Immunohistochemical staining for calretinin is useful in the diagnosis of ovarian sex cord-stromal tumours.

AIMS: Ovarian sex cord-stromal tumours are a heterogeneous group of neoplasms which may be confused morphologically with a wide variety of tumours. Calretinin positivity has previously been demonstrated in a small number of ovarian sex cord-stromal tumours. The aim of this study was to investigate calretinin staining in a series of these tumours and their histological mimics in order to determine the value of calretinin staining in a diagnostic setting.

METHODS AND RESULTS: Seventy-two neoplasms, including 37 ovarian sex cord-stromal tumours and 35 miscellaneous neoplasms which may enter into the differential diagnosis, were stained with a commercially available polyclonal antibody against calretinin. All sex cord-stromal tumours exhibited positivity except for a single fibrothecoma. In this group of tumours staining was generally diffuse and strong. Small numbers of the miscellaneous group of neoplasms exhibited positivity but this tended to be focal and weak, although this was not always the case. There was consistent strong positive staining of granulosa cells in follicular cysts and corpora lutea. There was also positive staining of luteinized stromal cells in two cases of ovarian stromal hyperplasia and hyperthecosis.

CONCLUSIONS: Calretinin is a sensitive immunohistochemical marker of ovarian sex cord-stromal tumours and may be useful in a diagnostic setting. However, the value is somewhat limited since occasional neoplasms which enter into the morphological differential diagnosis may be positive. Be that as it may, calretinin positivity may be of value in the diagnosis of an ovarian sex cord-stromal tumour and its differentiation from other neoplasms. In this regard, calretinin should always be used as part of a larger panel.