ERBB2 and neoplasm: The tumor was ER/PR-positive, HER2-negative, with a low Ki-67 index (3%), and was completely excised with negative margins.<h4>Discussion</h4>Pure MCB exhibits favorable biological behavior and excellent outcomes, particularly when accurately diagnosed through histopathological and immunohistochemical evaluation.<h4>Conclusion</h4>Pure MCB is a rare, low-grade tumor with distinct pathological features.