MUC5AC and breast carcinoma: The LOB pattern was characterized by tumor cell growth within the ductal walls, like pagetoid spread of lobular carcinoma in situ (LCIS) (Figure 2F,G, supplementary material, Figure S3) 12, 13, associated with intracellular clear, mucin‐like vacuoles bestowing a signet‐ring cell‐like appearance on the tumor cells (Figure 2F).