A fine-needle aspiration of one lesion in the left breast is performed. What is the correct code for this procedure?

The correct code for a fine-needle aspiration of a breast lesion is 19100. This code specifically applies to the aspiration of a cyst or lesion in the breast, which aligns precisely with the procedure described in the question.

The other options reflect different procedures that either do not involve a fine-needle aspiration specifically or pertain to different regions or types of tissue. For instance, code 19101 refers to aspiration of multiple lesions, while codes like 10021 pertain to more generic aspirations that are not breast-specific. Code 19120 represents a different surgical procedure, specifically related to excision rather than aspiration. Thus, when considering the specific service of fine-needle aspiration performed on one lesion in the breast, 19100 is the appropriate and correct choice.