In cases of adenocarcinoma in situ, there are usually a larger number of atypical glandular cells that form crowded cellular clusters (Figure 40).
The sheets are usually three-dimensional. The cells within these sheets occasionally form rosettes and have extensive feathering of the cells at the periphery. Individual endocervical cells are highly atypical with enlarged round, oval or elongated nuclei that vary in size from cell to cell. In most cases, the chromatin is coarsely clumped and multiple mitoses are seen.