Persistent Molluscum Contagiosum

Vol. 10 •Issue 5 • Page 79
Persistent Molluscum Contagiosum

Case Study in a 6-Year-old Girl with Asthma and Eczema

Molluscum contagiosum is a common, noncancerous skin growth caused by a poxvirus.1-4 This highly contagious virus attacks skin and mucous membranes and is spread by direct skin-to-skin contact or through fomites.1-5 The lesions are autoinoculable and contagious to others.5 Molluscum contagiosum may be spread in swimming pools and has been reported among athletes participating in close contact sports such as wrestling.3-5 An increased incidence has been reported in atopic and immunocompromised patients, as well as patients who take corticosteroids or have a malignant disease.4-6 The estimated incubation period is 2 to 6 weeks.5 Spontaneous involution of molluscum contagiosum may occur in 2 to 4 years, but without treatment, infection may become persistent, pose a cosmetic concern, or cause associated symptoms such as a surrounding eczema, inflammation or hair follicle involvement and abscess formation.5 The affected person is contagious as long as lesions are present.2

Clinical Presentation

In the patient with molluscum contagiosum, physical examination reveals firm, pink to flesh-colored, domed, umbilicated papules that range in size from 1 mm to 15 mm.1,2,5 Caseous material may fill the dimple’s core.1 In children, lesions appear on the face, axillae, trunk and extremities.2 Other areas of involvement may include the popliteal fossae, groin, inner thighs, perianal areas, face, eyelids, mouth and, rarely, the conjunctiva and cornea.1,4,5 Diagnosis is made clinically or by skin biopsy.1 The possibility of sexual abuse should be explored in children with genitally grouped lesions.2,5 A child with hundreds of lesions should be evaluated for HIV and AIDS.2

Differential Diagnosis

Differential diagnoses include: warts, folliculitis, small epidermal cysts, closed comedones, condyloma acuminata, basal cell carcinoma and varicella.1,2


Treatment of molluscum contagiosum is optional. Since children may be traumatized by painful treatments, benign neglect (doing nothing) may be the appropriate approach in those who are not immunocompromised.4,5 The persistent nature of molluscum contagiosum, its cosmetic effects and its associated symptoms often make treatment the more attractive choice, however.4 Therapeutic options are primarily destructive measures.

Topical Agents

One therapeutic option for the destruction of molluscum is cryotherapy. Liquid nitrogen applied for 3 to 5 seconds may be used.1 Trichloroacetic acid 25% can be applied by dropper to the center of the lesion, followed by alcohol.2 Alternatively, tretinoin cream (Retin-A) can be applied to the lesion daily or nightly.1,2 These treatments may cause redness, swelling, peeling or discomfort for the patient.

Topical 5% imiquimod (Aldara) for the treatment of molluscum contagiosum (applied once daily for 5 days per week and left in place for overnight) has been investigated and holds promise as an effective treatment for difficult-to-treat cases.6 Side effects include changes in skin color, burning, itching, redness, peeling and swelling.7

Imiquimod is an immune response modifier that is usually used to treat external genital and perianal warts.7 In a recent study, self-administered topical 5% imiquimod was used once daily for 5 days per week and left in place overnight in 15 patients with molluscum contagiosum. Eight molluscum patients (53%) achieved total clearance, and four (27%) achieved a >50% reduction in lesion size. Among these patients, seven were children (<16 years). Six of the seven children experienced complete regression. The most common adverse event reported by 31% of the patients was erythema.6

Application of cantharidin, a blistering extract from the blister beetle cantharis vesicatoris, can be effective.4 Cantharidin is applied sparingly to each lesion using the blunt end of a wooden cotton-tipped applicator. Avoid contact with healthy surrounding tissue.4 Parents should rinse treated areas with copious amounts of water after 4 to 6 hours–sooner if the child complains of burning or discomfort or if vesiculation is observed.4 Cantharidin treatment may result in significant local irritation with blister formation several hours later.5

A recent retrospective study of 300 children with molluscum contagiosum evaluated the safety, efficacy and parental satisfaction of cantharidin therapy. A known history of atopic dermatitis was reported in 41% (124) patients. The average number of treatment visits was 2.1. Most patients experienced blistering at application sites (92%). Other reported symptoms included erythema lasting up to 3 weeks (37%), mild to moderate pain (14%), transient burning sensation (10%), pruritis (6%), and post-inflammatory hypo- or hyperpigmentation (8%). Results showed that 90% of the patients experienced clearing and 8% reported significant improvement with cantharidin therapy. Only 2% reported the treatment to be completely ineffective. When interviewed, 95% of the parents stated they would treat with cantharidin again.4


