Objective: To gain further understanding of the pathological features and biological behavior of solid papillary carcinoma (SPC) of the breast. STUDY DESIGN: We stained tissue sections of a right atrial tumor excised from a patient with SPC of the breast with metastasis to the right atrium, using hema-toxylin and eosin (H&E) staining and immunohistochemistry. Results: The solid area of the tumor showed an intermingled fibrovascular network with no apparent papillary structures on H&E staining, providing an auxiliary diagnosis for myocardial invasion. Immunohistochemical staining confirmed cardiac metastasis of invasive SPC of the breast. Conclusion: Pathological examination of this case improves our understanding of the diagnosis and treatment of metastatic SPC. © 2019 Science Printers and Publishers.