Painful pressure in the left axilla of the breast can be the result of an occupying lesion in the axilla, most commonly the axillary parametrium, also known as parametrium or polymastia, which is the result of a legacy of embryonic breast tissue that has not completely degenerated, and which can also manifest as a localized raised mass, and in some cases, regular pain. The occurrence and development of parastomastia is also associated with changes in hormone levels in the body, especially after pregnancy or childbirth, which can lead to an increase in the size of the parastomastia. If necessary, surgical excision is required, as well as pathological examination and regular local color ultrasound. In some patients, enlargement of the axillary lymph nodes may also present as localized pain and a distinctly painful lump.