Akashi M, Yamaguchi R, Kusano H, et al. - In this study, the clinicohistomorphological features of each HER2-positive (HER2+) breast carcinoma (BC) subgroup were evaluated. A total of 166 individuals with HER2+ invasive BC were divided into LH (n = 110, 66.3%) and NLH groups (n = 56, 33.7%). For clinicohistomorphological characterization, researchers further subdivided LH into patients with carcinomas expressing high levels of hormone receptors [LH-high; Allred score, estrogen receptor (ER) and/or progesterone receptor (PgR) 4–8, n = 89, 53.6%] or low levels (LH-low; Allred score, ER and/or PgR 2 or 3, n = 21, 12.7%). These outcomes help the group of HER2+ BC into two major subgroups, LH-high and NLH, based on tumour morphology and immune response; LH-high proliferates via scirrhous and/or spiculated growth with a central scar, while the primary proliferation pattern of NLH is based on in-situ carcinomas containing comedo necrosis with remarkable TILs and healing.