[Quality control of immunohistochemical studies: compulsory duty or urgent need?]

Immunohistochemical study is an integral component of modern morphologic diagnostics, providing accurate marker detection and identification of molecular subtypes of malignant neoplasms. A quality control system is fundamental in the aspect of standardizing laboratory protocols, ensuring reproducibility of results and increasing the reliability of diagnostic conclusions.

Objective: To conduct a comprehensive assessment of the quality of immunohistochemical studies at the successive stages of the laboratory process (pre-analytical, analytical, post-analytical) in medical organizations that are participants of the external quality control program of the IHC Quality Control Center of Russian Medical Academy of Continuous Professional Education for 2024.

Material and methods: The present study analyzed the results of external quality control rounds initiated by the Quality Control Center. The nature and frequency of errors at all stages of immunohistochemical study, including procedures for fixation of biological material, methodology of immunohistochemical staining, and interpretation of the results obtained were evaluated. Analytical evaluation was carried out by experts in accordance with the criteria of international standards (CAP, NordiQC).

Results: The analysis of the pre-analytical stage revealed methodological inconsistencies related to the processes of fixation of biological material, to the degree of DNA degradation and to the qualitative characteristics of histologic processing. At the analytical stage, the main errors were inadequate selection of antibodies and detection systems, and insufficient validation of diagnostic protocols.

The postanalytic phase was characterized by a predominance of factors of incorrect conclusions, including errors in interpretation of HER2 status and molecular genetic subtypes of breast carcinoma. Repeated rounds of follow-up demonstrate that implementation of expert recommendations contributes to statistically significant improvements in diagnostic quality.

Conclusion: The system of external quality control of immunohistochemical studies represents a key tool to optimize the accuracy and reproducibility of morphological diagnostics. Systematic participation of laboratories in control programs, standardization of methodological approaches and improvement of professional qualification of specialists ensure minimization of diagnostic errors and increase of clinical significance of research results.