Type of Preparation: ThinPrep/ LBP Magnification: Medium Clinical History: 64 year old postmenopausal woman with hx of abnormal Pap test elsewhere Interpretation: Endocervical adenocarcinoma in situ (AIS) /HSIL Cytomorphologic Criteria: Hyperchromatic crowded group of AIS (upper right) and small aggregate of HSIL (lower left). Explanatory Notes: Co-existing glandular and squamous lesions should always be considered when making an interpretation of endocervical adenocarcinoma in situ. Follow-up: Endocervical adenocarcinoma in situ with invasive adenocarcinoma and HSIL