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Updated: Feb 13, 2026
Cell Block Preparation from Cytology Specimen with Predominance of Individually Scattered Cells
Published on: July 21, 2009
Programmed death ligand 1 testing in non-small cell lung carcinoma cytology cell block and aspirate smear
Bryce Noll1, Wei-Lien Wang1, Yun Gong1
1Division of Pathology and Laboratory Medicine, Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Background:
Immune checkpoint inhibitors targeting the programmed cell death 1 (PD-1) receptor and its ligand, programmed death ligand 1 (PD-L1), have emerged as a therapeutic approach for patients with non-small cell lung carcinoma (NSCLC). PD-L1 expression, assessed by immunohistochemistry (IHC), is used to select patients for PD-1/PD-L1 inhibitor therapy. Most studies have been performed with histology specimens, with limited data available on the performance in cytology specimens. This study evaluated PD-L1 in cytology specimens and compared the results with those from paired core-needle biopsy for concordance.
Methods:
Forty-one NSCLC fine-needle aspiration cases that had paired core-needle biopsy specimens with PD-L1 IHC were selected. A Papanicolaou-stained direct smear and a cell block section from each case were stained with a Dako PD-L1 pharmDx antibody (clone 22C3). Only slides with 100 or more tumor cells (37 smears and 38 cell blocks) were evaluated. Tumor proportion scores (TPS) were assessed on the basis of the partial/complete membranous staining of tumor cells and were correlated with those of paired core-needle biopsy.
Results:
All 9 smears that were negative for PD-L1 staining showed 100% concordance with the paired core-needle biopsy, whereas 28 smears with PD-L1 expression showed a similar TPS, except for 1 smear that was discordant. In contrast, 10 negative paired core-needle biopsy cases corresponded to 9 concordant negative cell blocks, whereas 1 cell block had a TPS of 1% to 5%. The remaining 28 cell blocks demonstrated PD-L1 expression, with 22 cases showing a TPS similar to that of the paired core-needle biopsy, whereas 6 cell blocks were discordant, likely because of intratumoral heterogeneity.
Conclusions:
The results show that NSCLC cytology samples evaluated for PD-L1 have high concordance with paired core-needle biopsy samples and can be used for assessing PD-L1 expression. Cancer Cytopathol 2018;126:342-52. © 2018 American Cancer Society.
Insights
Cytology samples of non-small cell lung carcinoma (NSCLC) show high concordance with core-needle biopsies for programmed death ligand 1 (PD-L1) expression. This confirms cytology specimens are reliable for selecting patients for PD-1/PD-L1 inhibitor therapy.
Area of Science:
- Oncology
- Immunotherapy
- Pathology
Background:
- Immune checkpoint inhibitors targeting programmed cell death 1 (PD-1) and programmed death ligand 1 (PD-L1) are crucial for non-small cell lung carcinoma (NSCLC) treatment.
- PD-L1 expression, typically assessed by immunohistochemistry (IHC) on histology specimens, guides patient selection for these therapies.
- Limited data exist on PD-L1 assessment in cytology specimens, necessitating further investigation.
Purpose of the Study:
- To evaluate the performance of PD-L1 assessment in NSCLC cytology specimens.
- To compare PD-L1 expression results from cytology samples with paired core-needle biopsy specimens.
- To determine the concordance rate between cytology and biopsy for PD-L1 evaluation.
Main Methods:
- Forty-one NSCLC cases with paired core-needle biopsy and PD-L1 IHC were analyzed.
- PD-L1 expression was assessed on Papanicolaou-stained direct smears and cell blocks using Dako PD-L1 pharmDx antibody (clone 22C3).
- Tumor proportion scores (TPS) were determined based on membranous staining and correlated with paired core-needle biopsy results.
Main Results:
- Smears showed high concordance with paired biopsies, with only 1 discordant case out of 37 evaluated.
- Cell blocks demonstrated good concordance, with 22 out of 28 expressing PD-L1 similarly to biopsies; 6 were discordant, potentially due to heterogeneity.
- Negative PD-L1 staining in smears showed 100% concordance with biopsy results.
Conclusions:
- Cytology samples, including direct smears and cell blocks, are reliable for assessing PD-L1 expression in NSCLC.
- High concordance between cytology and core-needle biopsy suggests cytology can be used for patient selection for PD-1/PD-L1 inhibitor therapy.
- These findings support the utility of cytology specimens in guiding NSCLC treatment decisions.
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