Type of Preparation: SurePath/ LBP Magnification: Medium Clinical History: 35 year old Interpretation: HSIL Cytomorphologic Criteria: On low magnification, this large "hyperchromatic" cluster of cells displays enlarged nuclei and a high nuclear to cytoplasmic ratio. The dense cytoplasm suggests a squamous origin. The pattern is consistent with CIS. Explanatory Notes: As in conventional smears, crowded hyperchromatic cell groups should be examined with care. If a squamous abnormality is suspected, a thorough search for single dysplastic cells in the background is warranted. SIL occasionally presents morphologically as spindle cells. Follow-up: Biopsy-CIN 3 (severe dysplasia/carcinoma in situ)