Diagnostic stromal histomorphology in fibroepithelial breast lesions: a fresh perspective

Histopathologic parameters were studied in fibroepithelial breast lesions comprising of Fibroadenomas (FAs), Juvenile cellular fibroadenomas (JCFs) as well as benign, borderline and malignant phyllodes tumours (B/Bo/MPTs). H & E stained sections of 67 cases (25 ICFA, 5 Mixed FA, 10 PCFA, 12 JCF and 15 PT) were retrieved from archival material and the microscopic features of each lesion, reviewed by two independent observers. A diagnosis was arrived at by consensus. Diagnostic criteria were laid down for each of the above lesions based on a statistical analysis of data obtained from a previously drawn up semiquantitative grading system for various stromal histomorphologic parameters. An increasing grade of stromal cellularity, pleomorphism, overgrowth and mitotic index was observed, from the benign to the borderline and overtly malignant lesions included in the spectrum. A semiquantitative grading of relevant stromal histomorphologic variables was found to be of immense diagnostic significance in fibroepithelial breast lesions and served to elucidate cases falling into the diagnostic grey zones of the spectrum.