Sixty six patients with MEN1-related HPT who underwent initial neck exploration with TCT from 1993 to 2007 were identified and their charts retrospectively reviewed. These patients were admitted to the NIH under an IRB approved clinical protocol and all gave informed consent. We defined MEN1 HPT as occurring within a known MEN1 kindred or in a patient with pancreatic and/or pituitary lesions.
Demographic information, signs and symptoms at presentation or screening, and duration of symptoms when present were collected. Information regarding kindred, mutational status, and other manifestations of MEN1 were collected as were pre- and post-operative serum and ionized calcium values, pre-, intra-(when available), and postoperative parathormone values. Data regarding the types and results of pre-operative tumor localization studies were also collected.
All peri-operative data, operative notes, and pathology reports were reviewed for the number of glands the surgeon found in the neck exploration and the thymectomy specimen. The current NIH preference at an initial operation for these patients is a transcervical incision and subtotal (3.5 gland if four glands are found) resection without fresh parathyroid autotransplantation.15
All patients underwent transcervical thymectomy. Thymic tissue is identified on both sides of the neck and dissected in a substernal manner in order to resect as much thymic tissue as possible down to the inominate and below if it can safely be removed via the collar incision. This typically results in removal of an estimated 30–40% of the thymus. Pathology reports were also reviewed for the presence of any carcinoid tissue in thymectomy specimens. Follow-up data were obtained when available.
For the purpose of analysis, we divided the patients into two groups. The first group consisted of patients in whom four glands were found during the neck exploration and before TCT was performed, and the second group consisted of those patients in whom gland(s) were still unaccounted for prior to TCT. The yield of additional parathyroid and any carcinoid tissues as well as recurrence data were compared between these groups.
These groups were also compared with respect to pre-operative data. A chi-squared test or Fisher’s exact test, as appropriate, was used to compare dichotomous characteristics. Counts of signs, symptoms, or signs plus symptoms were compared between the groups using an exact Cochran-Armitage test for trend.16
The distribution of kindred vs. lesion vs. both was compared between groups using Mehta’s modification to Fisher’s exact test.17
Continuously distributed parameters were compared between groups using a Wilcoxon rank sum test since many parameters were not normally distributed. All p-values are two-tailed and have not been adjusted for multiple comparisons.