Clinicopathological and immunohistochemical analysis of sclerosing stromal tumours of the ovary

Sclerosing stromal tumours (SST) of the ovary are rare, benign tumours. SSTs are usually hormone inactive and tend to occur in the second and third decades of life. The most common clinical symptom is menstrual irregularity.

Fourteen women diagnosed with SST of the ovary were included in this study. Tumour samples were collected, embedded in paraffin and stained with haematoxylin and eosin, periodic acid-Schiff (PAS), and PAS with digestion, as well as immunohistochemically for vimentin, smooth muscle actin, desmin, CD 99, inhibin-α and the oestrogen and progesterone receptor.

The age of the patients ranged from 16 to 54 years (mean age 25.2 years). The tumours ranged in size from 6 to 21 cm (mean 10.5 cm). Macroscopically, eight tumours were solid and six were solid and cystic. All SSTs were well circumscribed with pseudolobule formation. Spindle-shaped fibroblast-like cells and vacuolated theca-like cells were prominent. Blood vessels exhibited a hemangiopericytomatous pattern and boomerang-like features. Immunohistochemical results were as follows: vimentin, 14/14 cases positive; smooth muscle actin, 14/14 cases positive; desmin, 14/14 cases positive; CD 99, 4/14 cases positive; inhibin-α, 14/14 cases positive; oestrogen receptor, 0/14 cases positive; progesterone receptor, 2/14 cases positive.

The characteristic histopathological features we observed in our study are usually adequate for the diagnosis of SSTs. Although inhibin-α, CD 99 and desmin staining may be a useful and reliable tool for SST diagnosis in problematic cases, an immunohistochemical panel will not discriminate from other tumours in the sex cord-stromal group.