Marking apparatus for marking tissue imaged through an imaging device including a viewing element in the form of a spacer having an imaging window which provides an imaging zone through which tissue can be imaged by an imaging probe. The apparatus can include a marker implement connected to a coupling device. In some embodiments, the coupling device is configurable to position the marker implement in a first position substantially out of the imaging window and a second position in the imaging zone of the imaging window. The marker implement can apply a mark when in the second position and thereby to tissue in the imaging zone while the apparatus remains in the imaging position on the tissue. The spacer can be length adjustable in order to change the depth of focus of the imaging probe, thereby to focus at different depths within a patient's skin.