Unusual Case of Large Infarcted Lactating Adenoma

Richard H. Fryer, MD, James M. McGreevy, MD, and W. Bradford Rockwell, MD, University of Utah Health Sciences Center, Salt Lake City

Published Online: November 20, 2007 - 10:38:05 AM (CST)

Lactating adenoma is the most prevalent breast mass diagnosed in pregnant and lactating women. Changes in the breast parenchyma associated with pregnancy complicate the diagnosis and make decisions regarding surgical intervention more difficult. It is imperative that this benign condition is differentiated from breast cancer. Because approximately 3% of all breast cancers occur in women who are pregnant, a breast mass in this group of women must be investigated.¹ Fine-needle aspiration with cytologic evaluation is the most helpful diagnostic tool, although the presence of atypical cells can lead to false-positive reports. Mammography and ultrasound are often difficult to interpret.

We report an unusual case of lactating adenoma, presenting as asymmetrical enlargement of the right breast instead of the typically distinct, spongy breast mass.

Case Presentation

A 21-year-old primiparous woman presented with an asymmetrical enlargement of the right breast. Her initial obstetric evaluation took place at 27 weeks' gestation, at which time her right breast had enlarged to twice the size of the left. The right breast had striae; the left did not. On examination, no discernible mass was found in the right breast, and no nipple discharge was evident. The right breast was described as regular, firm, indurated tissue with no dominant coalescent mass.

The presentation suggested an abnormality of the left breast, indicating it was not responsive to the gestational state, whereas the right breast was enlarging as expected. An ultrasound of the right breast, performed by a radiologist, did not show a mass but rather a diffuse edematous pattern of the breast parenchyma, with scattered dilated ducts. A random fine-needle aspiration of the right breast produced cytologic material that was interpreted by the cytopathologist as showing reactive ductal epithelium suggestive of a lactating adenoma. When the patient returned 1 month later, the physical examination findings had not changed. She was instructed to return after her delivery, which was scheduled for the following month.

The patient delivered a normal child but did not return as directed. Instead, she appeared for follow-up 3 months after her last evaluation. She was breast-feeding from both breasts, although the baby preferred the left side. At this time, the breast examination findings were remarkably changed. The abnormality in the right breast had localized entirely to the lower pole, where the borders of the soft mass could be delineated (Figure 1). She was instructed to stop breast-feeding in preparation for excision of this giant mass. Because of the large size, a plastic surgery consultation was obtained in anticipation of reconstruction after excision.

Figure 1—Preoperative view of the enlarged right breast compared with the left breast, which is involuted 2 months' postpartum. The mass in the inferior pole of the right breast is stretching the overlying skin and the nipple?areolar complex.

Within 1 week of stopping breast-feeding, the patient complained of increasing pain in the right breast. She developed an obvious breast abscess, which was incised and drained. After several days of wound care, operative treatment of the breast mass was undertaken.

Operative findings
The right breast mass was in the inferior portion of the right breast and became more distinct as postpartum breast involution progressed. The distance from the nipple to the inframammary crease on the involved right side was 15 cm; the comparable distance on the uninvolved breast was 7 cm (Figure 2).

Figure 2—The necrotic core of the lactating adenoma has progressed to the lateral side of the breast, with necrosis of the overlying skin. The nipple-to-inframammary crease distance is 15 cm on the right breast, and 7 cm on the left breast.

An elliptical excision of skin was performed in the inferior portion of the right breast, preserving the nipple-areolar complex. A mass surrounded by a capsule was identified. Dissection proceeded around the entire capsule, allowing removal of the mass. Several larger perforating blood vessels from the pectoralis major muscle entered into the deep surface of the mass, which did not invade the overlying skin or the underlying muscle. The glandular and ductal tissue of the preserved breast tissue remained connected to the nipple. Manipulation of the remaining breast tissue occasionally caused milk to emanate from the nipple. The postoperative appearance of the breast revealed redundant skin inferiorly, but the volume of the right breast matched the left breast fairly well (Figure 3). No immediate reconstruction was undertaken because of the reasonable symmetry.

Figure 3—Postoperative view showing persistent redundant skin on the inferior portion of the right breast. The diameter of the areola decreased significantly after removal of the mass.

