Immunocytochemistry for diagnostic cytopathology-A practical guide.

Area of Science:

• Cytopathology
• Immunohistochemistry
• Oncology

Background:

• Cytological specimens are crucial for diagnosis and prognostication, especially when minimally invasive.
• Equivocal cytomorphology often necessitates ancillary testing for definitive diagnosis and clinical management.
• Immunocytochemistry (ICC) is a primary ancillary tool for resolving diagnostic uncertainties in cytopathology.

Purpose of the Study:

• To provide a practical guide for utilizing immunocytochemistry (ICC) in diagnostic cytopathology.
• To cover common non-hematolymphoid diagnostic scenarios across various body sites.
• To emphasize judicious use of ICC markers for accurate diagnosis and preservation of material for further testing.

Main Methods:

• Review of current literature and clinical practices for ICC application in cytopathology.
• Focus on non-hematolymphoid neoplasms encountered in diagnostic settings.
• Discussion of marker selection, panel customization, and interpretation strategies.

Main Results:

• ICC is essential for differentiating overlapping morphological features and determining cell lineage or metastatic origin.
• Multiple immunomarkers, often in customized panels, are frequently required to rule out differential diagnoses.
• Strategic use of ICC preserves precious sample material for subsequent molecular or targeted therapy testing.

Conclusions:

• ICC is an indispensable tool in modern diagnostic cytopathology, particularly for non-hematolymphoid lesions.
• Tailored ICC panels, guided by clinical context and morphology, are critical for accurate diagnosis.
• Optimizing ICC use ensures definitive diagnoses while conserving material for advanced molecular analyses.