Can novel elastin stains improve pathologic assessment of microscopic vascular invasion in lung adenocarcinoma? A reproducibility study with comparative analysis of diverse histochemical stains for elastin
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Abstract
Visceral pleural invasion (VPI), tumor cell invasion into the elastic layer of the pleura, is a standard in staging lung adenocarcinomas. Many studies have found vascular invasion (VI), tumor cells within the lumen of veins or arteries, to be as significant a negative prognostic factor as VPI. In this study, we examined whether or not the use of the elastic stains to evaluate VPI and VI led to improved assessment. A cohort of attending pathologists (A) was assigned 50 cases of lung adenocarcinoma and asked to evaluate VPI and VI using 4 stains for each case (H&E, Verhoeff’s Van Gieson, ET, and Movat Pentachrome) A second cohort of resident pathologists (B) was asked to do the same however the cases were split into 2 groups. The residents evaluated the first group of 25 cases and were then asked to watch an educational lecture regarding the stains and take an assessment. Afterwards, they evaluated the second group of 25 cases.
In cohort A, the ET did not improve accuracy or reproducibility in VI and VPI. This result led to the use of an educational video and assessment in cohort B. Overall accuracy improved in evaluation of VI and VPI in the second round (after the lecture and assessment). Similarly, reproducibility improved from fair agreement to substantial agreement in VI and to moderate agreement for VPI.
In conclusion, the ET stain improved accuracy and reproducibility of evaluation of VI and VPI in lung adenocarcinomas with educational instruction. Since the results of VI are comparable to VPI, the current standard of care in staging lung adenocarcinomas, VI should also be implemented as a standard of care with the ET used as the standard for diagnosis.