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O17 - Anatomical Pathology I (ID 128)
- Event: WCLC 2013
- Type: Oral Abstract Session
- Track: Pathology
- Presentations: 1
O17.03 - Morphological and Mucin profile of lung adenocarcinoma harboring driver mutation (ID 2523)
10:30 - 12:00 | Author(s): S. Sato
Recent advantages of molecular study reveal several subsets of lung adenocarcinoma (AdCa) with specific genetic alterations of receptor tyrosine kinase (RTK), including EGFR, ALK, RET and ROS, which are dramatically responding to targeted inhibitors for activating RTK. The goal of this study is to evaluate the correlation between genetic alteration and histologic phenotype of lung AdCa, including cell type characteristics and mucin phenotype.
319 surgically resected lung Ad CA was examined genetic alterations of EGFR by Cycleave or direct sequencing, ALK by FISH and immunohistochemistry and KRAS by PCR-RFLP and direct sequencing methods. Resected materials were reviewed detail histologic findings, using HE-stained slides of whole tumor. A histologic predominant subtype of AdCa, based on a new IASLC/ATS/ERS classification, and nuclear grading were evaluated. The mucin phenotype of AdCa was evaluated by Immunohistochemical staining, including muc1, muc2, muc5ac and muc6. The correlation between genetic alteration and histologic phenotypes was examined.
Genetic alterations of this study were 150 EGFR, 44 ALK, 9 KRAS and 116 wild-type. EGFR mutated AdCa had 55.4% lepidic- (lep), 40% papillary- (pap), 2.6% of acinar- (aci) and 2% of solid- (sol) predominant subtypes. ALK AdCa had 20.5% of lep, 36.4% pap, 18.2% aci, 22.7% sol and 2.3% micropapillary predominant subtypes. Kras mutated AdCa were 44.4% pap, 33.3% aci and 22.2% sol. All wild type AdCa were 35.3% of lep, 53.4% pap, 5.2% aci- and 6% sol. Presence of mucin producing cells was observed in 4.7, 90.9, 66.7, and 26.7% of EGFR, ALK, KRAS and wild type AdCa, respectively. EGFR and ALK showed lower nuclear grade compared to KRAS. IHC examination revealed ALK AdCa was positive for muc1, but negative for muc2, 5ac and 6, in contrast to wild type /EGFR AdCa which were positive for muc1, sometimes for muc2, muc 5ac and/or muc6.
In summary, the most common histologic phenotype of EGFR AdCa was lepidic-predominant, non-mucin producing with low nuclear grade; ALK AdCa was papillary, mucin producing with low nuclear grade, and KRAS was papillary, mucin producing with high nuclear grade. The predominant subtype-based classification of AdCa showed an incomplete correlation to a genetic abnormality. Cell type characteristics, including mucin phenotype, would be useful to predict the genetic alteration of lung AdCa, in addition to the predominant subtype which is architecture-based assessment.
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