Utility of cytology microarray constructed from effusion cell blocks for immunomarker validation

Area of Science:

• Anatomic pathology
• Molecular pathology
• Oncology

Background:

• Tissue microarray (TMA) enables efficient protein-level gene expression and immunochemical marker evaluation.
• No prior studies have reported the construction and utility testing of cytology microarray (CMA) using effusion cell blocks for immunochemical marker validation.

Purpose of the Study:

• To construct a novel cytology microarray (CMA) from malignant effusion cell blocks.
• To evaluate the utility of CMA in validating immunochemical markers by comparing results with original cell block sections.

Main Methods:

• A cytology microarray (CMA) was constructed using 3 cores (0.6 mm diameter) from cell blocks of 23 malignant effusions (breast, GI tract, lung, ovary).
• Immunohistochemical staining was performed using antibodies including AE1/AE3, EMA, Ki-67, CK7, CK20, TTF-1, WT-1, ER, and PR.
• Cellularity, cell composition, staining pattern, and intensity were compared between CMA cores and original cell block sections.

Main Results:

• Tumor cell composition in CMA cores was similar to original blocks (5%-90%).
• Immunostains for AE1/AE3 and EMA showed 100% concordance. CK7, CK20, ER, PR, TTF-1, and WT-1 also demonstrated high agreement in percentage, pattern, and intensity.
• Ki-67 staining showed 84% concordance, with discrepancies attributed to low tumor burden and staining percentage in original blocks.

Conclusions:

• Three 0.6 mm cores of cytology microarray (CMA) are representative of the original cell block in terms of cellularity and antibody staining characteristics.
• CMA facilitates rapid validation of immunocytochemical markers, showing great potential for clinical research and practice.