Ectopic parathyroid adenomas located at the cervicothoracic junction pose a surgical challenge. Their deep location, scarcity of reliable anatomical landmarks, and frequently limited or discordant preoperative imaging may hinder intraoperative identification and lead to more invasive surgical approaches.

Near-infrared autofluorescence (NIRAF) is increasingly used for intraoperative identification of parathyroid tissue. Probe-based devices such as PTeye® have shown high accuracy for identifying eutopic glands [1,2] and provide immediate, label-free, radiation-free detection [3]. However, autofluorescence in hyperfunctioning glands may be more heterogeneous and weaker than that observed in normal parathyroid glands [4]. A recent multicenter randomized trial confirmed that probe-based NIRAF improves parathyroid identification during endocrine neck surgery [5], but evidence regarding its use in deeply located ectopic cervicothoracic adenomas remains limited.

We reviewed a total of 6 consecutive patients with primary hyperparathyroidism caused by an ectopic parathyroid adenoma who underwent surgery with PTeye® guidance over an 18-month period. The adenomas were located in the deep retrotracheal space in 2 patients, the retroesophageal space in 2, the low paracarotid region in 1, and the upper mediastinum with cervical accessibility in 1. Preoperative technetium Tc 99m-sestamibi single-photon emission computed tomography/computed tomography correctly localized the adenoma in all 6 patients. None of the procedures were reoperations, and all were performed by the same surgeon. In none of the cases was the gland visible after the cervical incision; nevertheless, all adenomas were resected through a minicervicotomy without sternotomy or a combined surgical approach.

PTeye® guided dissection toward parathyroid tissue before the adenoma was directly exposed. Near-infrared light, with an excitation wavelength of approximately 785nm and an emission wavelength of approximately 820nm, undergoes less scattering and absorption than visible light. In addition, the contact probe can access confined retrotracheal and retroesophageal planes. Consequently, the autofluorescence signal could be detected through overlying tissue, enabling subsurface localization of concealed glands, unlike line-of-sight imaging systems. The autofluorescence pattern was homogeneous in some adenomas and heterogeneous, with brighter peripheral areas, in others [4]. The small sample size precluded assessment of associations between autofluorescence patterns and histological features, adenoma size, or depth; therefore, these findings should be considered hypothesis-generating.

Intraoperative parathyroid hormone (PTH) levels were measured at baseline and 10min after excision, with biochemical cure defined according to the Miami criterion. Mean serum calcium decreased from 11.8mg/dL (range, 10.9–12.5mg/dL) before surgery to 9.48mg/dL (range, 8.5–10.3mg/dL) 1 month after surgery. Mean PTH decreased from 141.5pg/mL (range, 90–276pg/mL) to 30.48pg/mL (range, 18.9–53pg/mL). All postoperative values were within the reference ranges, and no patient developed hypocalcemia. At a median follow-up of 12 months (range, 8–15 months), all patients remained normocalcemic and had normal PTH levels.

No intraoperative frozen-section analysis was performed; therefore, parathyroid tissue was confirmed only by final histopathological examination, which demonstrated an adenoma in all 6 cases. This represents a limitation of the study. No complications occurred. The longer operative time in the patient with the mediastinal adenoma, 70min, reflected the greater depth and complexity of the required dissection. The detection ratio, defined as tissue autofluorescence normalized to the thyroid baseline and considered positive at values>1.2 [2], ranged from 1.5 to 1.8 (Table 1).