Cytological features of invasive stratified mucin-producing carcinoma of the uterine cervix and literature review.

Invasive stratified mucin-producing carcinoma (ISMC) is a rare type of cervical adenocarcinoma associated with human papillomavirus (HPV). Stratified mucin-producing intraepithelial lesion (SMILE) is an in situ glandular lesion of ISMC. Such lesions have been reported in histology, but cytologic features of ISMC and SMILE are rarely reported in previous cervical cytology. Herein, we report a case of ISMC combined with usual-type endocervical adenocarcinoma (UEA). Cytologically, most cells showed morphological features of UEA cells. Another small portion of the cells was arranged in layers or scattered individually, with rich mucin in the cytoplasm and stained light pink. The nuclei of the cells were crowded and atypical, with hyperchromasia. This study aimed to discuss the cytological features of ISMC or SMILE and emphasize that abnormal mucinous epithelial cells in HPV-positive patients should be carefully observed to avoid misdiagnosis of ISMC or SMILE.