Distribution of alpha glutathione S-transferase in ovarian neoplasms: an immunohistochemical study

Aims: Alpha glutathione S-transferase (alpha -GST) has been shown to be an immunohistochemical marker for delta (4-5) isomerase, an enzyme active in steroidogenesis. The purpose of this study was to document the distribution of alpha -GST in ovarian neoplasms in order to evaluate its usefulness as a diagnostic tool. Methods and results: A total of 92 tumours (25 sex cord/stromal, 53 epithelial and 14 germ cell) were subjected to immunohistochemistry using a commercially available polyclonal antibody to of alpha -GST. The avidin-biotin complex was used as a detection system. Positive staining was found in luteinized stromal cells of all tumour types (58/92). This included the Leydig cells of Sertoli-Leydig cell tumours (7/7) and was particularly prominent in the stromal cells of both benign and malignant mucinous tumours (24/25). Granulosa and Sertoli cells showed weak or no intracytoplasmic staining, which is expected because they do not normally produce androstenedione. They did show some intranuclear staining. Malignant mucinous (12/25) and occasional other epithelial tumours showed focal intracytoplasmic positive staining. Yolk sac tumours showed focal positivity (7/8). Conclusions: Intracytoplasmic staining of stromal cells is considered to indicate steroidogenesis and intranuclear staining the intracytoplasmic transport function of alpha -GST. The intracytoplasmic staining of mucinous carcinomas might represent an up-regulation of some detoxification function. The findings suggest that antibody to alpha -GST has some value in the investigation of ovarian pathology and could readily be included in any panel of antibodies used to investigate ovarian neoplasms of uncertain histogenesis.