All the following diseases are associated with peripheral blood eosinophilia except-
**Core Concept**
Peripheral blood eosinophilia refers to an elevated count of eosinophils in the peripheral blood, which can be a response to various conditions such as infections, allergic reactions, or parasitic infestations. Eosinophils play a crucial role in the body's defense mechanism, particularly against parasites and in allergic reactions.
**Why the Correct Answer is Right**
Peripheral blood eosinophilia is commonly seen in conditions like eosinophilic pneumonia, hypereosinophilic syndrome, and parasitic infestations such as toxocariasis or filariasis. In these conditions, eosinophils are activated and released into the bloodstream in response to the pathogen or allergen. The correct answer is associated with a condition where eosinophilia is not typically seen.
**Why Each Wrong Option is Incorrect**
**Option A:** Eosinophilic pneumonia is characterized by an infiltration of eosinophils into the lung tissue, leading to peripheral blood eosinophilia. Therefore, it is associated with peripheral blood eosinophilia.
**Option B:** Hypereosinophilic syndrome is a condition where there is an overproduction of eosinophils, leading to their accumulation in various tissues and organs, including the peripheral blood. Thus, it is associated with peripheral blood eosinophilia.
**Option C:** Toxocariasis is a parasitic infection caused by Toxocara species, which can lead to peripheral blood eosinophilia due to the body's immune response to the parasite.
**Clinical Pearl / High-Yield Fact**
When encountering a patient with peripheral blood eosinophilia, it is essential to consider the underlying cause, as it can range from benign conditions to life-threatening diseases.
**Correct Answer: D.**