Go back to the list of case studies
                                                                                                                         Click on the pictures to magnify and display the legends

Case number:	147
Age:	44
Clinical presentation:	Premenopausal woman with average risk of developing breast cancer presented with a left axillary lump. The lump has been present for many years but appears to have increased in size recently and the patient is concerned about how it looks. Examination reveals a soft tissue bulge in the left axilla, but no palpable breast lesion.

Mammography:

Breast composition:	ACR category c (the breasts are heterogeneously dense, which may obscure small masses)
Mammography features:
‣ Location of the lesion:	Accessory breast tissue with fibroglandular tissue is seen in the left axilla. No abnormalities seen in bilateral breasts
‣ Mass:
• Number:	0
• Size:	None
• Shape:	None
• Margins:	None
• Density:	None
‣ Calcifications:
• Typically benign:	None
• Suspicious:	None
• Distribution:	None
‣ Architectural distortion:	None
‣ Asymmetry:	None
‣ Intramammary node:	None
‣ Skin lesion:	None
‣ Solitary dilated duct:	None
‣ Associated features:	None

BI-RADS:

BI-RADS Category: 2 (benign)

Case summary:

Premenopausal woman presented with a left axillary lump. Diagnosed as left axilla accessory breast tissue, BI-RADS 2 on imaging.

Learning points:

Accessory breast tissue is a normal variant and can present as a mass anywhere along the course of the embryonic mammary streak (axilla to the inguinal region), but is commonly seen as an axillary accessory breast in addition to the normal breast tissue. It can be unilateral or bilateral. Accessory breast tissue is present since birth, but the woman is unaware of it until puberty, pregnancy, or lactation when it undergoes changes under hormonal influence. Accessory breast is known to undergo all the physiological changes and is also the site for development of benign breast masses, commonly fibroadenoma, cyst, fat necrosis, and neoplastic mass of breast cancer.