Invasive stratified mucin-producing carcinoma: a clinicopathological analysis of three cases

Objective: To investigate the clinicopathologic features and immunophenotype of invasive-stratified mucin-producing carcinoma (ISMC). Methods: We retrospectively analyzed three patients who underwent surgery for pathologically confirmed ISMC from January 2017 to December 2017 in Anyang Tumor Hospital. The pathological features, immunophenotype, and prognosis were discussed. Results: Clinical symptoms and imaging were atypical. Microscopically, the arrangement of tumor cells is close to that of squamous cell carcinoma, showing flake or nested growth. Morphologically, tumor cells were reminiscent of adenocarcinoma. The tumor cells showed abundant intracytoplasmic mucus which routinely created spacing between adjacent nuclei. The nuclei was round or oval with irregular karyotypes, thick nuclear membrane, staining empty light, rough chromatin, visible small nucleoli. Mucous vacuoles or pink-stained foam were visible in the cytoplasm. Mitotic features and apoptotic bodies were seen in the invasive component of all three cases, whereas all but one of these showed a neutrophil-dominant inflammatory cells infiltration. A large number of histocytes were found in the stroma of two cases. Special staining of mucus confirmed the presence of mucus in cytoplasm. Immunohistochemical results showed that tumor cells were strongly and diffusely positive for p16 and CK7 and had high Ki-67 expression. Conclusions: ISMC is a rare tumor in female genital tract and is often misdiagnosed as squamous cell carcinoma and other cervical cancers. The diagnosis mainly depends on the unique clinicopathologic features together with the immunophenotype. Treatment and prognosis, like other cervical cancer, are mainly based on clinical stages.