Role of CD10 Immunoexpression in Grading Phyllodes Tumour of the Breast

Fibroepithelial tumours are a heterogeneous group of biphasic neoplasms consisting of a proliferation of both epithelial and stromal components. Fibroadenoma (FA) and Phyllodes Tumour (PT) constitute the major entities. It is crucial to distinguish benign from borderline PT (low grade malignant PT), because the former do not metastasize, have a lesser risk of local recurrence and initial local recurrences are histologically benign in almost all instances. Multiple Immunohistochemical (IHC) markers are being studied to find their utility in grading the PT accurately for planning proper treatment.

To study, the IHC expression of CD10 in the stromal cells of a series of PTs and FA, with the aim of determining whether the degree of CD10 expression in the stromal cells is related to the grade of the tumour.

Records of 28 cases of PT and 35 cases of FA received in the Department of Pathology in a tertiary care hospital were obtained. Histopathology reports and slides of all the cases were reviewed and clinical data such as age and histomorphological features such as tumour cellularity, stromal overgrowth, mitotic count and nuclear atypia were noted. Representative block of the tumour with maximum cellularity was subjected to CD10 staining. For FA and benign PT a technique of tissue microarray was used. For borderline and malignant PT, representative section was used. Stromal cell staining was assessed, using cytoplasmic staining of the breast myoepithelium as internal control.

Present study included 35 cases of FA, 20 cases of benign PT, five cases of borderline PT and three cases of malignant PT. The mean age of the patients increased with the increasing tumour grade of PT and this was also observed for FA and benign PT. The mean age increased with increase in tumour grade of PT and was statistically significant (p<0.05). The mean size did not increase with the increasing tumour grade of PT and was statistically insignificant (p=0.0429). Mean tumour size was more in benign PT as compared to FA and was highly statistically significant (p<0.01). CD10 staining was diffuse (Grade-3) and strong in malignant PT. The staining intensity was strong but patchy (Grade-2) in borderline PT. Weak and patchy (Grade-1) CD10 staining was seen in four benign PT and six FA. Other cases of benign PT and FA were negative for CD10 immunoreactivity.

Our study showed that CD10 expression strongly correlates with the PT grade, which can help in the differentiation between benign and malignant variants of PT.