Image Letter

The Bork-Baykal Phenomenon in Congenital Melanocytic Nevus

Author Affiliation(s)


The Bork-Baykal phenomenon is a new entity that was first reported in large congenital melanocytic nevus 2015 and classified as a specific variant of congenital melanocytic nevus (CMN). Afterward, this rare feature was reported in other skin disorders reflecting the different embryologic developmental periods of the nipple-areola complex (NAC) with the surrounding skin. Preserving of the NAC appears to bowl over the clinicians both in congenital and acquired skin disorders.

Keywords : Bork-Baykal phenomenon, congenital nevus, melanocytic nevus, dermoscopy

Case Presentation

A 6-month-old girl was admitted to our outpatient clinic for dermoscopic examination of a large congenital melanocytic nevus on chest (CMN). Dermatological examination revealed 15×15 cm sized, light-dark brown, multicomponent CMN with 2 excision scars over the left breast. Nipple and areola were not involved ( Figure 1A ). Dermoscopic examination revealed a whitish homogenous area surrounded by a brown homogenous area and dark brown, symmetrical reticular lines ( Figure 1B ).

Figure 1 .

(A) 15×15 cm sized, light-dark brown, multicomponent CMN with two excision scars over the left breast without the involvement of the nipple and areola. (B) Whitish homogeneous area surrounded by brown homogeneous area and dark brown, symmetrical reticular lines.

Teaching Point

Sparing of the nipple-areola complex (the Bork–Baykal phenomenon) was first reported by Baykal et al in 8 cases of large congenital melanocytic nevus (CMN) sparing the areola [ 1 ] . 2 years later, Happle referred to this entity as “the Bork-Baykal phenomenon: a new and rarely seen entity referring to the nipple-sparing nevus of the breast”. Medium and large CMNs are a subtype of hamartomas that present at birth. Their peculiar appearance was linked to the different histopathological features and embryologic developmental periods of the affected tissues and the nipple-areola complex [ 2 ] .


  1. Large Congenital Melanocytic Nevus on the Breast Sparing the Nipple and Areola Baykal C, Solakoğlu S, Polat Ekinci A, Yazganoğlu KD. Pediatr Dermatol.2015;32:514-517. CrossRef PubMed
  2. Reassessing the Biological Significance of Congenital Melanocytic Nevi Argenziano G, Caccavale S, Brancaccio G, Moscarella E, Piccolo V, Lallas A. Dermatol Pract Concept.2020;10(3):e2020068. CrossRef PubMed

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