Author of

• 11866

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  P2.18 - Poster Session 2 - Pathology (ID 176)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Pathology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11887

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    P2.18-021 - How Accurate are We in Diagnosing Squamous Cell Carcinoma of the Lung in Cytology Specimens and Relevance to Molecular Testing? An Institutional Experience. (ID 3144)

    09:30 - 09:30  |  Author(s): Z. Baloch
    • Abstract

    Background
    Distinction between different subtypes of non–small cell lung carcinoma (NSCLC) particularly separating squamous cell carcinoma (SCC) from non-SCC is important due to the availability of specific targeted therapy based on histologic subtypes. Recent molecular testing guideline for selection of lung cancer patients for epidermal growth factor (EGFR) and anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor therapy from the College of American Pathologists (CAP), International Association for the Study of Lung Cancer (IASLC) and Association for Molecular Pathology (AMP), recommend that in the setting of fully excised lung cancer specimens, EGFR and ALK testing is not recommended in lung cancers that lack any adenocarcinoma component, such as pure SCC (Lindeman et al, J Mol Diagn 2013, 15:1-39). However, more than two-thirds of lung cancer presents as advanced stage disease and cytology specimens may only be available in most of these cases. Accurate distinction between SCC and non-SCC can be challenging in these cytology specimens due to limited cellularity. We report our institutional experience regarding the diagnostic accuracy of classifying SCC in cytology preparations compared with histopathological follow-up.

    Methods
    A retrospective review of the cytology specimens diagnosed as squamous cell carcinomas was carried out from January 2011 – June 2012 from our cytopathology and surgical pathology databases. All cases were correlated with subsequent histopathological diagnoses, immunohistochemical (IHC) and molecular analyses.

    Results
    A total of 200 histopathological specimens diagnosed as squamous cell carcinoma (SCC) were retrieved from our electronic medical records. 30 were excluded due to multiple specimens from the same patient. Corresponding cytology specimens including fine needle aspiration (FNA) specimens, bronchial brushings and bronchial washings were available in 88/170 (52%) cases. Out of these 88 cytology specimens, a diagnosis of malignancy was made in 58 (66%) specimens; these were subcategorized into (1) definite diagnosis of malignancy (32/58=55.2%), (2) favor tumor subtype (14/58=24.1%), (3) unclassified (9/58=15.5%) and (4) suspicious for malignancy (3/58=5.2%). Overall, the diagnoses of malignancy was made in 57/58 (98.3%) while the accurate diagnoses of squamous cell carcinoma was made in 52/55 (95%) cytology specimens. IHC was employed in cases 21/88 (23.9%). Molecular testing was performed on 12/170 (7%) specimens. Molecular testing was successful in these cases with mutations identified in two cases.

    Conclusion
    Our study demonstrates that cytology specimens are an excellent source of making a reliable, quick and accurate diagnosis of lung squamous cell carcinomas in 95% of cases and can serve as an excellent source for IHC and molecular analyses, if necessary.