Ovarian serous carcinoma associated with a distinct "corded and hyalinized" pattern

The "corded and hyalinized" pattern, described in endometrioid carcinoma, has not been previously reported in association with serous carcinoma. We describe a unique case of serous neoplasm of low malignant potential with low-grade serous carcinoma combined with a distinct pattern of high-grade carcinoma characterized by cords of epithelioid and spindled cells enmeshed in a hyalinized, collagenous stroma. This pattern was the predominant architecture in the patient's recurrence and caused a diagnostic challenge, as the splenic recurrence was initially diagnosed as a second primary high-grade spindle cell neoplasm. Both ovarian and splenic tumors displayed positive immunohistochemical staining for cytokeratin 7, cytokeratin 8/18, estrogen receptor, and paired box gene 8 (PAX-8) in the conventional serous carcinoma and the corded and hyalinized component, confirming the diagnosis of recurrent carcinoma. The behavior in this unique case of serous carcinoma associated with a distinct corded and hyalinized pattern was more aggressive than low-grade serous carcinoma, but more favorable than malignant mixed mullerian tumor.