TDC are common in clinical practice, while PC are rare, and are easily misdiagnosed as thyroid cysts. When the embryo develops to the sixth week, the thyroglossal duct degenerates on its own, leaving only a shallow depression at its starting point, the cecum. If the degeneration of the thyroglossal duct is incomplete during this process, the remaining epithelium may form a thyroglossal duct cyst in the course of the anterior median neck from the base of the tongue to the thyroid. The pathogenesis of PC is still unclear, but the pathogenic factors currently considered include: (1) the third or fourth pharyngeal sac remains during embryonic development [6]; (2) the residual Kursteiner’s canal develops; (3) the fusion of microcysts [7]; ④ hemorrhage or degeneration of parathyroid adenoma [8]; ⑤ parathyroid secretions are retained in vesicles [9]. Most scholars support the first hypothesis, because the third or fourth pharyngeal sac can form cysts during embryonic development, and such cysts are characterized by thin walls and transparent fluid inside, while other hypotheses form cysts with thick walls, the cyst fluid is bloody or purulent. In this case, both thyroglossal duct cysts and parathyroid cysts were combined, and the patient had a history of congenital malformations such as primary iris cysts, which further indicated that there was a correlation between the embryonic origins of these three diseases.
The classic Sistrunk procedure is currently the preferred method for the treatment of thyroglossal duct cyst, which significantly reduces the postoperative recurrence rate [10, 11]. The treatment of NPC has not yet been finalized. The current treatment methods include puncture aspiration or absolute ethanol ablation, surgical resection, and regular review. Surgical resection has gradually become the mainstream method for the treatment of NPC. The traditional anterior cervical approach surgery can completely remove the cyst and relieve the compression symptoms of the patient, which is a safe and effective treatment method [12, 13]. In this case, no recurrence was found in the 1-year follow-up after surgical resection.