title: Clinicopathological Features and Immunohistochemical Alterations of Keratinocyte Proliferation, Melanocyte Density, Smooth Muscle Hyperplasia and Nerve Fiber Distribution in Becker's Nevus.
abstract: BACKGROUND
  Although Becker's nevus (BN) is a relatively common disease, the systematic studies of clinicopathological and immunohistochemical results are poorly reported.
  
  
  OBJECTIVE
  To investigate the clinicopathological features and immunohistochemical alterations of keratinocyte proliferation, melanocyte density, smooth muscle hyperplasia and nerve fiber distribution in BN.
  
  
  METHODS
  Clinical and pathological data were collected in 60 newly-diagnosed BN cases. Immunohistochemical stain of Ki-67, Melan-A, keratin 15, smooth muscle actin and protein gene product 9.5 was performed in 21 cases.
  
  
  RESULTS
  The median diagnostic and onset age was 17 and 12 years, respectively. Skin lesions usually appeared on the upper trunk and upper limbs. The pathological features included the rete ridge elongation and fusion and basal hyperpigmentation. Epidermal Ki-67, Melan-A and keratin 15 expression and dermal nerve fiber length were significantly higher in lesional and perilesional skin than in normal skin (p<0.05~0.01), while smooth muscle actin expression was upregulated only in skin lesion (p<0.05).
  
  
  CONCLUSIONS
  Although the clinical diagnosis of BN is often straightforward, histopathology is helpful to differentiate from other pigmentary disorders. The hyperproliferation of keratinocytes, melanocytes, arrector pili muscle and dermal nerve fibers could be involved in the pathogenesis of BN.
authors.affiliation: Department of Dermatology, Affiliated Hospital of Guangdong Medical University, Guangdong, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Sheng
authors.affiliation: Department of Dermatology, Affiliated Hospital of Guangdong Medical University, Guangdong, China.
authors.forename: Yun-Long
authors.initials: YL
authors.lastname: Cheng
authors.affiliation: Department of Dermatology, Affiliated Hospital of Guangdong Medical University, Guangdong, China.
authors.forename: Chuan-Chuan
authors.initials: CC
authors.lastname: Cai
authors.affiliation: Department of Dermatology, Gaobu Hospital of Dongguan, Guangdong, China.
authors.forename: Wei-Jin
authors.initials: WJ
authors.lastname: Guo
authors.affiliation: Department of Dermatology, Affiliated Hospital of Guangdong Medical University, Guangdong, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Dermatology, Affiliated Hospital of Guangdong Medical University, Guangdong, China.
authors.forename: Ge
authors.initials: G
authors.lastname: Shi
authors.affiliation: Department of Dermatology, Affiliated Hospital of Guangdong Medical University, Guangdong, China.
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Fan
keywords: Becker's nevus; Keratinocytes; Keratins; Melanocytes