• 5 year old male child presented with complaints of raised skin lesions over the face and trunk for the past 2 months.
  • No H/o itching,pain,discharge or family H/o.

O/E

  • Multiple discrete small non tender waxy, pearly white dome shaped papules of size varying from 2-5 mm noted over the chin,left shoulder and trunk.
  • Koebnerization present.
  • Palms and soles normal.
  • Oral and genital mucosa normal.
  • Hairs and nails normal
Diagnosis: Molluscum contagiosum (MC)

DISCUSSION

Organism
  • MC caused by Molluscum contagiosum virus is a common benign cutaneous viral infection specific to humans
  • MC virus Types 
  • MCV-1~76-97% infections
  • MCV-2 in adults and immunocompromised
  • MCV-3 and MCV-4~ rare
Incubation period :2 to 6 weeks

Age:

  • most common – 2 to 5 years
  • Young adults- sexually transmitted

Transmission:

  • Direct Skin or mucous membranes contact with infected persons or contaminated objects
  • sexual transmission
  • vertical transmission from mother to neonate rarely
  • autoinoculation and koebnerization

Predisposing factors:

  • athletes participating in contact sports
  • usage of swimming pools,bath towels, shared bathing facilities
  • atopic eczema
  • Immunocompromised patients- HIV(<200cells/microliter), hematological malignancy, sarcoidosis, idiopathic CD4 lymphocytopenia, DOCK-8 deficiency,
  • immunosuppressive therapy

Clinical feature:

  • Small pink pearly or skin coloured papules that enlarge to form flat topped, dome shaped, waxy opalescent, umbilicated papules 
  • whitish curd like substance containing virus expressed on pressure
  • cluster arrangement 
  • linear arrangement due to koebnerization
  • More severe, extensive refractory and giant (>2.5 cm) cutaneous lesions and oral lesions in the absence of cutaneous lesions when immunocompromised

Pathology

  • MCV replicates in the cytoplasm of epithelial cell
  • Viral inclusion bodies-HENDERSON PATERSON BODIES) develop in basal layer and enlarge as cells rise through the epidermis
  • Proliferation and enlargement of Virion packed cell causes disintegration of stratum Corneum
  • formation of dimple like ostium through which the virions are released when inclusion bodies are ruptured

Impedes immune mechanism because of multiple genes

  • homolog of MHC class 1 heavy chain -antigen presentation inhibition 
  • Chemokine homolog -chemotaxis inhibition
  • Protein that prevents activation of death effector domain of cascade 8 -apoptosis inhibition
  • Glutathione homolog – apoptosis prevention in  UV and hydrogen peroxide damaged cells

Complications

  • secondary bacterial infection
  • Ulceration
  • Molluscum dermatitis
  • Gianotti crosti syndrome

Investigation:

  • Dermoscopy – central poly lobular white yellow amorphous structure surrounded by peripheral crown of blood vessels (RED CORONA)
  • Microscopy: when the extruded whitish material is crushed and stained with giemsa reveals Intracytoplasmic HP bodies

HPE:

  • Hypertrophied and hyperplastic epidermis
  • Inclusion bodies appear eosinophilic at lower cells of stratum Malpighi 
  • MC Bodies increase in size on moving towards surface displacing and compressing the nucleus 
  • Turns basophilic at granular and horny cell layers
  • Ultimately stratum corneum disintegrates releasing MC bodies.
  • Dermis little or no inflammatory infiltrate

DD:

  • Plane wart
  • Milia
  • Papular Granuloma annulare
  • Cryptococcosis 
  • Histoplasmosis IPO

Treatment:

General measures
  • Antihistamines when necessary to avoid scratching and autoinoculation 
  • Cover with bandage in case of contact sports or sharing equipment
  • Avoid swimming unless covered by a watertight bandage
Physically destructive procedures: (triggers immune response on rupturing the lesions)
  • Curettage
  • Co2 laser
  • Pulsed dye laser
  • Electrodesiccation
  • Cryotherapy at 3-4 weeks interval

Chemical destruction

  • KOH 5 to 10%
  • Silver nitrate
  • Trichloroacetic acid
  • Salicylic acid 12%
  • Phenol 
  • Cantharicidin0.7% in collodion base
  • Podophyllotoxin 0.5%

Immunomodulatory therapies

  • Intralesional interferon alpha or beta
  • Intralesional candida antigen injection
  • Cimetidine 
  • Imiquimod 5% in genital MC

Antiviral:

  • Cidofovir topical 1 to 3% cream or Iv
  • Avoid imiquimod and podophyllotoxin in pregnancy and breast feeding 
  • ART in HIV infected as MC clears when  CD4 count rises
  • Medium strength topical steroid to treat molluscum dermatitis and Gianotti crosti like reaction.
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