A painful perineal lump: an unusual case of ectopic breast tissue

Abstract

We report the case of a 40-year-old lady who presented with an episodically painful perineal lump. Clinical and radiological investigations were inconclusive. Excision biopsy confirmed an ectopic breast mass. Ectopic breast tissue is difficult to diagnose but close attention to clinical findings can help to guide further investigation and diagnosis.

Accessory breast tissue, also known as polymastia, occurs due to the eruption of extra breast tissue usually along the milk line, which extends from the axilla to the groin. Although the location of the breast tissue is determined during embryonic life, it may not become apparent until puberty, lactation or later in life.¹ Accessory breast tissue is usually idiopathic but familial cases have also been reported. In the absence of areola and nipple, and occurring in areas such as the face, neck, upper arm, back, perineum or thigh as a palpable fullness, making a clinical diagnosis of polymastia is difficult.

Accessory breast tissue may range from a subcutaneous focus of tissue to a full accessory breast complete with areola and nipple. In 1915 Kajava published a classification system for supernumerary breast tissue:^2,3

• >Class I: Complete breast with nipple, areola and glandular tissue
• >Class II: Nipple and glandular tissue but no areola
• >Class III: Areola and glandular tissue but no nipple
• >Class IV: Glandular tissue only
• >Class V: Nipple and areola but no glandular tissue (pseudomamma)
• >Class VI: Nipple only (polythelia)
• >Class VII: Areola only (polythelia areolaris)
• >Class VIII: A patch of hair only (polythelia pilosa)

Patients usually only seek advice when accessory breast tissue is troublesome or cosmetically undesirable. Management should be patient centred involving adequate assessment, with appropriate investigation and treatment.

Case history

A 40-year-old lady with a history of cyclical breast pain was referred to the gynaecology department by her general practitioner with a lump in the right vulval region close to the perineal body that had been increasing in size over a 2-month period. The lump was associated with intermittent episodes of pain and tenderness. The patient had a normal mammogram history and bilateral multiple microcysts on breast ultrasound. Treatment with antibiotics and analgesia was initiated for a presumed infected Bartholin’s cyst. On examination, the lump was soft and oval in shape, measuring 3.5cm x 4.5cm. The lump was not attached to the overlying skin, which was normal, and on bimanual examination extended deep into the perineum. On review, it was felt that the perineal lump was solid rather than a cyst so the patient was referred to the general surgery department.

Ultrasound of the perineal lump confirmed a subcutaneous soft tissue mass, suggesting a lipoma or fibroma. Pre-contrast magnetic resonance imaging (MRI) revealed a well defined hypointense lesion. Post-contrast MRI using gadolinium on a fat saturated T1 weighted axial sequence showed homogenous enhancement, giving a possible diagnosis of an angiomyxoma, angioleiomyoma, neurofibroma, leiomyoma or papillary hidradenoma (Figs 1 and 2).

Figure 1.

Coronal T1 weighted pre-contrast magnetic resonance imaging of perineum shows a well defined, oval shaped, hypointense lesion to the right of the midline

Figure 2.

Axial gadolinium-enhanced, fat-suppressed T1 weighted magnetic resonance imaging of perineum shows homogenous enhancement of the lesion indicated by the white arrow

Following investigation, the patient underwent an excision biopsy under general anaesthetic. Postoperative histology demonstrated multiple cystic and duct lobular units consistent with breast tissue (Fig 3). On case review, the temporal pattern of the pain associated with the lump in the months preceding excision closely resembled that of the patient’s breast pain.

Figure 3.

Multiple cystic and duct lobular units consistent with breast tissue

Discussion

Accessory breast tissue can present anywhere along the embryological mammary streak or at ectopic sites. The incidence of polymastia varies from 0.4–6% in women and 1–3% in men. Where accessory breast tissue occurs at ectopic sites, diagnosis is rarely made on clinical grounds. Imaging of the lump is usually required³ and, in certain cases, image guided biopsy to confirm the diagnosis. In cases where diagnosis of ectopic breast tissue is confirmed with image guided biopsy, liposuction is a feasible option.⁴

In our case there was a diagnostic dilemma, both on clinical and radiological grounds. Our patient’s initial presentation with a painful perineal lump made clinical diagnosis difficult. MRI of the mass did not show the characteristic signal intensity and contrast enhancement of normal breast tissue that is suggested in the literature.⁵ Furthermore, the presence of prominent pelvic veins around the mass made image guided biopsy problematic. Diagnosis was only established with an excision biopsy, which confirmed ectopic breast tissue.

This case highlights the importance of close clinical assessment (including a detailed history) in addition to radiological and pathological findings for establishing a diagnosis of accessory breast tissue. Had closer attention been paid initially to the cyclical nature of the pain associated with the lump, the diagnosis may have emerged sooner, reassuring the patient and guiding ongoing management.