Indian Journal of Pathology and Microbiology

: 2020  |  Volume : 63  |  Issue : 2  |  Page : 319--321

Anomalies in milk line: Case report of two cases

Mani Krishna1, Taiba Khan1, Asim Khan2,  
1 Department of Pathology, UPUMS, Saifai, Uttar Pradesh, India
2 Department of Pathology, VIMS, Gajraula, Uttar Pradesh, India

Correspondence Address:
Taiba Khan
Senior Resident, Room No b/206 DTH, Guest House, UPUMS, Saifai, Etawah - 206 130, Uttar Pradesh


Congenital anomalies of breast, especially polymastia and polythelia, confuse clinicians because of their varied presentations, associated renal anomalies, and pathologies arising in them. Case 1: A 30-year-old Asian Indian female presented with swelling in left inguinal region since 2 years, increased in size in last 2 months with history of milk discharge. Diagnosis of ectopic breast tissue inguinal region with lactational changes was made on fine-needle aspiration cytology (FNAC). Case 2: A 28-year-old female presented with complaints of bilateral axillary mass for 2 years which is gradually increasing in size and associated with pain and discomfort along with intrareolar polythalia (left breast). FNAC was done from both axillary swelling which came out to be the fibroadenoma in ectopic breast tissue. Both the cases are discussed because of their rarity and to screen ectopic breast tissue for any pathology during routine screening of breast.

How to cite this article:
Krishna M, Khan T, Khan A. Anomalies in milk line: Case report of two cases.Indian J Pathol Microbiol 2020;63:319-321

How to cite this URL:
Krishna M, Khan T, Khan A. Anomalies in milk line: Case report of two cases. Indian J Pathol Microbiol [serial online] 2020 [cited 2020 Jul 11 ];63:319-321
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Embryonic breast development begins during the fourth week of gestation, when ectodermal tissue forms a ridge across the ventral surface, extending from axilla toward midline of the groin. This ridge is called mammary ridge (embryonic milk line). Normally, the mammary ridge recedes, leaving only bilateral mammary tissue at the level of fourth intercostal space. Ectopic breast tissue (EBT) results from involution failure of any portion of embryonic mammary folds.[1]

The incidence of ectopic breast tissue and supernumerary (ectopic) nipple is rare and is around 0.6–6%. The most common site for ectopic nipples is just below the normal breast, and most common site for ectopic breast is the lower axilla. Ectopic breast below the umbilicus is extremely rare.[2]

Normally, this ectopic tissue is physiologically nonfunctional.[3]

EBT responds in the same way as normal breast tissue to physiological influences and also shows hormonal changes similar to normal breast. Therefore, pain, tenderness, and milk secretion can occur with fluctuating hormonal levels from puberty, menstruation, pregnancy, and lactation.

EBT is classified as follows:

  • Polymastia: glandular breast tissue in an organized ductal system, communicating with overlying skin
  • Polythelia: accessory nipples and/or areola. The presence of an areola only or patch of hair only may be further categorized as polythelia areolaris and polythelia pilosa, respectively
  • Aberrant breast tissue: disorganized secretory tissue, unrelated to the overlying skin.

We present two rare cases of ectopic breast tissue: one case is the case of ectopic breast tissue in left inguinal region presenting as mass with leaking milk in lactating female and the other case is fibroadenoma bilateral EBT presenting with bilateral axillary mass with intrareolar polythelia left breast in young female. FNAC was used as diagnostic modality.

 Case 1

A 30-year-old Asian Indian female presented with swelling in left inguinal region since 2 years. Size remained static since then and had increased in size in the last 2 months. The patient also gives the history of milky discharge from the swelling.

Examination revealed unilateral left inguinal area swelling with leaking milk. Swelling was 4 × 3 cm. Swelling is soft to cystic mobile and nontender. Clinically, diagnosis of accessory breast in inguinal region was made. Both the breast and axilla are clinically normal and patient was lactating.

