The anatomical textbooks currently in use do not describe the blood vessels running on the surface of the lymph nodes.

This animation shows a lymph node of a C57BL/6J mouse.

The blood in the inner vessels flows into the surface vessels. [1]

Without proper knowledge of lymph node metastasis, we may misinterpret it.

References

[1] K. Takeda, S. Mori, T. Kodama, Study of fluid dynamics reveals direct communications between lymphatic vessels and venous blood vessels at lymph nodes of mice, Journal of immunological methods, 445 (2017) 1-9.