Unilateral Ectopic Breast Tissue in the Vulva - A Diagnostic Dilemma

ABSTRACT

Ectopic breast tissue is a rare condition caused by remnants of the mammary ridges that fail to involute during embryologic development. Clinical presentation of vulval breast tissue is highly variable and diagnosis is ultimately made by tissue biopsy and histopathological examination. Since this ectopic tissue serves no function, surgical excision is recommended. Vulval ectopic breast tissue is an extremely rare case, especially in midlife. Because of its rarity in occurrence and unusual site, here we report a case of unilateral ectopic breast tissue on the vulva in an adult midlife female.

INTRODUCTION

Ectopic or accessory breast tissue may occur anywhere along the embryonic line which runs from anterior axillary folds to the inner thigh. Incomplete involution anywhere along the primitive milk streak could result in accessory or ectopic mammary tissue. The most common site for ectopic breast is the axilla and rarely vulva. These ectopic mammary tissues can undergo the same pathological changes as normal breasts, both benign and malignant, and need surgical excision. Diagnosis is only by histopathology. In this report, we present a case of unilateral swelling in the vulva, which mimicked as lipoma but was diagnosed as ectopic breast tissue on histopathology.

CASE REPORT

A 43-year-old female patient referred with a history of swelling at the right side vulva for 2 years. Initially, it was of the size of peanut but gradually increased in size and attained the present size of lemon. The patient had sought medical advice as the swelling had gradually increased in size. Local examination revealed single, ovoid, 5 cm × 3 cm cystic, nontender, well-defined swelling on the upper end of the right labia majora, which was not associated with any discharge. The overlying vulval skin was intact. Swelling was not fixed to the skin or underlying structures and no inguinal lymphadenopathy was felt. Ultrasound revealed [Figure 1] well-defined heterogeneously echoic solid lesion 34 mm × 24 mm × 19 mm (vol 8cc) arising from right labia showing internal vascularity suggestive of Right labial cyst. vulval breast although congenital may remain quiescent during puberty and pregnancy as in our case [Figure 2]. We suspected it to be a lipoma, but to our surprise, tissue examination revealed features of normal breast tissue [Figure 3]. Postoperatively, she recovered well and was followed up in the outpatient department. On follow-up, the wound had healed and she was discharged from follow-up.

Figure 1.

Ultrasound

Figure 2.

Gross section

Figure 3.

Histopathology of the tissue

DISCUSSION

Ectopic mammary gland tissues occur in about 2%–6% of women and 1%–3% of males. About a third of these have more than one area of supernumerary tissue growth. Occurrence rates vary widely on the basis of ethnicity and gender, ranging from as low as 0.6% in Caucasians to as high as 5% in Japanese females. Primary breast cancer in ectopic breast tissue is reported as 0.3%–0.6% of all breast cancer.[1]

Ectopic breast tissue is a residual tissue that persists during embryologic development. Most of the reported cases in the literature tend to occur at the upper end of the embryonic ridge, where very few cases were arising from the inferior end of the embryonic mammary ridge.[2] The vulva is considered a rare site for ectopic breast tissue. Clinically, it gets commonly confused with lipoma and also malignant neoplastic lesions. Diagnosis is confirmed only after histopathological assessment of tissue.[3]

Supernumerary breast or accessory breast or ectopic breast tissue occurs along the mammary milk lines, extending bilaterally from the midaxillae inferiorly to the medial groins. In women, the inferior extensions of the milk lines traverse the vulva bilaterally. The embryologic mammary ridges later undergo complete atrophy except for two short segments that remain in the pectoral region to give rise to normal breasts. Ectopic breast tissue develops from portions of the milk ridges that fail to involute.

Polythelia, in particular, has been associated with urinary anomalies such as supernumerary kidneys, renal adenocarcinoma, polycystic renal disease, and duplicate renal arteries explained by parallel embryological development of mammary and genitourinary system.[4]

Clinical presentation of ectopic breast tissue is varied, ranging from asymptomatic, lump with pain and discomfort during menstruation, pregnancy and lactation, and psychological and cosmetic disturbance in adolescence. Most importantly, these also develop the same pathological changes as normal breast tissue, namely inflammation, fibroadenoma, phyllodes, cystosarcoma, and carcinoma.[5]

In 1915, the Kajava classification [Table 1] was developed to describe ectopic breast tissue on the basis of tissue composition.[6]

Table 1.

Kajava classification of ectopic breast tissue

Class	Description
Class 1 (polymastia)	Complete breast(s) with nipple, areola and glandular tissue
Class 2 (supernumerary breast without areola)	Nipple and glandular tissue but no areola
Class 3 (supernumerary breast without nipple)	Areola and glandular tissue but no nipple
Class 4 (mamma aberrate)	Glandular tissue only
Class 5 (Pseudomamma)	Nipple and areola but without glandular tissue ( replaced by fat )
Class 6 (Polythelia)	Nipple only
Class 7 (Polythelia areolaris)	Areola only
Class 8 ( Polythelia pilosis)	Patch of hair only

As per this system, our case belongs to class IV.

Vulval breast tissue might remain quiescent in puberty and pregnancy as in our case but grew in size later.[6] They serve no useful function but act as a potential source of diseases. Hence, prompt surgical excision after investigations should be done.[7]

In view of the risk of malignancy, especially the Kajava class 1–1V lesions, treatment includes wide surgical excision or liposuction.[8]

Judicious excision of ectopic breast tissue was suggested by Choi et al. in women with clinical features such as middle age in the fifth or sixth decade, Kajava class 1–1V, consistent growth not related to the menstrual cycle and indistinct impression clinically and on imaging.[9]

Aydogan et al. in their study on 29 cases with accessory breast tissue reported 16 patients with unilateral and 13 patients with bilateral accessory breasts. They concluded that axillary accessory breasts can be satisfactorily treated with excision, liposuction, or both.[10]

In a recent systematic review of 126 cases of vulvar ectopic breast tissue, 57.9% were benign and 42.06% were found to be malignant. Diagnosis was made on the basis of clinical findings, imaging, tumor markers, and immunohistochemistry.[11]

CONCLUSION

Ectopic breast tissue should be considered an important differential in swelling of the vulva even in midlife, although it is rare. The clinician should be aware of the presence of breast tissue when tumors are found along the mammary line. It is important to screen for urogenital anomalies when accessory breast tissue is diagnosed. Fine-needle aspiration cytology may be helpful in the preoperative diagnosis of ectopic breast tissue.

Careful screening for ectopic breast tissue should be done during routine screening for breast cancer. Treatment should be wide surgical excision followed by histopathology of specimen to confirm the diagnosis and rule out malignancy.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.