**Question:** The necrotic tissue and deposits of immune complexes, complement and plasma protein produce a smudy eosinophilic deposit is termed as

A. Congo red
B. Gomori's methenamine silver
C. Periodic acid-Schiff (PAS)
D. Wright's stain

**Core Concept:**

A necrotic tissue and deposits of immune complexes, complement, and plasma proteins can lead to the formation of eosinophilic deposits. These deposits are a result of the activation of the immune system and the involvement of various components such as immune complexes, complement, and plasma proteins.

**Why the Correct Answer is Right:**

The correct answer is **B. Gomori's methenamine silver**. This stain is specifically designed to visualize the eosinophilic deposits caused by immune complex deposition and complement activation. Methenamine silver reacts with proteins containing sulfur atoms, such as those found in eosinophilic deposits, resulting in a characteristic smudgy, eosinophilic deposit.

**Why Each Wrong Option is Incorrect:**

A. **Congo red** is not specific for eosinophilic deposits and is primarily used for visualizing amyloid deposits.

B. **Gomori's methenamine silver** is the correct stain for visualizing eosinophilic deposits, so excluding this option is not necessary.

C. **Periodic acid-Schiff (PAS)** is used for staining carbohydrates and glycoproteins, not specifically for visualizing eosinophilic deposits caused by immune complex deposition and complement activation.

D. **Wright's stain** is a hemosiderin stain used to visualize iron-containing particles, such as hemosiderin, not suitable for visualizing eosinophilic deposits.

**Clinical Pearl:**

Understanding the staining techniques and their specific applications is crucial for medical students and clinicians to accurately diagnose and interpret histopathological findings. Gomori's methenamine silver is a valuable tool for diagnosing conditions like systemic lupus erythematosus (SLE) where immune complex deposition and complement activation are common findings.