[436] p40 (ΔNp63): A Highly Sensitive and Specific Immunohistochemical (IHC) Marker for Diagnosing Pulmonary Squamous Cell Carcinomas (SQCC) in Fine Needle Aspirates

Adam P Vogt, Cynthia Cohen, Momin T Siddiqui. Emory University School of Medicine, Atlanta, GA

Background: The treatment of pulmonary non-small cell carcinoma has become sharply divided between the therapeutic options now devoted to squamous cell carcinoma (SQCC) and those of adenocarcinoma (ADC). Due to the increasing ability to make a diagnosis on minimal tissue, ancillary techniques such as immunohistochemistry (IHC) are needed and must be highly sensitive and specific. The popular squamous cell IHC marker p63 has demonstrated cross-reactivity with a subset of pulmonary adenocarcinomas and lymphomas, causing it to be less specific than originally thought. The IHC marker p40 (ΔNp63) is a truncated isoform of p63 that is a promising IHC marker for SQCC. In this study we have studied and compared its utility with p63 and cytokeratin 5 on fine needle aspiration (FNA) cell blocks (CB).
Design: Thirty cases of pulmonary SQCC and thirty cases of pulmonary ADC with CB were selected. IHC for p40 (ΔNp63), p63, and cytokeratin 5 were performed on all paraffin-embedded CB serial sections.
Results:

Marker expression in pulmonary squamous cell carcinoma and adenocarcinoma
Squamous cell carcinomaAdenocarcinoma
MarkerPositiveNegativePercent PositiveMarkerPositiveNegativePercent Positive
p4030/300/30100%p400/3030/300%
p6329/301/3097%p636/3024/3020%
CK529/301/3097%CK50/3030/300%




Marker expression specificity and sensitivity in non-small cell carcinoma
MarkerSpecificitySensitivityPPVNPV
p40100%100%100%100%
p6380%97%83%96%
CK5100%97%100%97%
PPV: Positive Predictive Value; NPV: Negative Predictive Value

All cases (n=30) of squamous cell carcinoma stained positive for p40 (ΔNp63). All cases of pulmonary adenocarcinoma were negative for both p40 (ΔNp63) and cytokeratin 5. Six cases (20%) of pulmonary adenocarcinoma demonstrated nuclear staining in at least 10% of malignant cells.
Conclusions: Differentiating between pulmonary SQCC and pulmonary ADC in FNA CB can sometimes be challenging. In this regard, our data support p40 (ΔNp63) to be more sensitive and specific and to possess a greater positive and negative predictive value for SQCC in comparison to p63. This study also documents that p40 (ΔNp63) does not stain ADC, which p63 does in 20% of cases. We also found that p40 (ΔNp63) shows a greater sensitivity and negative predictive value when compared to cytokeratin 5. In paucicellular CB the increased indices p40 (ΔNp63) provides may be extremely helpful in confirming the diagnosis of SQCC which may have significant therapeutic implications.
Category: Cytopathology

Monday, March 4, 2013 1:00 PM

Poster Session II # 100, Monday Afternoon

 

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