During breastfeeding, a hard lump under the armpit is considered to be an enlarged lymph node in the armpit. Mastitis can easily occur during breastfeeding, especially in primiparous women, and is caused by milk stagnation. The symptoms can gradually improve. There are also some patients due to the occurrence of axillary parametrium, parametrium this disease belongs to congenital developmental abnormalities, especially after childbirth will lead to parametrium enlargement and changes in hormone levels in the body related, parametrium in the necessary case can choose surgery to remove.