ACTA1 and invasive lobular breast carcinoma: The most common subtype of invasive breast carcinoma, invasive carcinoma of no special type (IBC-NST), is known for its stromal loss of CD34+ fibroblasts while acquiring alpha smooth muscle actin-positive (α-SMA+) myofibroblasts, i.e., cancer-associated fibroblasts (CAF), whereas invasive lobular carcinoma (ILC) displays partial preservation of CD34+ fibroblasts.