Background: Calcified lymph nodes (LNs) on computed tomography (CT) in patients with lung cancer are generally considered to be a benign feature. However, few studies have evaluated the pathological status of such calcified LNs. We investigated the clinicopathological findings of patients with calcified LNs on preoperative CT who underwent operation for lung cancer and assessed the frequency of metastasis to calcified LNs as well as the risk factors associated with such metastases. Methods: This was a retrospective study of 72 consecutive patients with calcified LNs detected on preoperative CT who underwent pulmonary resection for primary lung cancer between 2011 and 2013. A total of 354 LN stations including 101 LN stations with calcified LNs were evaluated. Results: The frequency of metastasis to calcified LNs was 19.4% (14 of 72 patients) on a per-person basis and 18.8% (19 of 101 stations) on a per-nodal station basis. When the size of calcification was major (>5 mm), the frequency of metastasis to such calcified LNs was significantly lower than when it was minor (≦5 mm) on a per-nodal station basis (11.1% vs 27.7%, P = 0.043). Furthermore, when the size of calcification was major and the status of LN stations with calcified LNs was single, there was no metastasis to such LN stations (0 of 26 stations). Conclusions: The frequency of metastasis to calcified LNs was about 20% on both a per-person and a per-nodal station basis. Although calcified LNs as well as non-calcified LNs should be dissected during operation, dissection of a single LN station with calcification, particularly major calcification, can be omitted.
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