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  P1.09 - Pathology (Not CME Accredited Session) (ID 941)

  • Event: WCLC 2018
  • Type: Poster Viewing in the Exhibit Hall
  • Track:
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/24/2018, 16:45 - 18:00, Exhibit Hall

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    P1.09-26 - A Case Report of Discordant Markers of Lung Cancer Tumor Cells: An Unusual Immunophenotype of Uncertain Significance (ID 12379)

    16:45 - 18:00  |  Author(s): Elias Jabbour
    • Abstract
    • Slides

    Background
    

    Introduction

    Non Small Cell Lung Cancer (NSCLC) is the most frequent type of lung tumor, with two major histological subtypes: adenocarcinomas and squamous cell carcinomas. Tissue transcription factor-1 (TTF-1) and Napsin A are expressed in up to 75%- 80% of primary lung adenocarcinomas respectively and the sensitivity of both p40 and p63 for squamous cell carcinoma is 92%. Here, we report an unusual case of NSCLC with coexisting histology within the same tumor cells.

    Case

    A 65-year-old male with 50 pack year smoking history underwent screening CT chest and was found to have a right upper lobe mass measuring 10 cm x 8.6 cm x 6.9 cm with narrowing of the right upper lobe bronchus in the posterior segment. Bronchoscopy and EBUS guided biopsy of the right paratracheal node revealed NSCLC, poorly differentiated, with TTF-1, Napsin A, P40 and P63 staining positive (70-80%) for both adenocarcinoma and squamous cell carcinoma within the same tumor cells. Subsequent Brain MRI and PET did not reveal any evidence of metastatic disease and the patient was classified as T4 N1 stage IIIB disease.

    Discussion

    The line between lung adenocarcinoma and squamous cell carcinoma has already been shaken by an uncommon adenosquamous variant, but our case represents a new histologic subtype that expands on the understanding of lung cancer. Adenosquamous carcinoma (ADSQC) of the lung is a rare classification of NSCLC with a reported incidence of 0.4-4%. Histology defined by the World Health Organization defines ADSQC as a mixed type of tumor, with each component representing greater than 10% of the entire tumor. Based on studies by Naunheim et al, the median survival of patients with stage III ADSQC was 5.0 months compared to 9.0 months with adenocarcinoma and 7.8 months with squamous cell carcinoma.

    However, our case is different, as immunohistochemistry was positive for TTF-1, Napsin A, p40 and p63 biomarkers within the same individual tumor cells, thus diagnosing an entirely different pathology. After review of the literature, this is the third case with such co-expression. This case is important as it promotes awareness of this rare pathology. Both clinicians and pathologists need to be aware of its existence, in order to prevent misdiagnosis and treatment delay in what may be hypothesized as an aggressive tumor. As more cases emerge, further studies can determine incidence, prognosis, presence of driver mutations, and treatment implications.

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