An extra piece of flesh under the armpit should be promptly examined by color ultrasound of the breast and the armpit. This is because the most common form of parametrium, which occurs in the armpit, is a benign condition that is associated with congenital abnormalities. It is caused by the degeneration of the breast tissue during the embryonic period and can be painful. If there is no clinical discomfort, the patient can be reviewed regularly and temporarily observed. If the pain is significant, surgical excision is an option, which can be performed under local anesthesia and does not require hospitalization. The lesion is carefully separated and excised, and postoperative pathological examination and regular dressing changes and stitch removal are required.