Information regarding biopsies?

I'm getting another potential melanoma removed, this time off my chest, and I was wondering if it is cancerous and they have to test my lymph nodes, how would they do that since the nearest lymph node to the mole is inside my chest among my internal organs. Anyone who's been through something similar I would love to hear you're insight.

they will insert a fine needle through your skin ( probably sedate you) so you wont feel the pain to get to the lymph node tissue. Its called FNB (fine needle biopsy)

Thank you!