A case of a cervical cyst due to congenital pyriform sinus fistula in a neonate

We present the case of a female infant born at 38 weeks of gestation at our medical facility, displaying signs of a suspected lymphatic cyst in the left neck region. The infant had Apgar scores of 8 and 9 at 1 and 5 min after birth, respectively. A palpable mass was noticed in the left neck area, but there were no signs of respiratory distress. Imaging of the neck revealed the presence of air within the cyst, suggesting a connection to the gastrointestinal tract (Figure 1a). Cystography revealed a fistula connected to the pyriform sinus (Figure 1b). At 8 days of life, the size of the tumor had increased, accompanied by an inflammatory response (Figure 1c). A cystic puncture detected methicillin-resistant Staphylococcus aureus infection. Antibiotics were administered, and a cystectomy was scheduled. The platysma muscle was separated during the surgery through a collar-like incision, and the cyst was identified immediately beneath the sternocleidomastoid muscle. Adhesions along the cyst wall were dissected, and the left upper pole of the thyroid gland containing the cyst was excised. The recurrent laryngeal nerve was not exposed. Indigo carmine staining identified a fistula in the hypopharyngeal constrictor muscle, and the cystectomy was completed (Figure 1d). Pathological examination revealed a pseudostratified ciliated epithelium in the cyst and showed the thymus and thyroid, suggesting a pyriform sinus (Figure 1e,f). Informed consent was obtained from the patient's parents, and the case report was approved by the ethics committee of our hospital (Approval No. B0516). Congenital pyriform sinus fistula (CPSF) was first reported in 1973 by Tucker and Skolnick.1 CPSF typically presents as a recurrent anterior neck mass or abscess in children but occasionally as a cervical cystic lesion in neonates. The differential diagnoses of cervical cysts in neonates include lymphangioma, lateral cervical cyst, branchial cyst, esophageal duplication cyst, teratoma, dermoid cyst, bronchogenic cyst, and thyroid tumors. In our case, prenatal magnetic resonance imaging (MRI) suggested the mass was a lymphangioma, whereas postnatal MRI and computed tomography (CT) indicated an esophageal duplication cyst or CPSF because the cyst contained gas and fluid, suggesting a connection to the pharynx and esophagus. Ultrasonography, gastrographin esophagography, and laryngoscopy following MRI and CT failed to reveal the fistula extending from the cyst; therefore, we performed retrograde cystography using cystic puncture and successfully detected the tract originating from the pyriform sinus. Since visualizing the fistula may be difficult in neonates, this method is useful for determining the characteristics and diagnosis of the cyst. Neonates with CPSF present with stridor and acute respiratory distress caused by airway obstruction, requiring early surgical treatment. In this case, the cyst gradually increased in size, and inflammatory reactions slightly increased; therefore, surgery was performed at 1 month of life. CPSF surgery requires complete resection of the fistula and cyst; incomplete fistula resection can lead to a recurrence. Various surgical or endoscopic techniques have been reported to prevent recurrence as follows: cannulation with Fogarty catheter or a guidewire before surgical excision,2 staining during surgery (as performed in our case), transoral endoscopic resection of the fistula,3 endoscopic electrocauterization,4 and chemical cauterization of the fistula opening.5 A study that compared open neck surgery for tract excision and endoscopic cauterization of the sinus tract opening showed that the complication rates were 5% and 0%, respectively, and the recurrence rates were 15% for both, without significant difference.5 Moreover, in another report, chemical cauterization caused vocal cord paralysis, indicating that proficiency is required for proper cauterization using an endoscopic technique. We selected open-neck surgery and injected dye into the cyst without performing laryngoscopy or cannulation because identifying the tract orifice from the oral cavity may be difficult in neonates. In addition, we considered that the pyriform sinus cyst could not be completely cured by cauterization of the fistula opening. Although the superior laryngeal nerve could not be identified during surgery, we detected the fistula safely and successfully resected the CPSF. In conclusion, therapies for preventing CPSF recurrence in neonates remain controversial. In our case, early surgical resection of the CPSF provided effective treatment without complications or recurrence. Long-term follow-up may be required in cases receiving each treatment. M.O., S.T., R.I., and F.Y. performed the surgery. K.I. managed the patient after the surgery. All authors have read and approved the final version of the manuscript. We appreciate Yuko Nakamura and Yuka Nomura for the data collection. The authors declare no conflict of interest.