My exam experience only, histo was tested conceptually, similar to what you would see in UWorld. An example (not on my exam) would be to show you someone with chronic bronchitis and asking which layer would show an increased Reid index. Or showing you a koilocyte and asking the mechanism behind what you are seeing. I would guess about 2/3 of questions had some form of image like US, CT, Xray, angiography, micro bugs, lesion etc. Make sure you know what each of the micro bugs look like...I had like 6-7 on mine where you had to know what you were looking at just to answer the question. Anytime you come across a bug during your studies, look it up on google and an make anki deck of the pictures