Pathologic findings
The specimen weighed 490 g and measured 14.0 x 10.0 x 7.0 cm. (The usual size of a distinct mass is no more than 4 cm in diameter.) A capsule covered the majority of the specimen. The central aspect was composed of necrotic material, which varied from mildly fibrous to mucoid (Figure 4).

Figure 4—The pathologic specimen measured 14 cm in greatest diameter, with a capsule surrounding the majority of the mass. The necrotic central portion progressed to the skin overlying the lateral portion of the mass (see Figure 2).

The microscopic sections showed benign breast tissue, with a proliferation of lobules and lactational changes characterized by vacuolated secretory cells. The ducts were unremarkable, except for minimal chronic inflammation and mild fibrosis. No evidence of neoplastic change was seen, and the overlying skin was unremarkable. The findings were consistent with a lactating adenoma.

Discussion

Lactating adenoma is the most common breast mass diagnosed in pregnant and lactating women. Nevertheless, they rarely occur. Because up to 3.9% of all invasive breast cancers arise during pregnancy, breast masses discovered during gestation and puerperium must be carefully scrutinized.¹ From a different perspective, 1 in 3000 pregnancies may be associated with breast cancer.²

Unlike breast cancer, the prognosis for lactating adenomas is uniformly favorable, because these benign lesions have no potential for malignant transformation. Most lactating adenomas are first noticed during pregnancy and may continue to grow with lactation. Hormonal influences during pregnancy and lactation produce ductal proliferation, more secretory mammary alveoli, and a volumetric expansion of the alveoli.³ Most lactating adenomas are 1 to 4 cm in the greatest diameter. Despite their occasional very rapid growth, they are always benign.

Clinically, a dominant mass is usually readily identifiable. Mammogram and ultrasound are often difficult to interpret because of gestational and lactational breast changes.^2,4 Fine-needle aspiration can provide helpful diagnostic evidence.⁵ Cytologic features include scattered epithelial cells, sometimes coalescing in small groups. Vacuolated or foamy cytoplasm is noted within the acinar cells. Slightly atypical cells are sometimes found in cytologic aspirates and can lead to false-positive results. On cross-section, the cut surface is tannish yellow and multilobulated.⁶ Other normal lactational changes dominate the microscopic architecture.

The average age at presentation is 25 years. The lesions typically present as nontender, freely mobile, enlarging masses. The majority are found within the breast, but lactating adenomas within accessory breast tissue in the axilla and vulva have been reported.^7,8 Synchronous lactating adenomas may exist in different areas of the same or contralateral breast. Lactating adenomas are usually self-limited and generally involute with the cessation of lactation.⁹ They do not tend to recur locally after spontaneous involution or surgical excision. At 2 years of follow-up, our patient had not had any recurrence of the adenoma.

Larger, more rapidly progressive lactating adenomas have been mistaken for inflammatory breast cancer or breast abscess.⁸ Overlying skin changes, breast pain, and sometimes febrile episodes contribute to the misdiagnosis. Plastic reconstructive surgery after resection of large adenomas may be necessary. Our patient has not requested further reconstruction of her breast, because the skin had contracted to accommodate the smaller breast volume. Although the contour of her lower breast is not perfect, and a moderate asymmetry compared with the left breast is evident, she is satisfied with the result.

When indicated, reconstruction would typically be performed with an implant; autologous tissue reconstruction would rarely be required. Bromocriptine mesylate (Parlodel) may help larger tumors regress, simplifying the resection and decreasing the need for more aggressive reconstruction. Because bromocriptine causes cessation of lactation and eliminates the option of breast-feeding, it should be instituted only after informing the patient of this effect.

A multidisciplinary approach to the management of lactating adenomas—involving primary care physicians, obstetricians, radiologists, pathologists, general surgeons, and plastic surgeons—can help in the diagnosis and treatment of this condition, with its frequently confusing or atypical presentations. After the diagnosis has been confirmed, the patient can play an active role in deciding between conservative or more aggressive treatment options.

Conclusion

This case of a large lactating adenoma highlights the diagnostic and therapeutic dilemmas associated with this condition. The therapy for lactating adenomas is mostly conservative, in contrast to the obvious need for surgical excision in the case of breast cancer. Interdisciplinary coordination is necessary when evaluating and treating patients with lactating adenomas, especially when size or symptomatology dictate surgical intervention.

References

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