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JBDJournal of Breast Disease

Invasive Ductal Carcinoma Arising from Ectopic Breast Tissue in Axilla: A Case ReportDong Sik Heo, Se Jeong OhDivision of Breast, Department of Surgery, Incheon St. Mary’s Hospital, The Catholic University of Korea College of Medicine, Incheon, Korea

Primary carcinoma of ectopic breast tissue is rare. We present a 57-year-old female patient with a large erythematous bulging mass in the right axilla. Imaging studies did not reveal any other lesions except for the one detected in the right axilla. Wide excision with axillary lymph node dissection was performed. The pathology report revealed a poorly differentiated carcinoma with no surrounding lymphoid tissue or lymphovascular infiltration or noncancerous breast tissue. We think that in our case the tumor was probably derived from a primary carcino-ma of ectopic breast tissue rather than from a metastatic tumor or occult breast cancer. One year later, the patient presented with a local re-currence at the ipsilateral breast. Mastectomy with chemotherapy was performed. After three cycles of chemotherapy, imaging studies re-vealed distant metastases. This case report and literature review describe the characteristics of ectopic breast cancer in the axilla and re-flects on which initial management strategy is appropriate.

Key Words: Axilla, Breast neoplasms, Human mammary gland

INTRODUCTION

Primary carcinoma of ectopic breast tissue has been reported only

in a small number of cases. Ectopic axillary breast tissue differs from

the axillary components of the tail of Spence, because it develops as a

result of the failed resolution of the mammary ridge, an ectodermal

thickening that extends from the axilla to the external genitalia [1].

Copeland and Geschickter [2] proposed a classification of ectopic

breast tissue, in which accessory nipple formation, areolar formation,

or both, with or without the glandular breast, is termed supernumer-

ary breast. In contrast, an aberrant breast refers to ectopic breast tissue

that lacks a nipple or the areolar complex. Thus, we refer to an aberrant

breast as ectopic breast tissue.

CASE REPORT

A 57-year-old female patient noticed an erythematous bulging le-

sion in her right axilla for 2 months. There was also a palpable mass in

her left breast that had been present for several years, but had not been

evaluated further. Physical examination showed a tender and poorly

defined mass measuring 5 cm in diameter with pustular discharge

from the central punctum in the right axilla, and a well-defined,

round mass in the left breast. There was no accessory nipple or areolar

complex in either axilla. The early diagnosis was infected epidermal

inclusion cyst or lymphadenitis. To confirm this diagnosis, we per-

formed a fine-needle aspiration (FNA) cytology test, which suggested

a probable metastatic carcinoma (Figure 1).

A mammography showed no lesions in the right breast and a well-

defined, hyperdense mass in the left breast. Ultrasonography revealed

a microlobulated, hypoechoic mass with irregular margins at the right

axilla, no mass in the right breast and a well-defined, hypoechoic mass

in the left breast. Contrast-enhanced magnetic resonance imaging

showed a right axillary mass measuring 8× 3.8 cm and conglomerat-

ed, enlarged lymph nodes with heterogeneous enhancement and an

enhancement kinetic curve resembling a washout pattern. However,

there were no abnormal findings in both breasts, except for a benign

mass in the left breast. Positron emission tomography-computed to-

mography (CT) and chest CT showed no other lesion except those

mentioned above (Figure 2). Routine hematological and biochemical

parameters as well as tumor markers (carcinoembryonic antigen, CA

15-3, CA 125) were within normal ranges. An ultrasound-guided core

CASE REPORTJ Breast Dis 2014 June; 2(1): 32-35http://dx.doi.org/10.14449/jbd.2014.2.32

Correspondence: Se Jeong OhDivision of Breast, Department of Surgery, Incheon St. Mary’s Hospital, The Catholic University of Korea College of Medicine, 56 Dongsu-ro, Bupyeong-gu, Incheon 403-720, KoreaTel: +82-32-280-5639, Fax: +82-32-280-5988, E-mail: ohsj@catholic.ac.krReceived: May 7, 2014 Accepted: June 15, 2014

http://dx.doi.org/10.14449/jbd.2014.2.32 http://www.jbd.or.kr

Ectopic Breast Cancer in Axilla 33

needle biopsy was performed. Pathological examination suggested a

poorly differentiated invasive carcinoma of unknown origin.

The surgical treatment of choice was a wide excision of the right ax-

illary mass with axillary lymph node dissection and an excisional bi-

opsy of the left breast mass. Pathological examination revealed a tumor

measuring 6× 4 × 3.5 cm abutting the metastatic lymph nodes. There

was no surrounding lymphoid tissue or lymphovascular infiltration in

the specimen, which was indicative of a primary carcinoma rather

than a metastatic carcinoma. There was an irregular subcutaneous

proliferation of fibrous connective tissue infiltrated by an invasive duc-

tal carcinoma (scirrhous carcinoma), with a high histological and nu-

clear grade (Figure 3). Since there were no regions of noncancerous

breast tissue and immunohistochemical analysis performed on paraf-

fin sections to detect the estrogen receptor (ER), progesterone receptor

(PR), and c-erbB-2 yielded negative results, additional immunostain-

ing procedures were performed to differentiate invasive ductal carci-

noma of the breast from other carcinomas including skin adnexal tu-

mors. The tumor cells were negative for the S100 protein and focally

positive for cytokeratin 5/6 and cytokeratin 19. The above histological

and immunohistochemical findings were suggestive of invasive ductal

carcinoma. A total of five out of 16 lymph nodes were positive for tu-

mor infiltration. There was no residual tumor on the cut margin. Path-

ological examination of the left breast mass revealed a fibroadenoma.

