title: Gastrointestinal stromal tumors (GISTs): role of CD 117 and PDGFRA Golgi-like staining pattern in the recognition of mutational status.
abstract: OBJECTIVE
  to determine whether potential correlations between CD117 and PDGFRA might serve as an indication for targeted therapies.
  
  
  METHODS
  immunohistochemical expression of CD117 and PDGFRA was evaluated in 99 paraffin-embedded GISTs in conjunction with KIT and PDGFRA mutational status.
  
  
  RESULTS
  CD117-positive staining was noted in 93 out of 99 cases. The predominant staining pattern was cytoplasmic, either with or without membrane accentuation; in 44.5% of cases, a clear Golgi-like pattern was evident. Correlations were found between KIT mutation and both CD117 expression (p = 0.006) and Golgi-like pattern (p = 0.026). Cytoplasmic PDGFRA-positive staining was detected in 87% of cases, both with and without membrane accentuation; in 8% cases an evident Golgi-like staining pattern was observed. A significant correlation was noted between PDGFRA mutations and Golgi-like staining pattern (p = 0.001). Moreover, 95% of PDGFRA-positive GISTs were also CD117-positive, suggesting that expression of the two markers is not mutually exclusive; most of these had mutations in KIT exon 11. PDGFRA-positive/CD117-negative tumors had mutations in PDGFRA, mainly in exon 18. PDGFRA-negative/CD117-negative staining was observed in 15% of cases, all of which displayed mutations in KIT exon 11. CD117-positive/PDGFRA-negative cases were characterized by mutations in KIT, mainly in exon 11.
  
  
  CONCLUSIONS
  CD117 and PDGFRA staining are not exclusive, and the presence of a Golgi-like staining pattern for either, whilst not pathognomonic, is highly suggestive of KIT and PDGFRA mutated GISTs, respectively, and may be used with some reservations as an alternative indication for prescribing targeted therapies.
authors.affiliation: Department of Pathology, Hospital Universitario Virgen Macarena, Seville, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Jaramillo
authors.forename: María José
authors.initials: MJ
authors.lastname: Ríos-Moreno
authors.forename: Alicia
authors.initials: A
authors.lastname: Hernández
authors.forename: Joaquín
authors.initials: J
authors.lastname: Amérigo
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Trigo-Sánchez
authors.forename: Ricardo
authors.initials: R
authors.lastname: González-Cámpora
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004252:DNA Mutational Analysis; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis* / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D046228:Microarray Analysis; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D016612:Paraffin Embedding; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics*; D013194:Staining and Labeling; D055815:Young Adult
chemical_list: D019009:Proto-Oncogene Proteins c-kit; D020796:Receptor, Platelet-Derived Growth Factor alpha