Type of Preparation: SurePath/ LBP Magnification: High Clinical History: 44 year old woman Interpretation: HSIL Cytomorphologic Criteria: Such ?hyperchromatic crowed groups? may raise a wide differential diagnosis under low magnification; attention to architectural pattern and cellular detail are necessary for correct interpretation. In this image, the enlarged nuclei with hyperchromatic/granular chromatin, dense cytoplasm and high N/C ratio cells arranged in a syncytial cluster such as this warrant an interpretation of HSIL/CIS. Explanatory Notes: The nuclei in this tightly arranged group are too large to be endometrial cells. Other differential diagnosis of such "hyperchromatic clusters" include atrophy/ parabasal cells, lower uterine segment, glandular epithelial abnormalities and HSIL extension into endocervical gland spaces. Follow-up: Biopsy- CIN 3 (severe dysplasia/CIS)