Introduction
The mammary gland is the biggest gland of the skin. It is a functional organ and a sweat gland that develops in women but remains underdeveloped in men. The vulva (external genital area in women) region is considered a very rare site for the occurrence of ectopic mammary gland tissue. The most common site of occurrence is the axilla. Areas outside the milk line where mammary ectopism occurs are the posterior neck region, face, upper extremities, inguinal region, arms, hips, thoracic region, shoulders, lateral and posterior thigh, buttock, and abdominal region. They occur less frequently in isolated situations or along with the axillary breast tissues. They emit a pattern of autosomal dominant inheritance with incomplete penetrance, but mainly they occur in familial forms or random instances.
Vulvar mammary ectopism is a hormone-sensitive condition that enlarges and becomes more evident during puberty, pregnancy, and lactation. Other times it may remain invisible throughout puberty or pregnancies. Due to their small size in children, the accessory tissue mass cannot be identified in them. The prognosis of an ectopic tissue varies in pre, and post-menopausal women as ectopic tissues of older women encounter neoplastic changes more than the rest.
What Is Vulvar Mammary Ectopism?
The vulva is an outer part of a female genital area. It includes the clitoris, labia minora, and labia majora. Ectopism means being in a strange place or position. So vulvar mammary ectopism is a congenital condition seen when the mammary gland tissue occurs in a strange place, the vulva. These accessory mammary glands are modified sweat glands.
How Does Vulvar Mammary Ectopism Occur?
Ectopic mammary tissue, also known as accessory breast tissue, persists through the development of an embryo along the ectodermal primitive milk streaks. In embryological development in the fifth week, the bilateral primitive embryonic milk line extends from the axillary region to the groin area. In women, the lower extensions of the embryonic milk line bilaterally cross the vulva region. The earliest embryological form of the milk line is the mammary ridge which undergoes complete atrophy in the later period. However, some short segments remain in the pectoral region, eventually giving rise to normal breasts. Mammary ridges that fail to atrophy give rise to supernumerary or ectopic breasts like the vulvar mammary ectopism. Mammary glands arising from these mammary ridges are modified sweat glands. In some cases, ectopic breasts can also develop outside the milk lines.
What Are the Symptoms Associated With Vulvar Mammary Ectopism?
When hormonal changes occur due to puberty, lactation, or pregnancy, functional activity begins in the dormant tissue causing the symptoms. Some symptoms are vulvar swelling, abscesses, discomfort, pain, or lacteal secretions. These changes are mostly periodic, occurring alongside menstruation.
Are Vulvar Breasts the Same as Normal Breasts?
Vulvar breasts undergo the same pathological and physiological changes as normal breasts.
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Physiological Changes - Vulvar breasts respond to the hormonal changes that occur during puberty, menstruation, lactation, and pregnancy resulting in discomfort and swelling. During pregnancy, the levels of progesterone, estrogen, and prolactin increase leading to the proliferation and growth of the breast tissue. During postpartum, with the beginning of lactogenesis, prolactin levels increase, and progesterone and estrogen levels undergo withdrawal. The production is revived only with the baby's suckling, so the prolactin levels remain stable. Similar changes can occur in the ectopic breast tissue as well.
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Pathological Changes - Neoplastic changes (benign and malignant) in the normal breast can also occur in the vulvar breasts. Neoplastic changes are mostly seen in the ectopic tissues of older women.
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Benign Changes - Benign changes include fibrocystic changes. The main component of a fibrocystic lesion is the cysts. The emergence of a cyst is due to the influence of estrogen on the breast duct's obstruction and the tissue's proliferation. The epithelial secretions that occur due to the obstruction lead to the formation of cysts. Cysts can be macroscopic or microscopic in structure.
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Malignant Changes - Some malignant changes in the condition are lobular, phyllodes, ductal, mucinous adenocarcinoma, sarcomatous changes, and fibroadenoma. However, carcinoma occurring in ectopic breast tissue is rare.
How Can Vulvar Mammary Ectopism Be Diagnosed?
Vulvar mammary ectopism can be diagnosed through various means. Some are:
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Clinical Findings - When a fast-growing, well-encapsulated tissue is noted in the vulvar region right after delivery or during lactation. It indicates ectopic breast tissue. Clinically, it can be confused with swelling like a lipoma, as both contain adipose tissue, and since the nipple and areola are not visible.
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Histopathological Examination - Histopathological examination of tissue is done for a definitive diagnosis. Histopathology shows glands with a myoepithelial component containing a cuboidal epithelial lining firmly fixed to a fibrous stroma. In some cases, mammary parenchyma, nipple, and areola might also be present.
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Biopsy - Punch biopsy should be considered before the excision of a lesion. The biopsy is a less invasive method, even though there are chances of interpretation and sampling errors.
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Imaging Studies - Imaging modalities like ultrasound and MRI (magnetic resonance imaging) scans are used to investigate the vulvar mass.
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Ultrasound - Ultrasound is used for the evaluation of the vulvar mass.
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Magnetic resonance imaging (MRI) - MRIs can provide the finest high-resolution vulvar tissue images, helping distinguish and evaluate the mass.
Vulvar mammary ectopism must also be regarded as a part of the differential diagnosis of other masses in the vulvar area. Some benign masses are Bartholin gland disorders, sebaceous cysts, lymphangiomas, lipomas, and hidradenoma papilliferum, and malignant masses include melanoma, squamous cell carcinoma, metastatic disease, adenocarcinoma arising from the Bartholin gland and Paget's disease.
What Are the Treatment Options for Vulvar Mammary Ectopism?
Since vulvar mammary ectopism is a potent source of numerous diseases and does not serve any proper function in humans, it should be removed once found. Pathologic confirmation and excision are recommended for appropriately treating ectopic breast tissue lesions.
Surgical Intervention:
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Surgical excision is suggested if the condition is symptomatic. It is also done when it presents as a cosmetic issue.
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In cases with benign pathology, local excision is performed 90% of the time, and in cases of malignant pathology, excision is performed in 43% of cases.
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Needle biopsy must be considered for histologic confirmation before the excision procedure.
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Liposuction is another surgical method that is performed.
Conclusion:
Vulvar mammary ectopism is a congenital condition seen more in women than men. It is an unusual condition that occurs when the mammary gland tissue develops in the vulva region. It is mostly asymptomatic in children and symptomatic in the adult population. If symptomatic, the appropriate treatment option for the condition is surgical intervention.
