The term LCIS is used when the proliferative changes result in marked expansion of the lobular units by solid nests. In atypical lobular hyperplasia (ALH), the lobules are normal sized and still contain identifiable lumina. However, lobular enlargement is not an absolute diagnostic criterion for LCIS. Likewise, complete absence of lumens is not necessary for the diagnosis of LCIS. This image shows the spectrum of findings from ALH to LCIS.