Fine-needle aspiration cytology (FNAC) was used as diagnostic modality. Cytological findings revealed few small clusters of ductal epithelial cells which are round to oval cells having round to oval nuclei and moderate amount of vacuolated cytoplasm admixed with darkly stained spindle myoepithelial cells. Background shows cyst macrophages and bare bipolar nuclei [Figure 1]a and [Figure 1]b.{Figure 1}

 Case 2

A 28-year-old Indian female presented with complaints of bilateral axillary mass for 2 years, which is gradually increasing in size and associated with pain and discomfort. There was no family history of breast cancer and polymastia.

On clinical examination, 3.5 × 3.5 cm size swelling is noted in the bilateral axilla. It is firm in consistency, tender, freely mobile, and completely separate from the normal breast. Skin over the swelling is normal, with no nipple or areola made out. Both the breasts are clinically normal except left intrareolar polythelia. A provisional differential diagnosis of lipoma was made.

Routine laboratory investigations were normal. Ultrasonogram showed increased amount of fat tissue in the bilateral axilla. Ultrasonogram of abdomen and pelvis shows no renal and genital tract anomaly.

Cytological examination revealed fibroadenoma bilateral axillary mass. The patient underwent surgical resection of the mass in axilla and was totally excised. Histopathological examination revealed the diagnosis of fibroadenoma [Figure 2]a and [Figure 2]b.{Figure 2}


EBT is a congenital anomaly of the breast usually confined to the area of the embryonic milk line. Two hypotheses have been claimed on the embryogenesis of the EBT. One attributes the anomaly to the failure of regression and displacement of the milk line,[4] while the second believes it develops from the modified apocrine sweat glands.[5]

In 1915, Kajava described a classification system for supernumerary breast tissue, which is commonly used [Table 1].[6]{Table 1}

According to this classification, our first case is under class IV and our second case also lies under class IV with intrareolar polythelia.

Usually, EBT becomes noticeable only after hormonal stimulation during puberty, pregnancy, or lactation. EBT may also develop benign and malignant pathologic processes similar to those seen in normally located breast tissues, including fibrocystic disease, fibroadenoma, inflammatory disease, intraductal papilloma, lactating adenoma, and carcinoma. Incidence of carcinoma in ectopic breast tissue is only 0.2% to 0.6% and invasive ductal carcinoma is the most common histotype found in EBT.[7]

In the first case, there are lactational changes in EBT present in inguinal region and in the second case, fibroadenoma is seen in bilateral axillary EBT with intraareolar polythelia left breast.

Commonly, polymastia and polythelia occur sporadically, but familial cases have been reported. Such cases are inherited in an autosomal dominant fashion with variable penetrance although X-linked dominant transmission has also been described.[8] Supernumerary nipples can exist as a part of syndrome like Simpson–Galabi–Behmel syndrome, Char syndrome, Turner's syndrome, and fetal alcohol syndrome.[9] Studies have shown the association of polythelia and genitourinary tract malformations. Supernumerary kidneys, renal aplasia, hydronephrosis, polycystic kidney disease, duplicated renal artries, and ureter stenosis are some of the congenital malformation seen. A possible explanation lies on the fact that both regression of milk line and urogenital system development happens around third month of gestation.[10] Thus, individuals with ectopic breast tissue should undergo further investigation to rule out possible urinary tract abnormalities.

EBT are prone to have similar benign and malignant pathologies like normal breast tissue.

EBT in the absence of areola and nipple are highly misdiagnosed clinically. Common presumptive diagnosis includes lipoma, lymphadenopathy, hydradenitis, sebaceous cyst, vascular malformation, and malignancy.[11] Thorough clinical examination, radiological assessment, and FNAC are useful diagnostic modalities. Histopathology is the gold standard for confirmation, shows typical stroma, lobules and ducts are seen; however, they are often disorganized in EBT.

Excision of EBT is the definitive treatment of symptoms or cosmesis.

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Conflicts of interest

There are no conflicts of interest.


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