Papillary serous carcinoma of the ovary: an ultrastructural and immunohistochemical study

Twenty-four patients with ovarian serous papillary carcinoma were enrolled in the present ultrastructural and immunohistochemical study. Immunohistochemistry was used to examine the status of proliferation activity with antibodies against Ki67 and BM28, and the status of EGFR family members with antibodies against EGFR, c-erbB-2, and c-erbB-4. Ultrastructurally, poorly differentiated tumors often revealed solid sheets of tumor cells with variable desmosomes, cell connection complexies, and microvilli. No mature cilia, which are often present in benign and borderline ovarian epithelial tumors, were seen in these 24 carcinomas. However, two poorly differentiated tumors demonstrated oligocilia. In addition, numerous secondary lysosomes and bizzare intracytoplasmic pseudocavities were more often present in the poorly differentiated tumors. Immunohistochemically, strong expressions of BM28 and Ki67 in more than 50% of the tumor cells were found in 12/15 (80%) and 11/15 (73%) of the poorly differentiated tumors, respectively, compared with 3/9 (33%) and 1/9 (11%) of the moderately differentiated tumors, respectively. Higher levels of EGFR and c-erbB-2 expressions were more often observed in the poorly differentiated tumors, compared with that in the moderately differentiated tumors. In conclusion, oligocilium, numerous secondary lysosomes, and bizarre intracytoplasmic inclusions are more often seen in poorly differentiated ovarian serous carcinomas. Poorly differentiated ovarian serous carcinomas express higher levels of Ki67, BM28, EGFR, and c-erbB-2 proteins.