Molluscum Contagiosum
A viral skin infection causing small, firm, pearly bumps with a dimple in the center, most common in children.
Emergency Management: None directly related to the virus itself, but secondary systemic infections from aggressive scratching could theoretically lead to cellulitis requiring IV antibiotics.
Molluscum contagiosum is a localized, self-limiting viral skin infection caused by the Molluscum contagiosum virus (MCV), a member of the Poxviridae family. It presents as firm, dome-shaped, umbilicated papules on the skin and is common in children, sexually active adults, and immunocompromised individuals.
Detailed Overview
The condition is highly contagious and spreads via direct skin-to-skin contact, fomites (such as towels or pool equipment), and autoinoculation. While the lesions are typically asymptomatic and resolve spontaneously over months to years in immunocompetent individuals, they can cause distress, pruritus, and cosmetic concern. In adults, presentation in the anogenital region is considered a sexually transmitted infection. Severe, widespread, or giant lesions should prompt investigation for underlying immunodeficiency, particularly HIV.
Epidemiology & Demographics
Highly prevalent worldwide, especially in warm, humid climates. Peak incidence occurs in children aged 1 to 10 years. An estimated 2-8% of children worldwide are affected. In adults, it is a common STI.
Etiological Mechanism
Caused by the Molluscum contagiosum virus (MCV), a DNA poxvirus. There are four major subtypes (MCV 1-4), with MCV-1 being the most common cause in children and MCV-2 more often associated with sexual transmission in adults.
Primary Causes
Direct skin-to-skin contact with an infected individual
Fomite transmission (sharing towels, clothing, sponges)
Sexual contact (in adults)
The MCV infects the epidermal cells, specifically the stratum basale, replicating in the cytoplasm (characteristic of poxviruses). As the virus replicates, the epidermal cells hypertrophy and proliferate, forming a lobulated mass. Large intracytoplasmic inclusion bodies (Henderson-Patterson bodies) form, which eventually push the host cell nucleus to the periphery. The resulting cellular destruction and accumulation of viral particles form the central umbilication and the characteristic cheesy core of the lesion.
Diagnostic Criteria & Guidelines
Diagnosis is overwhelmingly clinical, based on the characteristic appearance of firm, umbilicated papules. Dermoscopy can aid by showing a central polylobular white-to-yellow amorphous structure with peripheral crown vessels.
In immunocompetent children, benign neglect (observation) is often the first-line recommendation due to spontaneous resolution within 6-18 months. If treatment is desired to prevent spread or for cosmetic reasons, destructive therapies are used: Cryotherapy (liquid nitrogen applied for 3-5 seconds per lesion) or topical Cantharidin 0.7% (applied in-office, washed off in 4 hours).
Second-Line & Adjunctive Therapy
Topical retinoids (Tretinoin 0.025% cream applied once daily at night) or Imiquimod 5% cream (applied 3x weekly) can be considered, though efficacy is variable. Curettage is highly effective but painful and may leave scars. Recently FDA-approved Berdazimer 10.3% topical gel is an option for patients >1 year old.
Surgical & Procedural Management
Curettage or physical extraction of the central core can provide rapid resolution but requires local anesthesia (e.g., EMLA cream) and carries a risk of scarring.
Patient Counseling & Advice
Inform the patient/parents that the condition is benign and self-limiting, though it may take 1 to 2 years for all lesions to fully disappear. Explain the 'BOTE sign', where bumps get red and angry before they go away, and reassure them this is a normal immune response, not an infection.
Follow-Up & Monitoring Schedule
Re-evaluation in 4-6 weeks if undergoing active treatment (like cryotherapy) to treat newly emerged lesions due to the long incubation period.
Preventive Strategies
Strict personal hygiene. Condom use provides incomplete protection for genital molluscum as lesions may occur on uncovered areas like the lower abdomen and thighs.
Excellent for immunocompetent individuals with complete, scarless resolution typical. Severe and prolonged courses are seen in immunocompromised patients (e.g., HIV), requiring HAART to restore immune function for clearance.