Cytologic features of stratified mucin producing intraepithelial lesion of the cervix--a case report.

Stratified mucin-producing intraepithelial lesion (SMILE) of the cervix is a human papilloma virus (HPV) associated high grade intraepithelial columnar cell neoplasm that is thought to arise from the reserve cells of the transformation zone. It is composed of immature stratified cells that display intracytoplasmic mucin and is commonly associated with high grade squamous intraepithelial lesion (HSIL), adenocarcinoma in situ (AIS), and invasive carcinoma. Here, we describe the cytologic features of SMILE and discuss its pitfalls in cervical cytology. A 51-year-old woman was diagnosed with SMILE on a cervical biopsy. Histologically, the dysplastic epithelium showed enlarged nuclei with increased nuclear density and presence of mucin-producing columnar cells throughout its thickness. The slides from the last two Pap tests (ThinPrep) performed on the patient were reviewed and compared with the histology. Cytologically, groups of atypical endocervical glandular cells were seen on both Pap tests. These groups showed mild nuclear crowding, slightly enlarged nuclei, nuclear hyperchromasia, and indistinct nucleoli. The borders of these cell groups were relatively smooth. Original cytologic diagnosis was atypical squamous cells of undetermined significance (ASC-US) in both instances. HPV (Hybrid Capture 2) testing was positive on both occasions. Similar to the histology, cytologic features of SMILE are subtle. The features are not typical for AIS or for HSIL and could easily be misinterpreted as reactive. This report emphasizes that careful review of crowded groups of glandular cells in HPV positive women is absolutely critical. Based on our knowledge, this is the first description of the cytologic features of these lesions.