Fig. 14.

IgG4-related hypophysitis. Pituitary cells (asterisk) are overrun by a dense lymphocytic and plasma cell infiltrate (left image, arrowhead). IgG4-expressing plasma cells are numerous (right image). The illustrated tissue section is roughly 0.32 mm² of size, corresponding to the field area of a high-power objective lens with a 0.64-mm field diameter. In this case, there was no evidence of IgG4-related disease in other organs of the patient, leading to the classification as certain primary IgG4-related hypophysitis. Scale bar is 100 µm