Mesothelial neoplasms presenting as, and mimicking, ovarian cancer.

Mesotheliomas of the abdominal cavity are rare tumors that primarily involve the peritoneum, mesentery, and omentum. The involvement of the viscera is usually secondary to bulky and extensive serosal disease. We describe 7 cases of mesothelioma in which the initial manifestation was that of an ovarian mass. All patients underwent surgery with a primary diagnosis of ovarian cancer. Clinical histories, gross features, and histology slides were reviewed. Immunostains were performed on all cases and electron microscopy was performed in 2 cases. The patients ranged in age from 22 to 52 years and the lesions ranged in size from 3.8 to 9 cm. Of the 7 cases, 4 were predominantly cystic and 3 were solid. Histologically, all cystic tumors were multicystic mesothelioma, whereas the 3 solid tumors were diffuse malignant mesotheliomas. One patient had a borderline mucinous tumor with the mesothelioma occurring as a mural nodule, an association not described earlier. The oldest patient in this series had a diffuse malignant mesothelioma of the peritoneum with predominant ovarian surface involvement. Mesothelial neoplasms can present as ovarian masses in young women. Awareness of this presentation is important to establish appropriate management.