Parathyroid cyst- missed diagnosis or a misdiagnosis: A case report

Introduction: The neck swellings, specially of cystic nature, may be of thyroid origin, thymic cysts, thyroglossal duct cysts, branchial cleft cysts, bronchogenic cysts or lymphangiomas depending upon the site of origin. Parathyroid cysts constitute 0.5-1% of all neck cysts and are a rare entity. A strong index of suspicion is required for its correct diagnosis. Here, we report a case of parathyroid cyst in a 40 year old female and the clinicopathological findings which posed a diagnostic challenge, thus highlighting the importance of including parathyroid cysts in the differential diagnosis of neck cysts. Case Report: Fine needle aspiration was performed on the swelling and approximately 20 ml of watery, crystal clear fluid was aspirated from the cyst. Cytological examination was acellular. The fluid PTH level was 23.6 pg/ml, serum calcium was 8.6 mg/dl (normal reference range 8.5-10.1 mg/dl) and serum PTH level was 65.88 pg/ml (normal reference range 15-65 pg/ml. Conclusion: Parathyroid cysts are uncommon benign cystic lesions and may be functional or non functional in nature. FNA is a valuable diagnostic tool along with fluid PTH level. The parathyroid cysts should be included in the differential diagnosis of all anterior cystic neck swellings so that they are not missed or misdiagnosed as thyroid lesions.