MOLLUSCUM CONTAGIOSUM

DERMATOLOGY LECTURE NOTES

DEBABRATA BANDYOPADHYAY
PROFESSOR & HEAD, DEPT. OF DERMATOLOGY,
R. G. KAR MEDICAL COLLEGE, CALCUTTA, INDIA

Molluscum contagiosum (MC) is a common, self-limited, benign viral infection of the skin caused by a member of the pox-virus group. MC is transmitted by close personal contact including sexual contact. The condition typically involves young children. In adults, the infection occurs with increased frequency in presence of HIV infection. The lesions of MC have a distinct appearance of firm papules and nodules with central depressions.
 

ETIOLOGY & PATHOGENESIS

• MC is caused by molluscum contagiosum virus (MCV), which belongs to the pox-virus group of DNA viruses. It is one the largest known pathogenic viruses. There are more than one types of  MCV , MCV1 being the most common type of virus causing MC worldwide, particularly among the children, while MCV2 is the common type found in HIV infected individuals.

• Transmission occurs by close personal contact and often through fomites – towels, bath, and swimming pools.

• The virus replicates within the cytoplasm of infected epidermal cells, pathologic changes induced by the virus leads to formations of large hyaline acidophilic masses inside the cytoplasm ( known as molluscum bodies of Henderson-Paterson bodies). Localized hypertrophy of epidermis extends into the dermis without disrupting the basement membrane and also projects above the skin as a visible lesion. Secondary infection may lead to an inflammatory reaction.

• The incubation period is two to eight weeks.

CLINICAL FEATURES

• All races and both sexes are affected equally.

• Mc can occur at any age but it more commonly involves children younger than five years and sexually active young individuals.

• MC is mostly asymptomatic, but itching, tenderness and pain may occur in inflamed lesions.

• The primary lesions of mc are highly characteristic: individual lesions are firm, smooth, skin-colored, pinkish or pearly white papules and nodules with a central umbilication.

• Usually 2 to 6 mm in diameter, the lesions may be larger in some cases particularly in HIV-infected persons.

• Irritated and inflamed lesions may show crusting and may look like an abscess.

• The number of the papules may vary from 1 to 20 in an average case, but may be hundreds. They may be widely scattered or closely grouped.

• Confluence of multiple lesions may form a plaque.

• Compressing the lesion will cause the central core of a cheesy material to pop out.

• The common sites of affection are the face, trunk and limbs. Sexually transmitted cases may involve the genitalia, pubis, thighs and lower abdomen.

• Rare cases have affected the oral mucosa, lips,  eyelid and conjunctiva.

• Widespread lesions may occur in immunocompromised persons with HIV infection, lymphoma, leukemia, other malignancies, and immunosuppressive drug therapy.
  
  Complications:

• Secondary infections      

• Eczematization 

• Conjunctivitis/keratitis from eyelid infection

DIFFERENTIAL DIAGNOSIS

DIAGNOSIS

• Diagnosis is usually done on clinical grounds alone by the typical appearance of the lesions.

• Expression of materials stained with Giemsa, Wright or Gram stain reveals molluscum bodies.

• Biopsy, which shows characteristic features of epidermal hyperplasia with intracytoplasmic eosinophilic inclusion bodies in the keratinocytes, may be required in rare cases.

COURSE AND PROGNOSIS

• The prognosis is excellent and most cases are self-limited.

• Individual lesions may persist for months before resolving.

TREATMENT

• Liquid nitrogen cryotherapy

• Light electrodessication

• Removal with curettage, compression or needling followed by touching the base of the lesion with iodine.

• Cauterization with trichloroacetic acid, silver nitrate  phenol .or KOH

• Application of vesicant: cantharidin

• Prolonged application of tretinoin and 5-fluorouracil in resistant cases.

• Application of podophyllotoxin

• Topical imiquimod

• In HIV-infected persons: topical or IV cidofovir have given good results

• Systemic therapy: there are some reports of beneficial effects of prolonged systemic cimetidine and griseofulvin.

Prevention:

• Avoidance of skin-to-skin contact with infected persons

• Treatment of lesions prevents further spread and autoinoculation

• Chlorination of swimming pools.

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