title: BRAF mutations in conjunctival melanoma: investigation of incidence, clinicopathological features, prognosis and paired premalignant lesions.
abstract: OBJECTIVE
  To investigate incidence, clinicopathological features and prognosis of BRAF-mutated conjunctival melanoma in Denmark. Furthermore, to determine BRAF mutations in paired premalignant lesions and evaluate immunohistochemical BRAF V600E oncoprotein detection.
  
  
  METHODS
  Data from 139 patients with conjunctival melanoma (1960-2012) were collected. Archived conjunctival melanoma samples and premalignant lesions were analysed for BRAF mutations using droplet digital polymerase chain reaction (PCR). Results were associated with clinicopathological features and compared with BRAF V600E oncoprotein stainings.
  
  
  RESULTS
  The overall incidence of conjunctival melanoma (0.5 cases/1 000 000/year) increased during the study period with 0.13 cases/1 000 000/10 years. The increase comprised a higher proportion of patients aged >65 years, epibulbar tumours and tumours developed from a primary acquired melanosis with atypia. BRAF mutations were identified in 39 of 111 (35%) cases. The rate ratio of BRAF-mutated versus BRAF-wild-type melanoma did not change over time. BRAF mutations were associated with T1 stage (p = 0.007), young age (p = 0.001), male gender (p = 0.02), sun-exposed location (p = 0.01), mixed/non-pigmented tumour colour (p = 0.02) and nevus origin (p = 0.005), but did not associate with prognosis. BRAF status in conjunctival melanoma and paired premalignant lesions corresponded in 19 of 20 cases. Immunohistochemistry detected BRAF V600E mutations with a sensitivity of 0.94 and a specificity of 1.00 in newer conjunctival melanoma samples (2000-2012, n = 47).
  
  
  CONCLUSIONS
  The incidence of conjunctival melanoma increased in Denmark over 50 years. The proportion of BRAF-mutated conjunctival melanoma was constant. BRAF mutations were identified as early events in conjunctival melanoma, associated with a distinct clinicopathological profile, similar to BRAF-mutated cutaneous melanoma. Immunohistochemical detection of BRAF can be used to assess BRAF V600E mutations.
authors.affiliation: Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.|Department of Pathology - Rigshospitalet, Copenhagen, Denmark.
authors.forename: Ann-Cathrine
authors.initials: AC
authors.lastname: Larsen
authors.affiliation: Danish Cancer Society, Research Center, Copenhagen, Denmark.
authors.forename: Christina
authors.initials: C
authors.lastname: Dahl
authors.affiliation: Danish Cancer Society, Research Center, Copenhagen, Denmark.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Dahmcke
authors.affiliation: Institute of Pathology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Johanne
authors.initials: J
authors.lastname: Lade-Keller
authors.affiliation: The Research Unit and Section of General Practice, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Volkert D
authors.initials: VD
authors.lastname: Siersma
authors.affiliation: Department of Ophthalmology, Rigshospitalet - Glostrup Hospital, Copenhagen, Denmark.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Toft
authors.affiliation: Division of Pathology, Department of Molecular and Clinical Medicine, Royal Liverpool University Hospital, Liverpool, UK.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Coupland
authors.affiliation: Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jan U
authors.initials: JU
authors.lastname: Prause
authors.affiliation: Danish Cancer Society, Research Center, Copenhagen, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Guldberg
authors.affiliation: Department of Pathology - Rigshospitalet, Copenhagen, Denmark.|Department of Ophthalmology, Rigshospitalet - Glostrup Hospital, Copenhagen, Denmark.
authors.forename: Steffen
authors.initials: S
authors.lastname: Heegaard
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003230:Conjunctival Neoplasms / Q000453:epidemiology* / Q000235:genetics / Q000473:pathology; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000235:genetics; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008545:Melanoma / Q000453:epidemiology* / Q000235:genetics / Q000473:pathology; D008548:Melanosis / Q000453:epidemiology / Q000235:genetics / Q000473:pathology; D008875:Middle Aged; D009154:Mutation; D009367:Neoplasm Staging; D009508:Nevus, Pigmented / Q000453:epidemiology / Q000235:genetics / Q000473:pathology; D016133:Polymerase Chain Reaction; D011230:Precancerous Conditions / Q000453:epidemiology* / Q000235:genetics / Q000473:pathology; D011379:Prognosis; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D055815:Young Adult
chemical_list: D004273:DNA, Neoplasm; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF mutations; PAM with atypia; conjunctival melanoma; immunohistochemistry; incidence; nevus