Invasive stratified mucin-producing carcinoma (ISMC) of uterine cervix: description of pathological findings and prognosis factors in a series of 15 Chinese patients

Purpose Invasive stratified mucin-producing carcinoma (ISMC), an invasive form of stratified mucin-producing intraepithelial lesion (SMILE), is a newly named human papillomavirus (HPV) associated mucous adenocarcinoma of cervix. We aim to provide more clinical and pathological data for this uncommon disease. Methods Fifteen cases diagnosed as ISMC in our hospital were included, and their clinical and pathological data were retrospectively analyzed. Results The patients' median age was 43 years (range, 30-54 years). The most prevalent symptom was abnormal vaginal bleeding. HPV test indicated high-risk HPV in all of our 15 cases. In addition, we observed several other architectural patterns of ISMC, including nest, gland-forming or lumen-forming, papillary with extravasated pools of mucin and solid. Immunohistochemically, all of our ISMC cases showed block-like expression of P16 and diffuse positive expression of CK8 and CK18, while P63, P40 and CK5/6 were spotted positive, or completely negative. Most importantly, ISMC has a relatively high lymph node metastasis rate of 33%. Conclusions ISMC is a special type of HPV-associated adenocarcinoma, displaying a wide morphologic spectrum combined with a unique immunohistochemical profile. Clinically, ISMC may have a higher rate of lymph node metastasis, which suggests more attention to postoperative follow-up.