SAT-374 The Many Faces of Parathyroid Carcinoma in the Philippines: A Case Series

Introduction: Parathyroid carcinoma is rare, affecting less than 1% of patients with primary hyperparathyroidism (PHPT). (1) Parathyroid carcinoma with concomitant papillary thyroid carcinoma is also rare, and the etiology is not fully defined. Clinical Case: We present 3 patients with parathyroid carcinoma and discuss their presenting symptoms, characteristics, and treatment. Two women and 1 man (2 Filipinos and 1 Marshallese) with age range 53-68 years old had parathyroid carcinoma. Two had primary hyperparathyroidism, one had non-functioning type of parathyroid carcinoma. Two had concomitant bone or renal disease. All three had concurrent thyroid disease- 2 had papillary thyroid microcarcinoma, one had colloid goiter. Because each one had different indications for neck surgery, different surgical techniques were done. Parathyroid cancer size ranged from 2.0-5.2 cm, with capsular and vascular invasion in all three. One case had double parathyroid carcinoma. No lymph node metastasis was identified. On follow up, the patient with the largest tumor size had tumor recurrence within 1 year from surgery. Conclusion: To the best of our knowledge, this is the first case series on parathyroid carcinoma in the Philippines, and includes the 7(th) case of double parathyroid carcinoma worldwide. Parathyroid carcinoma is a rare condition, and coupled with its highly variable presentation, as seen in the 3 cases, presents clinicians with a difficulty in arriving at a diagnosis. Histopathology remains the gold standard in diagnosis and is a key in guiding management. Since coexisting thyroid and parathyroid disease may occur, thyroid pathology should be evaluated in the presence of PHPT. References: 1. Elizabeth Shane; Parathyroid Carcinoma, The Journal of Clinical Endocrinology & Metabolism, Volume 86, Issue 2, 1 February 2001, Pages 485-493, https://doi.org/10.1210/jcem.86.2.7207.