Zuckerkandl's tubercle (ZT) of the thyroid gland is a well-documented anatomical structure. This study evaluated the anatomical relationship of the ZT in terms of the recurrent laryngeal nerve (RLN) and the superior parathyroid gland (SP).

The study included 325 patients (ten patients with benign tumors and 315 patients with malignancies) who underwent thyroid surgery between February and June 2007. Tubercles were classified according to size: Grade 0 (unrecognizable), Grade I (≤ 5 mm), Grade II (6~10 mm) and Grade III (>10 mm). The incidence and size of the ZT and its positional relationship to the RLN and SP were investigated during thyroid surgery.

ZTs were identified in most patients (right thyroid 89.3%, left thyroid 85.6%). The percentageof tubercles according to grade and location was as follows: Grade 0, right thyroid 10.7% and left thyroid 14.4%; Grade I, right thyroid 7.9% and left thyroid 11.1%; Grade II, right thyroid 43.5% and left thyroid 38.5%; Grade III, right thyroid 37.9% and left thyroid 35.9%. The most common RLN course was in a groove between the ZT and the main body of the thyroid. Most of the SPs are situated cranial to the ZTs and were located at the 1 or 2 o'clock position (96.1%) in the left thyroid and at the 10 or 11 o'clock position (95.2%) in the right thyroid. A greater distance between the ZT and the SP was seen with a decreasing size of the ZT.

The ZT was identified during most thyroidectomies, and there was a constant relationship between the ZT and either the RLN or SP. Therefore, identification of the ZT and an understanding of the relationship between the ZT and either the RLN or SP are essential for the performance of safe thyroid surgery.