Metastatic lymph nodes in hilar cholangiocarcinoma: does size matter?

To determine the diagnostic efficacy of the size criteria for the detection of metastatic lymph nodes (LN) in patients with hilar cholangiocarcinoma (HCCA).

LN metastasis is one of the most significant independent prognostic factors in patients with HCCA. Presently, in spite of the well known lack of sensitivity and specificity, one of the most used clinical criteria for nodal metastases is LN size.

Pathological slides of 147 patients who had undergone exploration for HCCA were assessed. The size (maximum and short axis diameter) of each single node was retrieved from the pathology report or measured from a section on the glass slide using a stereo microscope and a calibrated ruler integrated in the software. When a metastatic lesion was detected, the proportion of the lesion in relation to LN size was estimated.

Out of 147 patients, 645 LN were retrieved and measured. In all, 106 nodes (16%) showed evidence of metastasis. The proportion of positive nodes was 8% in nodes <5 mm and 37% in nodes >30 mm. Ten per cent of LN smaller than 10 mm were positive, whereas only 23% of LN larger than 10 mm were metastastically involved. No clear cut-off point could be found. Similar results were found for the short axis diameter. In 50% of positive LN, the metastatic lesion accounted for 10% or less of the LN size.

No cut-off point could be determined for accurately predicting nodal involvement. Therefore, imaging studies should not rely on LN size when assessing nodal involvement.