2017 Volume 56 Issue 1 Pages 9-14
Objective : We examined the effect of specimen fixation in CytoRich Red preservative fluid on the results of immunocytochemistry (ICC) of pleural fluid.
Study Design : Pleural fluid specimens were examined by ICC for calretinin and CD146 in 41 cases of pleural effusion, including 23 cases of benign mesothelial lesions, 8 cases of malignant mesothelioma, and 10 cases of lung adenocarcinoma. Cytology specimens of pleural fluid from cases of benign mesothelial lesions and lung adenocarcinoma were fixed in one of 2 different fixatives : CytoRich Red or 95% ethanol. Malignant mesothelioma cells were fixed in CytoRich Red (4 cases) or 95% ethanol (4 cases). ICC for calretinin and CD146 was assessed as positive when the average expression rate was 11% or more.
Results : Benign mesothelial cells were calretinin-positive and CD146-negative in both specimens fixed in CytoRich Red and 95% ethanol. The rate of calretinin expression in specimens fixed in CytoRich Red was significantly higher than that in the specimens fixed in 95% ethanol fixative (p<0.05). In contrast, there was no significant fixative-dependent difference in the rate of CD146 expression (p=0.15). Malignant mesothelioma was CD146-positive in specimens fixed in both fixative solutions. Although all cases of lung adenocarcinoma were calretinin-negative, 4 cases were CD146-positive.
Conclusion : The expression rates of calretinin differ depending on the fixative solution used, and a few reactive mesothelial cells also show positive immunocytochemical results for CD146. In effusion cytology, it is necessary to pay careful attention to selecting and evaluating the fixative solution, since the choice of the fixative solution influences the results of immunocytochemistry.
