Question

Four stages of formation of 'pox' lesion are grouped under each of the following. Choose correct sequence of formation of 'pox' lesion
(A) Vesicle
(B) Papule
(C) Pustule
(D) Pox
Choose the correct answer from the options given below:

• A. (A), (B), (C) and (D)
• B. (C), (A), (B), (D)
• C. (B), (A), (C), (D)
• D. (C), (B), (A), (D)

Hint:

Remember the progression of pox lesions using the acronym M-P-V-P-S:
Macule (flat red) \(\rightarrow\) Papule (raised solid) \(\rightarrow\) Vesicle (fluid blister) \(\rightarrow\) Pustule (pus blister) \(\rightarrow\) Scab/Pox (dry crust).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Poxviruses are cutaneous pathogens that replicate in the cytoplasm of epidermal cells.
They cause characteristic skin lesions that progress through a highly predictable sequence of gross and microscopic pathological stages.

Step 2: Detailed Explanation:
The pathogenesis of a poxvirus skin lesion begins after local inoculation and viral replication in the stratum spinosum of the epidermis.
The lesion progresses through the following sequential stages:
1. Macule (Initial stage - not listed): A flat, erythematous (red) spot on the skin caused by local vascular congestion.
2. Papule (B): Rapid viral replication causes epidermal cell hyperplasia and ballooning degeneration.
This results in a firm, raised, solid nodule on the skin surface.
3. Vesicle (A): The ballooned, degenerative epidermal cells rupture, and extracellular fluid accumulates within the epidermis.
This forms a clear, fluid-filled blister or vesicle.
4. Pustule (C): Neutrophils and other inflammatory leukocytes migrate into the vesicle in response to cell death and cytokines.
This turns the clear fluid cloudy and purulent, forming a pus-filled pustule.
5. Pox Scab (D): The pustule eventually ruptures or desiccates.
The necrotic debris, dried inflammatory exudate, and degenerated cells form a dry, dark crust or scab (often referred to as the "pox" or crust stage), which eventually sloughs off to leave a scar.
Therefore, the correct pathological sequence is Papule (B) \(\rightarrow\) Vesicle (A) \(\rightarrow\) Pustule (C) \(\rightarrow\) Pox/Scab (D).
This corresponds to sequence (B), (A), (C), (D).

Step 3: Final Answer:
The correct option is (C).