Amyloid deposits stain positively with all of the following except
**Core Concept**
Amyloid deposits are abnormal fibrillar proteins that accumulate in various tissues, leading to amyloidosis. These deposits are composed of insoluble proteins that resist degradation, causing tissue damage and dysfunction. Amyloidosis can be primary, secondary, or hereditary, and it affects multiple organ systems.
**Why the Correct Answer is Right**
Amyloid deposits can be identified by their unique staining properties. They stain positively with Congo Red, which exhibits a characteristic green birefringence under polarized light. Additionally, amyloid deposits can be stained with Thioflavin T and S, which also exhibit fluorescence under ultraviolet light. However, amyloid deposits are resistant to staining with hematoxylin and eosin (H&E), which is a common staining technique used in histopathology.
**Why Each Wrong Option is Incorrect**
**Option A:** Congo Red - Incorrect, as amyloid deposits indeed stain positively with Congo Red.
**Option B:** Thioflavin T - Incorrect, as amyloid deposits also stain positively with Thioflavin T.
**Option C:** Hematoxylin and eosin (H&E) - Correct, as amyloid deposits do not stain positively with H&E.
**Option D:** Crystal violet - Incorrect, as amyloid deposits can also be stained with crystal violet.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that amyloidosis can present with a wide range of clinical symptoms, depending on the affected organ system. A high index of suspicion and a thorough diagnostic workup, including histopathological examination and immunohistochemical staining, are crucial for diagnosing amyloidosis.
**Correct Answer:** C. Hematoxylin and eosin (H&E).