Molluscum contagiosum

Molluscum contagiosum
Diagnosis in short
Molluscum contagiosum. H&E stain.
LM	large suprabasilar epidermal cells with (granular) eosinophilic cytoplasmic inclusions that usually fill the cytoplasm; small peripheral nucleus
Gross	dome-shaped papules, flesh coloured or pearly
Site	skin, usu. face or trunk
Prognosis	benign

Molluscum contagiosum, abbreviated MC, is an infectious skin disease that is occasionally seen by pathologists. It very distinctive and, thus, an exam favourite.

General

• Etiology: caused by molluscum contagiosum virus.
• May be abundant in immune deficient individuals, e.g. HIV/AIDS.

Gross

Features:

• Dome-shaped papules, flesh coloured or pearly.
• Usually face or trunk.
• +/-Central umbilication.
  • Central depression.

DDx - gross:

• Skin tag.

Image

• 

  Molluscum contagiosum - clinical. (WC)

Microscopic

Features:

• A suprabasilar epidermal lesion consisting of "molluscum bodies" -- in other words "molluscum bodies" are found above the stratum basale +/- extension to the skin surface.
  • Molluscum bodies - key feature:
    • Large cells with (granular) eosinophilic cytoplasmic inclusions.
      • The inclusions usually fill the cytoplasm.
      • Inclusions are usually one per cell... but may be multiple.
    • Small peripheral nucleus.
• +/-Lymphocytes.

Notes:

• Molluscum bodies very vaguely resemble signet ring cells -- but:
  • Cytoplasm is eosinophilic and granular.
  • Nucleus usually smaller than in signet ring cells.
  • Molluscum bodies are only in the epidermis - an uncommon place to find SRCs without finding them elsewhere.
• The granular eosinophilic cytoplasmic inclusions represents accumulated virons.
• Molluscum bodies "grow" toward the surface

DDx:

• Nothing really - it is very distinctive.

Images

• 

  Molluscum contagiosum - high mag. (WC)

• 

  Molluscum contagiosum - low mag. (WC)

• 

  Molluscum contagiosum. (WC)

• 

  Small molluscum contagiosum. (WC)

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SKIN LESION ("SKIN TAG"), EXCISION:
- MOLLUSCUM CONTAGIOSUM.

Micro

The section shows fragments of skin with epithelium on three sides. Large suprabasilar cells with eosinophilic intracytoplasmic inclusions (molluscum bodies) and small eccentric nuclei are present, and extend to the skin surface. The epithelium is acanthotic; however, it matures to the surface. There is no significant inflammation.

See also

• Non-malignant skin disease.