Although tumor size and grade are well-established prognostic parameters in unselected series or in advanced cases of invasive breast carcinoma, studying their prognostic value in small invasive carcinomas has generated variable results. The significance of these parameters was recently questioned in three large studies on invasive carcinomas less than 15 mm in size, in which neither grade nor size were found to be independent prognostic parameters. Two of these studies were carried out on material of our institution and evidenced the outstanding prognostic significance of a radiological parameter (presence of casting type microcalcifications) in these tumors, challenging the traditional approach in breast pathology in which conventional morphologic prognostic parameters are clearly insufficient to explain these results. In the present article we discuss the practical difficulties in measuring and grading invasive breast carcinomas to point out the disturbing lack of wide international consensus considering the optimal assessment of these parameters, contributing to discordant results in the reviewed studies. We also present the unifying concept of the theory of the sick lobe which, by shifting the focus from the debated details of measuring and grading towards the judgement of the pattern of tumoral growth, offers alternative morphologic prognostic parameters which fulfill the needs of a modern interdisciplinary approach to diagnosing small breast carcinomas.

Keywords: Breast Neoplasms - pathology, Carcinoma, Lobular - pathology