Dedifferentiated Endometrioid Carcinomas with Neuroendocrine Differentiation: A Clinicopathological and Immunohistochemical Study of Three Cases

PURPOSE: To investigate the relationship between dedifferentiated endometrioid carcinomas with neuroendocrine differentiation and mismatch repair deficiency. PATIENTS AND METHODS: The clinicopathological records and samples of three patients were retrieved from the Pathology Department of Zhejiang University’s School of Medicine Women’s Hospital. RESULTS: The tumors comprised one dominant poorly differentiated component (60–90% of the neoplasm volume) and one well-differentiated glandular component. The poorly differentiated component showed solid sheets with organoid growth patterns and insular, trabecular and rosette/pseudorosette patterns. Large polygonal cells, vesicular nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm were observed in the poorly differentiated area. All three cases were diffusely positive for p16 and for at least two of three neuroendocrine markers (chromogranin, synaptophysin, neural cell adhesion molecule (CD56)) in >10% of cancer cells. Loss of MMR protein expression was found in two patients: MLH1 and PSM2 in patient 2 and MSH2 and MSH 6 in patient 3. Abnormal P53 and SMARCB1 (INI1) expression was noted in patient 3. All three patients underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy, and two received postoperative chemotherapy and/or radiation therapy. The patients survived disease-free for 60, 26 and 15 months, respectively. CONCLUSION: Dedifferentiated endometrioid carcinomas with neuroendocrine differentiation may be associated with mismatch repair deficiency and have an improved prognosis.