Retropharyngeal Parathyroid Glands: Important Differences.

introductionIn primary hyperparathyroidism (PHPT), parathyroid ectopia is seen in up to 22% leading to more difficult surgery. We aimed to determine the rate and characteristics of retropharyngeal (RP) parathyroid glands.

methodsA prospective database was queried for patients with sporadic PHPT who had surgery from 1997 to 2016. The data of RP patients were compared to those who had surgery for sporadic PHPT over the same time period with hyperfunctioning parathyroids in anatomically normal positions (N).

resultsRP glands occurred in 47/3006 (1.6%) patients and were more common at reoperative than initial surgery (5.5 vs 1.4%, p < 0.01). RP patients had prior failed surgery more often than N patients (17 vs 3.1%, p < 0.01). Preoperative calcium levels (p = 0.06), PTH levels (p = 0.15), and mean gland weights (p = 0.07) were similar among groups. For RP glands, ultrasound imaging was negative in all but one patient, while 99mTc-sestamibi accurately indicated a posterior midline position in only 13/47 (28%) and was negative in 21%. All RP glands were anatomically superior. RP patients more often required > 1 post-resection intraoperative PTH level (36 vs 21%, p = 0.02). Failure due to persistent PHPT was more likely in RP patients (4.7 vs 2.1%, p = 0.2).

conclusionIn PHPT, hyperfunctioning RP glands are seen in 1.6% of cases and often associated with initial failure (17%). At reoperation, RP ectopia is 4X more common. RP glands are associated with a high rate of negative imaging, but imaging results suggestive of a midline abnormality can guide exploration. The RP space should be evaluated prior to ending an otherwise unfruitful surgery.