The key difference lies in the clinical information they provide. A **diagnostic biomarker**, detected by IHC, helps identify and classify a disease. It answers the question, "What is it?" For example, the presence of cytokeratin stains confirms a tumor is a carcinoma (epithelial origin), while CD20 positivity helps diagnose a B-cell lymphoma. These markers are essential for reaching a specific pathological diagnosis. A **prognostic biomarker**, also detected by IHC, provides information about the likely natural course and outcome of the disease in an untreated patient. It answers, "What is the expected outcome?" For instance, a high Ki-67 proliferation index in breast cancer or the loss of mismatch repair proteins (MLH1, PMS2) in colorectal cancer are associated with more aggressive disease and a worse prognosis, independent of treatment. Importantly, prognostic markers identify risk but do not predict response to a specific therapy. Some biomarkers can be both diagnostic and prognostic.

Break down complex topics into smaller, manageable chunks for easier recall.

Zambia

• Naomi Miselo – 31 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies