Approach to the growing breast lump during lactation

Abstract

Physiological changes during pregnancy and lactation result in increased lumpiness of the breast. This makes the evaluation of the breast challenging. Although most self-detected lumps, during this period, tend to be benign, the priority in these patients is to exclude tumours that may require prompt management. We present a case of phyllodes tumour that occurred during lactation and discussed the resultant pitfalls that may occur during the triple assessment of a breast lump in a lactating mother.

Background

Physiological changes in the breast during pregnancy make self-breast examination challenging. Most lumps detected during pregnancy are benign (80%),^{1 2} with galactocele being one of the more commonly detected breast lumps during pregnancy (22.5%).²

We present a case of a young lactating mother whose breast lump was deemed likely a fibroadenoma which had undergone a lactational change but eventually proved to be a benign phyllodes tumour on final diagnostic excision.

Case presentation

A lactating mother in her 30s presented to our clinic with an enlarging left breast lump of 1-year duration. This lump was first noted by the patient 3 months prior to her pregnancy and had been stable in size until she started breast feeding.

On examination, there were no nipple retraction or visible skin changes on both breasts. A palpable non-tender lump measuring 8 cm was felt in the inner lower quadrant of the left breast. No palpable lump was felt in the right breast. There were no palpable axillary or supraclavicular lymph nodes.

Investigations

Bilateral breast ultrasound showed a large heterogenous mass with internal cystic spaces measuring 8.1 cm in the left breast (figure 1) and a prominent lymph node measuring 2.0 cm with borderline cortical thickening in the left axilla (figure 2). Findings over the right breast were unremarkable.

Figure 1.

Ultrasound imaging of the left breast heterogenous mass containing cystic spaces.

Figure 2.

Ultrasound imaging showing an enlarged lymph node with borderline cortical thickening in the left axilla.

Three millimetres of milky contents was aspirated from the left breast lump, and the contents were sent for cytology. The residual lump was 6 cm in size. A core biopsy was performed for it, which showed a tiny portion of fibroepithelial lesion, foci of lactational changes and dilated ducts. Core needle biopsy of the prominent lymph node returned as reactive changes. The combined findings of cytology which yielded milky contents along with the biopsy showing portions of a fibroepithelial lesion (figures 3 and 4) were consistent with a fibroadenoma with lactational change. These findings were discussed in a multidisciplinary tumour board and were deemed to be concordant. The likely explanation for the large size was thought to be related to pregnancy or lactation in which fibroepithelial lesions can increase in size due to changes in the hormone milieu, in the body. As the lesion was deemed likely to be of benign origin, the decision was made to monitor the lesion until cessation of breast feeding. We were concerned with the risk of milk fistula formation should an excision be performed.³

Figure 3.

Core biopsy (H&E stain 20×) showing lactating breast tissue (green arrow) with dilated ducts and a few cystic spaces (black arrow) in keeping with a fibroadenoma.

Figure 4.

Papanicolaou-stained cytospin preparation showing background proteinaceous material with a few apocrine-type ductal cells and macrophages consistent with origin in a galactocele.

Monitoring of the breast lump was performed with 6-monthly interval ultrasounds. During the patient’s first follow-up visit, the lump had reduced to 4.4 cm on cessation of breast feeding. However, at her 1-year follow-up, the patient reported a sudden increase in size of the left breast lump. On clinical examination, the lump replaced the breast with stretching of overlying skin without ulceration. There were no palpable axilla lymph nodes (figure 5). A repeat core biopsy of the breast lump showed a fibroepithelial lesion with increased cellularity. The presence of periductal stromal accentuation, mild stromal atypia, a mild to moderate increase in stromal cellularity and one to two mitoses per high-power field were observed. These findings are consistent with a phyllodes tumour (figure 6).

Figure 5.

Clinical photograph of the patient’s left breast mass occupying the entire breast on clinical examination.

Figure 6.

Core biopsy (H&E stain 40×) showing a cellular fibroepithelial lesion with an expanded stroma. No background lactational change was observed.

Treatment

The patient underwent a left nipple-sparing mastectomy (figure 7) with axillary sampling followed by an immediate reconstruction of the breast with an extended latissimus dorsi flap. Final histology was a completely excised benign phyllodes tumour (figures 8 and 9).

Figure 7.

Clinical photograph of the patient’s left breast mass after excision.

Figure 8.

Excision specimen showing a benign phyllodes tumour with a well-circumscribed border (Black arrow) (H&E stain 40×).

Figure 9.

Excision specimen showing a benign phyllodes tumour with cleft-like ducts and no stromal overgrowth (H&E stain 20×).

Outcome and follow-up

The patient’s postoperative recovery was uneventful, and she was discharged 2 days later. For the past 8 months, she had been doing well, and no symptoms or signs of recurrence had been noted. The patient is also satisfied with the aesthetic result of the reconstructed breast, which shows good symmetry between both sides. She is scheduled for a yearly review in our clinic.

Discussion

Physiological changes during pregnancy and breast feeding make breast examination challenging. Most palpable breast lumps (80%) reported by pregnant and lactating patients are physiological and turn out to be benign when biopsied.^{1 2} The priority in these patients is to exclude cancerous lumps.

Higher oestrogen and progesterone production by the body during the first two trimester results in lobular and ductal proliferation of the breast, respectively. In the third trimester, as the body prepares for lactogenesis, increased secretion of prolactin slows the proliferation process. This results in hyperplastic changes in the breast which do not occur evenly and are often perceived as breast lumps.¹ Proper evaluation of a pregnant/lactating breast is thus crucial to ensure timely diagnosis of lumps that may require prompt management. However, evaluation of a lactating breast is challenging, both clinically and radiologically,^{1 4} due to the structural changes described earlier. Masses could also be obscured during radiographic evaluation, leading to a delay in diagnosis.⁵

Phyllodes tumour is a rare neoplasm of the breast that presents as a painless enlarging lump in the breast, with the most common location being the outer upper quadrant.^6–8 It tends to occur in younger females, in their 30s,⁹ as compared with breast cancer that more commonly involves women in their 40s.¹⁰ Accurate characterisation of a phyllodes tumour can only be diagnosed on final excision. However, there are some preoperative findings that can suggest its diagnosis after a triple assessment has been completed.⁷

Radiological evaluation of a lactating breast is often employed to confirm the presence of a lesion and to characterise it.⁴ On ultrasonography, a phyllodes tumour would appear as a smooth and well-circumscribed nodule that is lobulated with an echogenic rim. The presence of fluid-filled clefts in a predominantly solid mass is a key finding.⁹ When these features are observed, the lesion is considered radiologically suspicious, and a core needle biopsy will be recommended for further evaluation. MRI of the breast is not recommended for characterisation of any lumps in pregnancy or during lactation. Physiological changes, such as an increase in breast vascularity, limit the sensitivity of MRI.¹¹ Gadolinium exposure, which is required in breast MRI,¹ has also been associated with an increased risk of developing adverse skin conditions in the newborn, stillbirths as well as neonatal deaths.¹² Furthermore, the findings from breast MRI cannot be used to confidently differentiate between phyllodes tumour and fibroadenoma.¹³

Core needle biopsies are hence considered the most reliable method for diagnosis to distinguish between benign and malignant lumps,¹ and it is a generally safe procedure, even in lactating breasts.⁵ Patients should be counselled on its main complication which is a milk fistula formation.^{3 14} Histologically, a benign phyllodes tumour shares common features with fibroadenoma, as both lesions are fibroepithelial lesions. In the absence of key histological features, this could be a diagnostic challenge and the most likely diagnosis should only be made after considering its clinical and imaging findings.¹⁵ Having a proper preoperative diagnosis is essential for surgical planning.⁷

Even with the aid of histological assessment, the diagnosis of a lump in a lactating breast remains complex. The initial impression of this lump was a fibroepithelial lesion that had undergone lactational change because the pre-existing phyllodes tumour had superimposed lactational changes that clinically masqueraded as a galactocele. The biopsy most likely only sampled the banal portion of the phyllodes tumour, which is known to be heterogeneous in architecture. As the preoperative histology leaned towards a fibroadenoma, we elected to monitor the lump due to its large size. Since it is not possible to conclusively diagnose a phyllodes tumour without surgical excision, close follow-up in a lactating patient until resolution of the lump is recommended.¹⁶ Based on the authors’ experience, lactational changes tend to resolve within 6 months after cessation of breast feeding. Hence, we suggest considering a histological reassessment for non-resolving lumps only after 6 months or if there are any suspicious changes during follow-up.

Learning points.

• Most breast lumps detected during lactation are benign, but prompt evaluation should be carried out to ensure malignancy is excluded.

• Clinical and radiological examination during lactation is challenging due to normal physiological changes. Core needle biopsy is considered the gold standard in ruling out a malignant lump.

• Breast lumps detected during pregnancy should be followed up until the patient has ceased breast feeding.

• A core needle biopsy should be reconsidered for suspicious lumps even if the initial histological assessment, during pregnancy/lactation, was benign.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).