Non-functioning parathyroid cyst

Abstract Rationale: Parathyroid cysts are rare lesions which are classified as functioning and non-functioning, based on the hormone activity. We report an incidental finding of a non-functioning parathyroid cyst in a patient who showed good prognosis after surgery. Patient concerns: A 63-year-old female patient had a medical history of stage III chronic kidney disease, asthma, and idiopathic hypothyroidism. She underwent low-dose lung computed tomography and a suspected enlarged lymph node in the suprasternal region was identified. Diagnoses: The nodular site was considered relatively safe, thus, we did not arrange for further examinations and decided to perform a surgical biopsy intervention first. Consequently, immunohistological examination findings led to the diagnosis of parathyroid cyst. The patient's serum calcium level was normal. Thus, she was diagnosed with a non-functioning parathyroid cyst. Interventions: Surgery was performed with a 3-cm long incision on the midline of the upper chest wall for biopsy. A 19 mm × 15 mm × 7 mm cystic lesion was excised. Outcomes: No complications were observed after the surgical biopsy. The patient remains asymptomatic with no recurrence or serum biochemical abnormalities during the 1-year follow-up. Lessons: In cases of non-functioning parathyroid cysts, it is difficult to precisely diagnose it before surgery. We report a case of an incidental finding of a parathyroid cyst and the patient had a good prognosis after excision of the parathyroid cyst.