Histologic Hypercellularity In A Biopsied Normal Parathyroid Gland Does Not Correlate With Hyperfunction In Primary Hyperparathyroidism
Kelly L McCoy, Linwah Yip, *Mashaal Dhir, *Kristina M Langenborg, *Raja R Seethala, Sally E Carty
University of Pittsburgh, Pittsburgh, PA
Objective: About 15% of patients with sporadic primary hyperparathyroidism (PHP) have multigland disease (MGD). During resection of an apparent single adenoma, a visibly normal parathyroid (NG) may be easily identified and biopsied to help compare gland weights and deduce MGD. In a cohort of patients with very long-term follow-up, we examined whether hypercellular NG histology correlates with unrecognized MGD and subsequent PHP recurrence.
Methods: This was a single-surgeon review of all patients who from 2001-15 had initial exploration for sporadic PHP with removal of a single adenoma, routine NG biopsy, intraoperative parathyroid hormone monitoring, and f/u of at least 3 years. Cure was defined by eucalcemia at 6 months, and recurrence by hypercalcemia arising after documented cure. Hypercellularity was defined by histologic predominance of chief cells and oxyphils with <30% stromal fat. NG cellularity was compared with long-term biochemical outcomes.
Results: Among 134 patients with mean f/u 9.4 y (range 3.1-15.9), 132 (98.5%) exhibited cure at 6 months, 2 patients had initial failure (each with a normocellular NG), and 8/132 (6.1%) went on to recur (mean time to recurrence 5.8 y, range 4-10.6). The biopsied NG was hypercellular in 14/132 patients with long-term cure (10.6%). The likelihood of NG hypercellularity did not differ for patients with long-term cure (12/124, 9.7%) versus recurrence (2/8, 25%, p=0.2) (Figure 1). The PPV of NG hypercellularity for recurrence was low at 14.3%, and the NPV of NG hypercellularity was high at 94.9%.
Conclusions: During initial surgery for PHP, 10% of biopsied normal parathyroid glands are hypercellular, but the finding does not signify missed multiglandular disease. In contrast, normocellularity of a biopsied NG has a high predictive value for durable cure (95%). In addition, with an observed 6% rate of late recurrence after apparently curative surgery for sporadic PHP, we suggest yearly calcium assessment for all patients as recurrences can occur years after initial curative parathyroidectomy.
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