Modified Liquid-Based Cytology Technique for Immunocytochemistry in Effusion Specimen.

Objective: Immunocytochemistry (ICC) of serous effusion is an important tool for the diagnosis of benign and malignant cells. Our aim was to develop a modified liquid-based cytological technique for ICC (i.e., a modified LBC). Methods: Serous effusions of 110 cases were collected for cytological examination: 50 were negative for malignancy albeit benign mesothelium was found, and 60 were confirmed metastatic adenocarcinoma according to the modified LBC preparation. The latter were stained for EMA, Ber-EP4, Calretinin, and p63 then interpreted by both a cytotechnologist and a pathologist. A comparative analysis of the diagnostic results was conducted. Results: The results of the metastatic adenocarcinoma were 100% (60/60) positive for EMA and 91.7% (55/60) positive for Ber-Ep4 but negative for calretinin and p63. Cases negative for malignancy were 100% (50/50) positive for calretinin but negative for carcinoma markers. The difference between 'positive for metastatic adenocarcinoma' and 'negative for malignancy' in ICC was statistically significant (p < 0.001). Conclusion: The current study demonstrated that a panel marker, comprising EMA, Ber-EP4, and calretinin can be used for differentiating between cases of metastatic adenocarcinoma and benign mesothelium. The serous effusion specimen collected by the modified LBC technique is an effective preparation method for ICC.

Comparative study for the detection of C4d in paraffin-embedded renal allograft biopsies by immunohistochemical techniques.

BACKGROUND: Peritubular capillary complement C4d deposition is one of the criteria for diagnosis of acute humoral rejection in kidney allografts. Little information is provided for the effective technique to stain C4d protein. OBJECTIVE: To compare C4d staining results by using indirect immunofluorescence detection (IF) with immunoperoxidase methods (IP) in formalin-fixed, paraffin-embedded renal allograft tissue. MATERIAL AND METHOD: C4d protein was detected in renal allograft tissues by IF and IP methods. The antigen unmarking procedures were used including (i) heating with 0.05% citraconic anhydride in a water bath plus proteinase K digestion, (ii) heating with 10 mM citrate buffer in a microwave and (iii) digesting with proteinase K for comparing the deposition of C4d in paraffin-embedded tissues. RESULTS: The results showed that the unmarking solution containing 0.05% citraconic anhydride pH 7.4 and heating in a water bath revealed a signal enhancement in the IP method whereas the solution containing 0.05% citraconic anhydride pH 7.4 and heating in a water bath plus proteinase K digestion showed a greatly enhanced signal in the IF method. The prevalence of C4d staining detected in peritubular capillaries was 68% (17/25) and the results observed for both methods were similar. CONCLUSION: 0.05% citraconic anhydride in a water bath with or without proteinase K digestion is useful for unmasking C4d deposition in peritubular capillaries of renal allografts performed by IP and IF methods.