A new vision of tubular and tubulo-lobular carcinomas of the breast, as revealed by 3-D modelling

AIMS: To reveal architectural structure and growth patterns of tubular carcinomas (TC) and tubulo-lobular carcinomas (TLC) of the breast. METHODS AND RESULTS: We studied a series of 20 pure TC and 22 TLC, evaluating the architectural features of the two entities by bi-dimensional microscopy and by 3-D modelling. We traced the spatial organization of three TCs and three TLCs on serial sections using AE1/AE3 cytokeratin as a marker of the epithelial structures and reconstructed 3-D models of each histological type. The analysis of TC on serial cytokeratin-stained sections showed that the form of the 'tubules' was related to the plane of sectioning and that often they were tear-drop shaped, with a final tail of single cells connecting them together. 3-D models corresponded to a necklace appearance and the tubules of TC appeared as blebs bridging through solid cords to other blebs. In TLC the structure was similar, but the connecting single-cell files were usually longer. Both TC and TLC showed similar E-cadherin positivity and an indolent clinical behaviour. CONCLUSIONS: TC and TLC share the same architectural and growth patterns and ultimately seem to represent variants of the same tumour type.