POX VIRUS – MOLLUSCUM CONTAGIOSUM

POX VIRUS – MOLLUSCUM CONTAGIOSUM

Definition

• Molluscum contagiosum (MC) is a viral infection caused by a type of poxvirus.
• It is a chronic, benign, and contagious skin infection.

Causes

• MC is caused by the Molluscum contagiosum virus (MCV).
• It is transmitted through direct skin-to-skin contact, contaminated towels, or clothing.
• The virus infects the skin and causes a localized skin lesion.

Types

• MC can occur in different forms, including: → Common or classical MC → Flat MC → Atypical or inflammatory MC

Pathogenesis

• The MC virus infects the skin cells (keratinocytes) through direct contact.
• The virus then multiplies within the skin cells, causing them to become distorted and form a papule.
• The papule eventually develops into a characteristic MC lesion.
• The virus is shed into the environment through skin lesions, allowing it to spread to other people.

Step-by-Step Pathogenesis:

1. → The MC virus attaches to the skin cells (keratinocytes).
2. → The virus penetrates the skin cells and enters the nucleus.
3. → The virus multiplies within the skin cells, causing them to become distorted.
4. → The distorted skin cells form a papule, which eventually develops into a characteristic MC lesion.
5. → The virus is shed into the environment through skin lesions.

Morphology

• MC lesions are typically: → Papular or nodular → Round or oval in shape → 2-10 mm in diameter → Fleshy or flesh-colored → Surrounded by a small white or pink halo

Clinical Features

• MC lesions typically appear on the skin, including: → Face → Neck → Arms → Legs → Trunk
• They can occur anywhere on the body.
• MC lesions are usually asymptomatic, but may be itchy or tender.

Complications

• MC can cause: → Secondary bacterial infection (e.g., impetigo) → Scarring (if lesions are scratched or squeezed) → Skin discoloration (if lesions are scratched or squeezed)

Diagnosis

• MC is typically diagnosed based on: → Clinical presentation (appearance of lesions) → Physical examination → Biopsy (rarely needed)

Management

• MC is usually treated with: → Topical treatments (e.g., creams, ointments) → Punch biopsy (for diagnostic purposes) → Excision (for cosmetic purposes) → Antiviral medication (rarely needed)

Life Cycle

• The MC virus has a complex life cycle, but the key steps include:
  1. → Attachment: The MC virus attaches to the skin cells (keratinocytes).
  2. → Penetration: The virus penetrates the skin cells and enters the nucleus.
  3. → Replication: The virus multiplies within the skin cells.
  4. → Shedding: The virus is shed into the environment through skin lesions.
  5. → Transmission: The virus is transmitted to other people through direct skin-to-skin contact.

Memory Trick: "A.P.P.L.E." to remember the life cycle: → A: Attachment → P: Penetration → P: Replication → L: Shedding → E: Transmission