Accessory breast tissue development frequently occurs in addition to physiologic breast development and is a common congenital condition with an occurrence of 0.4 % to 6% in women and 1 % - 3% in men. A 31-year-old G1P0 female presented to our triage at 20 + 4 weeks gestation with a one-week history of painful bilateral axillary lumps. Her last menstrual period was consistent with an estimated gestational age of 39 + 3 weeks by LMP. She had emigrated from Bengal three years earlier with no other gynecological complaints and knew of no abnormalities on physical exam. The painful axillary lumps were found to be accessory breast tissue. This entity is present ed as a palpable thickening that is most prevalent along the milk line in the region immediately below the breasts, along the abdomen, in the axilla and in the groin region adjacent to the vulva. Affected individuals may undergo premenstrual changes such as tenderness, swelling, and difficulty with shoulder range of motion and irritation. The onset of pregnancy stimulates the tissue and makes it more evident as it did with our patient.
The development of accessory breast tissue can be traced back to the developmental period during the 5th week of gestation when there is a thickening of the ectoderm known as the mammary ridge on the ventral surface of the developing embryo. The mammary ridge correlates closely with the milk line (60% to 70% of cases) and normally will regress to a single pair of breasts on the pectoral region as the embryo continues to develop over the ensuing months [
Our patient was designated as high risk due to diabetes and as such had scheduled weekly prenatal visits. She presented for prenatal care and bilateral accessory breast tissue nearby her axillae of 1 week duration. We communicated with the patient through a Cyracom interpreter. The patient endorsed changes coinciding with her menses consisting of fibrocystic changes in her breasts, as well as bilateral tender engorgements near her axillae. Prior to her visit, our patient was unaware of the possibility that these tender engorgements could be associated with accessory breast tissue. Bedside ultrasound was performed on the axillary engorgements to elucidate whether these masses were solid or cystic in nature. An echogenic area with an appearance paralleling that of typical breast tissue was visualized. Her history of cyclic premenstrual bilateral tender engorgements, physical examination (visual inspection and palpation) and sonographic findings allowed us to make a diagnosis of bilaterally axillary accessory breast tissue. On physical examination, there were no additional lesions visible or palpable along the milk line. She subsequently delivered a healthy baby and elected not to breast feed. The axillary breast tissue decreased in size over the ensuing month.
Accessory breast tissue development can take many forms and in the literature accessory breast tissue has been reported as polymastia, supernumerary breasts, and ectopic breasts. Accessory breast tissue was historically classified into eight subcategories which have since been simplified to the following: accessory breast tissue (otherwise known aspolymastia), polythelia, and aberrant breast tissue [
Accessory breast tissue frequently occurs in addition to physiologic breast development and is a relatively common congenital condition [
| Category | Nipple | Areola | Gland |
|---|---|---|---|
| Normal Breast or Complete Supernumerary Nipple | + | + | + |
| Polymastia | +/− | +/− | + |
| Polythelia | + | − | − |
| Aberrant Gland Tissue | − | − | + |
occur onother regions of the body aside from the milk line such as the buttocks, face, arm(s) and/or thigh(s); accessory breast tissue is not exclusive to the milk line, and when accessory breast tissue develops in non-milk line regions it is called ectopic breast [
Accessory breast tissue presents as a palpable thickening that is most prevalent along the milk line in the region immediately below the breasts, along the abdomen, in the axilla and along the groin region adjacent to the vulva [
Accessory breast tissue can be diagnosed through physical examination, and sonography can be used in conjunction as it is helpful in distinguishing whether accessory breast tissue is present in the region of interest. Both ultrasound and MRI could be used to confirm the presence of glandular tissue. Fine needle aspiration cytology is another tool that may be utilized if a mass is suspected [
Treatment for accessory breast tissue is most often supportive as the condition is often benign. Surgery is considered when there is malignancy or malignancy potential, difficulty with shoulder range of motion, engorgement during menstruation, or any cosmetic concerns [
Patients should be followed annually to be certain that no masses develop in the accessory breast tissue. If masses develop, a needle biopsy should be performed to rule out malignancy.
Accessory breast tissue is a relatively common congenital condition that can be diagnosed through physical examination in conjunction with ultrasound and/or MRI imaging technique. The accessory breast tissue is the same type found in a regular breast and is thus prone to the same physiological and pathological changes. The clinician should be prepared for an array of possible issues that may arise with accessory breast tissue, ranging from benign breast tissue and/or fibroadenomas to malignant breast cancers. A patient with accessory breast tissue in pregnancy and her fetus will have an excellent overall prognosis with supportive treatment.
The authors declare no conflicts of interest regarding the publication of this paper.
Paknejad, O., Bryant, D., Peterkin, C., Wilcox, W. and Follen, M. (2019) Accessory Breast Tissue in Pregnancy. Open Journal of Obstetrics and Gynecology, 9, 954-959. https://doi.org/10.4236/ojog.2019.97092