title: Amelanotic acral melanomas: clinicopathological, BRAF mutation, and KIT aberration analyses.
abstract: BACKGROUND
  Amelanotic acral melanoma (AAM) is very rare and difficult to diagnose both clinically and pathologically. Complete-type AAM shows no black to brown pigmentation in the lesion, whereas incomplete-type AAM shows focal or subtle pigmentation. AAM has been the subject of few investigations.
  
  
  OBJECTIVE
  We analyzed the clinicopathological features, BRAF mutations, and KIT aberrations in 35 Korean AAM cases.
  
  
  METHODS
  We included 28 cases of complete-type and 7 cases of incomplete-type AAM.
  
  
  RESULTS
  In all, 26 AAMs (45.7%) were located on the feet of patients, 21 of which (82.9%) showed ulceration. Sixteen cases developed in subungual areas. Nodular melanoma was the most common histopathological subtype (63.6%). The most frequent cell types affected were epithelioid and spindled. HMB-45 staining was strongly positive in 66.7% of AAMs; 4 (12.1%) were negative for HMB-45, and 3 of these were complete-type AAMs. Of 33 total patients, BRAF mutations were detected in 2 AAM cases, and KIT aberrations were present in 11 cases (33.3%). Four cases (12.1%), all of which were complete-type AAMs, had KIT mutations. KIT aberrations were weakly correlated with c-kit staining. Twenty patients were TNM stage I or II, and mean survival was 30.14 ± 4.54 months.
  
  
  CONCLUSIONS
  The study is limited by the small number of patients.
  
  
  CONCLUSIONS
  Physicians should be aware of rare and hard-to-diagnose AAMs. We expect that tyrosine kinase inhibitors would be effective for KIT-mutated patients with complete-type AAMs.
authors: Department of Pathology, Chonnam National University Medical School, Gwangju, Korea.
authors: Yoo Duk
authors: YD
authors: Choi
authors: Department of Dermatology, Chonnam National University Medical School, Gwangju, Korea.
authors: Seung Min
authors: SM
authors: Chun
authors: Department of Dermatology, Chonnam National University Medical School, Gwangju, Korea.
authors: Sun A
authors: SA
authors: Jin
authors: Department of Dermatology, Chonnam National University Medical School, Gwangju, Korea.
authors: Jee-Bum
authors: JB
authors: Lee
authors: Department of Dermatology, Chonnam National University Medical School, Gwangju, Korea. Electronic address: sjyun@chonnam.ac.kr.
authors: Sook Jung
authors: SJ
authors: Yun
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D018328:Melanoma, Amelanotic / Q000235:genetics* / Q000473:pathology*; D009154:Mutation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics*
chemical_list: D019009:Proto-Oncogene Proteins c-kit; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: AAM; AJCC; American Joint Committee on Cancer; BRAF mutation; HMB-45; KIT mutation; PCR; acral melanoma; amelanotic acral melanoma; amelanotic melanoma; polymerase chain reaction; prognosis