HISTOPATHOLOGY SPECIAL STAIN: PERIODIC ACID SCHIFF (PAS)

What this test checks

Applies a special chemical stain (Periodic Acid Schiff) to tissue sections to highlight glycogen, fungi, and certain abnormal deposits that are invisible on routine staining.

Why do people get this test?

Some infections (like fungal infections) and storage diseases are only visible with special stains. This test helps diagnose conditions that standard microscopy can miss.

When you should consider this test

• When investigating possible fungal infection in tissue
• When looking for glycogen storage diseases or abnormal deposits in liver or kidney
• When routine tissue staining is inconclusive

How to prepare

No preparation needed — performed on existing tissue samples.