FIG. 3.

Endometrial endometrioid adenocarcinomas. Typical low-grade (FIGO grade 1) tumor (A) has patchy expression of p16 (B). Some tumors, regardless of grade (another FIGO grade 1 example, C) can have more extensive p16 expression but there are usually interspersed negative foci (D) so that the pattern is not fully diffuse as in a high-risk human papillomavirus–related endocervical adenocarcinoma (compare with Fig. 2A). Most higher-grade tumors (FIGO grade 2 and 3 examples) also have patchy p16 expression (E–H). Some low-grade tumors with extensive metaplastic-type differentation can have more extensive p16 expression but typically there are interspersed negative foci (I–L).