The actual fact is that there are several situations where there are grains and grains between the armpit and the breast: 1, breast hyperplasia, it may be that the breast hyperplasia is more powerful, resulting in a grain of hyperplastic nodules between the breast and the armpit. It is possible that the nodules between the armpits and the breasts may be caused by the hyperplasia of the breast. It is recommended to consult a local hospital for breast ultrasound or mammogram to determine whether it is breast cancer, if it is, surgery may be needed. 4. Lymph nodes, these small particles may also be caused by enlarged lymph nodes.