Makindo Medical Notes

Related Subjects: |Nikolsky's sign |Koebner phenomenon |Erythema Multiforme |Pyoderma gangrenosum |Erythema Nodosum |Dermatitis Herpetiformis |Lichen Planus |Acanthosis Nigricans |Acne Rosacea |Acne Vulgaris |Alopecia |Vitiligo |Urticaria |Basal Cell Carcinoma |Malignant Melanoma |Squamous Cell Carcinoma |Mycosis Fungoides (Sezary Syndrome) |Xeroderma pigmentosum |Bullous Pemphigoid |Pemphigus Vulgaris |Seborrheic Dermatitis |Pityriasis/Tinea versicolor infections |Pityriasis rosea |Scabies |Dermatomyositis |Toxic Epidermal Necrolysis |Stevens-Johnson Syndrome |Atopic Eczema/Atopic Dermatitis |Psoriasis

🦠 Molluscum contagiosum is a common, highly contagious viral skin infection caused by a DNA poxvirus. 👶 Most often affects children & young adults, presenting with small, pearly papules with central umbilication. ✅ Harmless & self-limiting, but widespread/persistent cases may need treatment.

📖 About

• Definition: Viral infection with pearly papules + central dimple.
• Etiology: Caused by molluscum contagiosum virus (MCV), a member of the Poxviridae family.
• Epidemiology: Common in children, immunocompromised patients, and sexually active adults.
• Transmission: Direct contact, fomites (towels, clothes), and sexual contact in adults.

📌 Lesions are most often seen on the trunk, limbs, and in adults → genital area.

🩺 Clinical Features

• ✨ Lesion: Small, pearly papule with central umbilication.
• 📏 Size: 2–6 mm, may enlarge to 10–20 mm.
• 📍 Distribution: Trunk, limbs, face (children), genitalia (adults).
• ➰ Koebner phenomenon: Lesions may appear at trauma sites.
• 😣 Mild–moderate pruritus (↑ with atopic dermatitis).
• 🧾 No systemic symptoms; widespread lesions in adults → consider HIV testing.
• 🧴 Associated with atopic eczema → more extensive disease.

👁️ Clinical Signs

🔎 Investigations

• 🧑‍⚕️ Clinical diagnosis usually sufficient.
• 🔬 Skin biopsy if atypical (to rule out psoriasis/eczema).
• 🧫 KOH test if fungal infection suspected.
• 🧪 HIV test in adults with widespread disease.

🧾 Differential Diagnosis

• 🍄 Tinea corporis (ringworm) – scaly, ring-shaped, no umbilication.
• 🧪 Secondary syphilis – serological confirmation needed.
• 🌿 Eczema (Atopic dermatitis) – itchy, scaly, often chronic.
• ⭕ Granuloma annulare – ring-shaped, no umbilication.

💊 Management

• ⏳ Observation: Usually resolves spontaneously in 6–18 months.
• 😌 Symptomatic:
  • Antihistamines for itch (loratadine, diphenhydramine).
  • Topical steroids (e.g., hydrocortisone) + emollients for eczema/itch.
• ⚡ Local treatments:
  • Cryotherapy (liquid nitrogen).
  • Curettage (scraping lesions).
  • Imiquimod (off-label, limited effect).
  • Ophthalmology referral if eyelid lesions.
• 🌐 Systemic:
  • HAART in HIV-positive patients often clears lesions.
• 🛡️ Prevention:
  • Avoid sharing towels/clothing.
  • Maintain good hygiene.
  • Children do not need exclusion from school/swimming.

📉 Prognosis

• ✅ Self-limiting → clears in 6–18 months.
• 🙌 Complete recovery without scarring in most.
• 🎨 Post-inflammatory hyper/hypopigmentation possible (esp. in darker skin).
• 🔁 Recurrence rare (<3%).

📌 Conclusion

Molluscum contagiosum is a benign, self-limiting poxvirus infection. Treatment is not always necessary, but options exist to expedite clearance or reduce symptoms, especially in immunocompromised patients.

📚 References

• Harmon AJ, Gupta AK. Pityriasis rosea: An update. Dermatology, 2004; 208(2):145–152.
• Mayo Clinic. Molluscum Contagiosum. Link
• NIH. Molluscum Contagiosum. Link
• WHO. Skin Conditions. Link
• AAD. Molluscum Contagiosum Overview. Link