Postoperative treatment included chemotherapy (docetaxel, doxo-

rubicin and cyclophosphamide combination therapy, six cycles) and

radiotherapy. One year later, a regional recurrence was found on the

parasternal area of the right breast. A total mastectomy was per-

formed and the patient received chemotherapy treatment (paclitaxel

monotherapy, three cycles). The pathological reports revealed multi-

ple small-sized, recurrent masses on the inner portion of the right

breast. After chemotherapy, follow-up evaluation with a chest CT re-

vealed multiple suspicious metastatic lymphadenitises on the bilateral

internal mammary, left axilla and right mediastinum. After the che-

motherapy regimen was modified to gemcitabine and vinorelbine,

the patient has been in a tolerable state with a partial response.

DISCUSSION

The overall incidence of ectopic breast tissue is reported as 6% of the

Figure 1. A protruding mass on the right axilla.

Figure 2. Contrast-enhanced magnetic resonance image demonstrating a right axillary mass with heterogenous enhancement.

Figure 3. Pathology showing an irregular subcutaneous proliferation of fi-brous connective tissue infiltrated by invasive ductal carcinoma (scirrhous carcinoma) with no regions of noncancerous breast tissue (H&E stain, ×100).

http://www.jbd.or.kr http://dx.doi.org/10.14449/jbd.2014.2.32

34 Dong Sik Heo, et al.

general population [3]. Among this population, ectopic breast carci-

noma is rare and is reported as a disease that shows variations varies

in incidence rate. Chiari [4] reported that ectopic breast carcinoma ac-

counts for 0.3% of all breast cancers in one series, whereas it was 0.2%

to 0.6% in Japan. The ectopic breast tissue was predominantly located

in the axilla, with a frequency of 71% according to Evans and Guyton

[1] and 58% according to Marshall et al. [5]. The frequencies for other

sites were 18.5% in the parasternal region, 8.6% in the subclavicular re-

gion, 8.6% in the submammary region, and 4% in the vulvar region

[5]. Nihon-Yanagi et al. [6] reviewed 94 cases in Japan between 1978

and 2009 and reported that 91.5% of ectopic breast cancers occurred

in the axilla.

Pathological findings showed similar results to anatomic breast

cancers, which are mainly invasive ductal carcinomas [6,7]. FNA was

used as a diagnostic tool, because it is minimally invasive. A ductal

carcinoma of ectopic breast tissue is not always initially diagnosed by

FNA. It is particularly difficult to differentiate ectopic breast cancer

from lymph node metastasis in patients with adenocarcinoma [6]. A

differential diagnosis with lymph node metastasis can be established

by confirming the absence of lymph node tissue and lymphovascular

infiltration. Normal breast tissue surrounding the tumor is a com-

mon pathological finding in the majority of case reports, supporting

the histological conclusion that the tumor originated from ectopic

breast tissue [6-8]. To this end, a core needle biopsy was performed to

obtain sufficient tissue. However, in our case, normal breast tissue was

not found near the tumor, conflicting with our diagnostic confirma-

tion of the tumor originating from ectopic breast tissue. Owing to the

poor histological tissue grade, the histological distinction was diffi-

cult. The differential diagnosis of a tumor originating from the skin

adnexal gland was necessary. However, the tumor displayed no conti-

nuity with respect to the skin, originated from the deep layer, and pro-

liferated throughout the subcutaneous layer. Finally, despite the ab-

sence of normal breast tissue, we concluded that the tumor had origi-

nated from the ectopic breast tissue.

Some authors recommend ipsilateral radical mastectomy as the sur-

gical treatment of choice. However, Cogswell and Czerny [9] argued

that there is no difference in the recurrence rate between radical mas-

tectomy and local excision with axillary dissection, insisting that local

excision with axillary node dissection is the treatment of choice. Evans

and Guyton [1] are also opposed to the benefit of mastectomy over ax-

illary dissection. Mastectomy should be conducted when a differential

diagnosis is difficult [10]. According to case reports from Japan from

1998 until today, local excision was conducted in 79.2% of cases, where-

as mastectomy was conducted in 20.8% of cases [7]. In the present case,

wide excision with a clear cut margin resulted in local recurrence and

distant metastases. However, considering the rarity of the disease itself

and the lack of follow-up or staging data, it was very difficult to evaluate

the outcome and prognosis of either surgical treatment.

Lymph node metastasis is considered to be one of the most signifi-

cant prognostic factors and is likely to occur through the surrounding

anatomical structures that are in close proximity [7]. As was shown in

our case, axillary node metastasis revealed a poor prognosis with rap-

id recurrence and distant metastases.

Initially, an axillary invasive ductal carcinoma that originates from

ectopic breast tissue is prone to be misdiagnosed as a benign inflamma-

tory disease. Delayed diagnosis is an important concern. To confirm the

diagnosis, we should perform a careful evaluation using imaging and

pathological testing. Then, an appropriate choice of surgical treatment is

important. If advanced node metastases is present, as was the case for

our patient, aggressive surgical treatment options such as a mastectomy

should be performed. Due to its rarity, further studies are needed to ac-

curately understand this disease and assess treatment results.

CONFLICT OF INTEREST

The authors declare that they have no competing interests.

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