This is your chance to promote yourself despite your flaws. Your answer should point out a salvageable weakness. Admit that you're imperfect but will work on your weakness because you are committed to being the best you can be as a pathologist in training and practice. Remember that your team of interviewers will see right through any response that implies that you don't have any shortcomings.

"I feel that my greatest weakness coming into an esteemed pathology residency program like yours is a lack of direct lab and pathology experience. As with most medical students, our limited time in required rotations within pathology is minimal. But over the last year, I used an elective month to rotate in pathology again with an amazing preceptor. I know I'm at the same point as any potential resident you have matched in the past, but I'd make it my goal to be a great learner and consistent performer if I'm fortunate enough to match here."