examination revealed partial corticotroph and tireotroph insufficiency, and substitution treatment with hydrocortisone and levothyroxine was initiated, but the patient was non-adherent. Over the next 6 months, the patient’s symptoms worsened, and she was readmitted to the Neurosurgery service, where imaging studies showed the remaining mass had grown to 3 centimeters maximum diameter. A second endoscopic transnasal partial resection and biopsy were performed. Second biopsy results suggested a giant cell tumor, but recommended determining PTH levels to rule out a brown tumor. Subsequent endocrinological examination revealed moderately elevated PTH levels (124 pg/ml), and vitamin D deficiency (serum vitamin D=10.32 ng/ml). PTH levels normalized (64.9 pg/ml) after 6 months of vitamind D treatment (2000 IU daily). Giant cell tumors of the skull bones are exceedingly rare, especially in the pediatric population, but should still be considered in the differential diagnosis of sellar and parasellar masses. This case report is an opportunity to go over the impact of this type of tumor on quality of life, the differential diagnosis process, as well as the therapeutic options and their indications and contraindications in the adult and pediatric population.