Central intranodal blood vessel: a new EUS sign described in mediastinal lymph nodes.

Background: The vascular architecture of normal lymph nodes is composed of prominent centrally located blood vessels. In malignant nodes, this pattern is distorted because of tumor infiltration and neovascularization.

Objective: To determine whether EUS imaging of central intranodal blood vessels (CIV) can be used to differentiate benign from malignant subcarinal lymph nodes in lung cancer.

Design: CIV was defined as a > or =1-mm-diameter tubular structure, with well-defined walls and blood flow. The diagnostic accuracy of CIV was compared with other lymph-node features in a retrospective cohort of patients who underwent EUS for lung cancer evaluation. Findings were then prospectively validated in a similar cohort.

Setting: Minneapolis Veterans Affairs Medical Center.

Patients: Patients who underwent EUS for lung cancer diagnosis or staging at the VA Medical Center from March 2003 to March 2005.

Results: Of 67 patients included in the retrospective analysis, CIV was noted in 17 of 35 patients with benign nodes (49%), compared with 5 of 32 patients with malignant nodes (16%) (P = .002). In lymph nodes > or =1 cm, CIV was noted in 14 of 16 patients with benign nodes (88%), compared with 2 of 27 with malignant nodes (7%) (P < .001). Forty-five patients were included in the prospective validation cohort, and 16 had malignant lymph nodes. For malignant lymph-node metastasis, the absence of CIV had a sensitivity of 75%, a specificity of 97%, and an accuracy of 89%. The accuracy of CIV was superior to that of lymph-node shape; margin; and internal echo pattern, singly or in combination.

Conclusions: The absence of a central intranodal blood vessel was a strong and independent predictor of malignancy in lymph nodes of patients with lung cancer and can be used to select lymph nodes for FNA.