6858 Robot-Assisted Surgery of Mediastinal Intrathymic Parathyroid Adenoma: A Case Report

Abstract Disclosure: F. Jovanovic: None. V. Jovanovic: None. M. Khan: None. S. Fletcher: None. Background: Ectopic foci of parathyroid tissue pose a diagnostic challenge and lead to a delay in patient care. We present a case report of intrathymic parathyroid adenoma with successful removal using robot-assisted surgery. Case Report: A 33-year-old female with past medical history of gastroesophageal reflux disease, depression, and chronic anemia was found to have hypertension during her third trimester prenatal visit. The patient was complaining of fatigue, abdominal discomfort, and constipation. Laboratory results showed elevated serum calcium 11.3 mg/dL (7.9–10.6), albumin 2.7 gm/dL (3.4–5.0), corrected calcium 12.3 mg/dL (7.6–10.6), and parathyroid hormone (PTH) 122 pg/mL (14–72). A year after childbirth, she continued to experience these symptoms with persistent hypercalcemia and no etiology identified. As part of diagnostic workup, the patient underwent computed tomography (CT) with and without (WWO) contrast of the neck and sestamibi parathyroid scan, both of which were unremarkable. The patient was then referred to a tertiary hospital for a technetium 99m sestamibi followed by single-photon emission computed tomography (SPECT) imaging of neck and chest, which showed scintigraphic findings suspicious of ectopic parathyroid adenoma in the upper mediastinum. Over the next few months, the patient underwent SPECT imaging and 4D helical CT WWO contrast of the neck and thorax that showed 1cm ectopic parathyroid adenoma within the left thymic lobe, at the level of the top of the pulmonary artery arch and upper ascending aorta proximal to the arch. Upon patient’s admission to a quaternary medical center, her lab work showed serum calcium 11 mg/dL and PTH 237 pg/dL. The decision was made to proceed with surgical resection of intrathoracic parathyroid adenoma using robot-assisted (da Vinci® Surgical System) thymectomy. Histopathology analyses of surgery specimens were consistent with parathyroid adenoma and benign thymic tissue. The patient’s lab work on the following day showed significant improvement with serum calcium 8.5 mg/dL and PTH 30.9 pg/mL. While literature review acknowledges intrathymic location of ectopic thyroid1, research on minimally invasive surgical approach involving this pathology is scarce. Upon surgery, the patient reported full resolution of her symptoms. Conclusion: Persistent hypercalcemia in the setting of unrevealing parathyroid adenoma should prompt suspicion for ectopic parathyroid location. Robot-assisted thymectomy poses a minimally invasive surgical approach in diagnosing and treating mediastinal intrathymic parathyroid adenoma. References:1.Abraham BM Jr, Sharkey E, Kwatampora L, Ranzinger M, von Holzen U. Mediastinal Intrathymic Parathyroid Adenoma: A Case Report and Review of the Literature. Cureus. 2023 Jul 22;15(7):e42306. Presentation: 6/2/2024