Mesothelial neoplasms presenting as, and mimicking, ovarian cancer

Abstract

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.

FIG. 1.

Multicystic mesothelioma was comprised of multiple variably sized cysts separated by fibrous/adipose septa; cysts were lined by a single layer of flattened-to-cuboidal/hobnailed mesothelial cells with no or little atypia [(A) hematoxylin and eosin, 200 ×]. Lining cells were uniformly positive for calretinin [(B) 200 ×] and cytokeratin5/6 [(C) 200 ×].

FIG. 2.

The tumor in case number 1 showed cells in papillary and tubular formations (hematoxylin and eosin, 100 ×), that were positive for calretinin and cytokeratin5/6 (not shown).

FIG. 3.

Case number 2 showed features of a borderline mucinous tumor [(A) H&E, 100 ×]. A mural nodule was identified, comprised of a malignant sarcomatoid [(B) H&E, 100 ×] and epithelioid neoplasm [(C) H&E, 200 ×], positive for calretinin [(D) 200 ×]. H&E indicates hematoxylin and eosin.