**3.1 Pathology of ovarian low-grade serous carcinomas**

Macroscopically LGSCs are often bilateral and have a papillary appearance. Foci of calcification may be present. Microscopically, they display papillary, micropapillary, glandular, nested or inverted macropapillary architectural patterns- free-floating within unlined empty spaces, with a variety of invasion patterns. Neoplastic cells demonstrate low to moderate grade nuclear atypia with no pleomorphism (<3× size variation), distinct central nucleoli and relatively low mitotic activity (1–2 mitoses/mm2 ). Necrosit areas are rare and psammoma bodies are frequent. LGSCs are differentiated from their serous borderline tumour component by the presence of stromal invasive foci measuring >5 mm or 10 mm2 in size [5, 69].
