Near-infrared autofluorescence pattern in parathyroid gland adenoma

Parathyroid gland (PG) surgery is often challenging due to the small size and indistinct nature of these glands. The introduction of intraoperative near-infrared autofluorescence (NIRAF) has shown promise in localizing parathyroid tissue. However, the NIRAF features of parathyroid adenomas remain unclear. The aim of this study is to assess the NIRAF pattern of parathyroid adenomas.

Patients who underwent surgery for primary hyperparathyroidism at the University Hospital of Pisa, Endocrine Surgery Unit, between December 2021 and February 2022 were enrolled in this study. Intraoperative NIRAF patterns of suspected parathyroid adenomas were evaluated, with particular attention given to the presence of a bright cap.

A retrospective study was conducted on 11 patients with primary hyperparathyroidism who underwent parathyroidectomy at our institution. Histopathological examination of the 15 resected specimens confirmed 14 parathyroid adenomas (12 chief cell parathyroid adenomas, 1 oxyphil cell parathyroid adenoma, and 1 mixed cell parathyroid adenoma) and one schwannoma. All adenomas exhibited a heterogeneous NIRAF pattern, distinct from the homogeneous pattern observed in the schwannoma. A bright cap was identified in 9 out of 14 (64.3%) parathyroid adenomas (all chief cell adenomas). On the contrary, all 9 macroscopically normal PGs identified during surgery presented an homogeneous pattern.

Our findings support the integration of NIRAF into parathyroid surgical procedures. The heterogeneous NIRAF pattern observed in parathyroid adenomas, often accompanied by a bright cap, offers a promising intraoperative diagnostic tool to differentiate hyperfunctioning from normal parathyroid tissue. Larger-scale randomized trials are warranted to further validate these findings.