BackgroundBreast cancer brain metastasis (BCBM) is a growing therapeutic challenge and clinical concern. Stromal cancer-associated fibroblasts (CAFs) are crucial factors in the modulation of tumorigeneses and metastases. Herein, we investigated the relationship between the expression of stromal CAF markers in metastatic sites, platelet-derived growth factor receptor-beta (PDGFR-β), and alpha-smooth muscle actin (α-SMA) and the clinical and prognostic variables in BCBM patients.MethodsImmunohistochemistry (IHC) of the stromal expression of PDGFR-β and α-SMA was performed on 50 cases of surgically resected BCBM. The expression of the CAF markers was analyzed in the context of clinico-pathological characteristics.ResultsExpression of PDGFR-β and α-SMA was lower in the triple-negative (TN) subtype than in other molecular subtypes (p= 0.073 andp= 0.016, respectively). And their expressions were related to a specific pattern of CAF distribution (PDGFR-β,p= 0.009; α-SMA,p= 0.043) and BM solidity (p= 0.009 andp= 0.002, respectively). High PDGFR-β expression was significantly related to longer recurrence-free survival (RFS) (p= 0.011). TN molecular subtype and PDGFR-β expression were independent prognostic factors of recurrence-free survival (p= 0.029 andp= 0.030, respectively) and TN molecular subtype was an independent prognostic factor of overall survival (p< 0.001).ConclusionsExpression of PDGFR-β in the stroma of BM was associated with RFS in BCBM patients, and the clinical implication was uniquely linked to the low expression of PDGFR-β and α-SMA in the aggressive form of the TN subtype.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12885-023-10957-5.