Congenital anomalies

Supernumerary / accessory tissue

Topic Completed: 1 February 2010

Minor changes: 31 December 2020

Copyright: 2002-2021,, Inc.

PubMed Search: Supernumerary nipples or breasts / accessory glandular tissue

Hind Warzecha, M.D.
Page views in 2020: 3,870
Page views in 2021 to date: 3,613
Cite this page: Warzecha H. Supernumerary / accessory tissue. website. Accessed September 20th, 2021.
Definition / general
  • Persistent epidermal thickenings along milk line from axilla to perineum / vulva, due to clusters of primordial breast cells that fail to involute
  • Ectopic tissue may be combinations of breast glandular tissue and nipple
  • References: eMedicine: Supernumerary Nipple [Accessed 20 August 2018]
  • Also called pseudomamma
  • Polythelia (3+ nipples) is more common than polymastia (ectopic breast tissue)

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Milk lines

  • Occurs in 2 - 6% of females and 1 - 3% of males
  • Accessory nipples: thorax or abdomen (65%) and axilla (20%) are most common; back, buttock, face and neck are less common
  • Accessory glandular tissue: axilla most common
  • May be more common on left side in males (Eur J Pediatr 1998;157:821)
Clinical features
Case reports
  • Usually no surgery
  • Surgery performed for cosmetic reasons or if a lesion has developed in the breast tissue
Clinical images

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Adolescent boy

Adolescent girl (bilateral)

Nipples anterior to axilla

Nipple on shoulder

Nipple on foot

Microscopic (histologic) description
  • Supernumerary nipple has same features as regular nipple, including hyperpigmentation, slight hyperkeratosis, pilosebaceous structure of Montgomery tubercles, smooth muscle, Toker cells (J Cutan Pathol 2003;30:256), possibly breast lobules and ducts
Microscopic (histologic) images

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12 year old girl with axillary mass

Differential diagnosis
  • Lentigos and melanocytic nevi: have melanocytic nests; no pilosebaceous structure of Montgomery tubercles, no smooth muscle organized as with nipple, no Toker cells and no breast glandular tissue
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