Benign cystic mesothelioma of the peritoneum: A clinicopathologic study of 17 cases and immunohistochemical analysis of estrogen and progesterone receptor status

Benign cystic mesothelioma (BCM) is an uncommon lesion of the peritoneum occurring predominantly in women of reproductive age. Although most patients are managed by surgical resection, a reported high incidence of cyst recurrence has led to the use of hormonal therapy in isolated cases in an attempt to control cyst size and relieve local symptoms. To date, the estrogen receptor (ER) and progesterone receptor (PR) status of BCM has not been evaluated. Here we present our experience with 17 cases (13 women, 4 men) of BCM seen over a 19-year period, including an immunohistochemical analysis of ER and PR status in 14 cases. All lesions showed typical morphological features of BCM, and calretinin immunostaining was positive in 14 of 14 cases. Five patients experienced either 1 or 2 tumor recurrences, and no patients died of disease. One case was diffusely positive for ER only, 1 case was focally positive for PR only, and 1 case was focally positive for both ER and PR. Although immunohistochemical detection of female sex hormone receptors in BCM is uncommon, the focal presence of ER and/or PR in some lesions does provide weak biologic support for the use of hormonal manipulation as a therapeutic option.