Curettage with a sharp blade to remove the papule is another treatment option.2 Although this method is relatively painless and easy to perform, pretreatment with a topical anesthetic can obviate any discomfort.5

Oral Medication

At least one study has investigated the use of oral cimetidine (Tagamet), a histamine2-receptor antagonist, for the treatment of molluscum contagiosum.8 In the study, 13 subjects took cimetidine 40 mg/kg/day in tablet or liquid form, in divided doses of two or three times per day.8 Conventional treatment modalities had been unsuccessful or difficult to apply in all subjects. Common reasons were inability of children to cooperate with cantharidin application; fear of pain with cryotherapy or curettage; facial and periorbital lesions; extensive lesions; parental dissatisfaction with repeated blistering; and inconvenience of repeated clinic visits for application of cantharidin. A history of atopy was identified in 10 of the 13 patients. Treatment consisted of a 2-month course of oral cimetidine (40 mg/kg/day) in two to three divided doses. Of the 12 patients who completed the 2-month treatment period, nine had clearance of all molluscum and one had partial clearance with no new lesions.8 There were no complaints of untoward side effects. Cimetidine does not currently have an approved indication for this use.

Case Presentation

“Katie” is a 6-year-old, well-developed, well-nourished (23 kg) Caucasian girl who initially presented with multiple small, shiny, firm, flesh-colored dome-shaped lesions on her thighs. One area on her right thigh contained an erythematous, papular, irritated, scaly, irregular-shaped lesion that itches and burns. These lesions surfaced several weeks previous. Her mother had been applying topical 0.5% hydrocortisone cream, which has not resulted in improvement. The lesions are aggravated by heat and sweat. The mother reported that Katie swims daily at the public pool and uses sunscreen.

The child has a history of asthma, allergies and atopic dermatitis (eczema) since infancy. Current medications include: albuterol inhalation aerosol two puffs q.i.d. as needed; fluticasone propionate (Flovent) inhalation aerosol (44 mcg) two puffs b.i.d.; montelukast sodium (Singulair) 5 mg chewable tablet q.d.; fluticasone propionate (Flonase) nasal spray (50 mcg) one spray to each nostril daily as needed; and loratadine (Claritin) syrup 1 tsp q.d. The child had attended camp 2 weeks earlier, during which she had an exacerbation of her asthma. The girl’s provider had prescribed a 5-day course of prednisolone syrup (15 mg/5mL) 1 tsp b.i.d., plus use of nebulized premixed albuterol sulfate inhalation solution (0.083%) 2.5 mg/3mL as needed.


The physical exam findings confirmed a diagnosis of molluscum contagiosum with surrounding eczematous reaction. Dermatologic diagnosis requires physical inspection and a thorough medical history. When the cause of a dermatologic problem is unknown, empiric treatment is often the best course.7 In this case, Katie’s mother had been applying 0.5% hydrocortisone cream with no improvement. Hydrocortisone is used for the management of inflammatory and allergic conditions, so the lack of therapeutic response ruled out the diagnosis of a minor skin irritation, eczema, contact dermatitis or insect bites. Diagnosis of molluscum contagiosum was based on the characteristics of the lesions, their distribution and physical appearance—small, shiny, firm, flesh-colored, dome-shaped lesions on the thighs. Surrounding eczema was diagnosed based on the child’s history and physical appearance—erythematous, papular, irritated, scaly, irregular-shaped lesions that itch.

Warts (verruca) appear as well-circumscribed, gray or brown, firm, elevated papules with a rough texture.1,9 Katie’s lesions did not meet this physical description. Folliculitis is an infection of the hair follicle appearing as erythematous papules and pustules on any hair-bearing surface.1,9 Katie’s lesions did not involve hair follicles. Closed comedones (blackheads) commonly affect the face, back and ears. They consist of discolored dried sebum that plugs an excretory duct of the skin and primarily occur during adolescence.1,9 Katie’s lesions were on the thighs and did not meet this criteria. Condyloma acuminata was ruled out because although these lesions are flesh-toned papules, this wart-like growth of the skin usually occurs on the external genitalia or near the anus.1 Basal cell carcinoma was ruled out because it is usually a singular lesion with telangiectasias.1 With varicella, skin lesions first appear on the back and chest, then spread to the face and proximal extremities, passing through stages of macules, papules, vesicles and crusts.1,9 Katie’s lesions had essentially remained unchanged since their first appearance, and had been present for several weeks.


Katie’s provider prescribed tretinoin micro 0.1% gel to be applied locally to the affected areas once daily for 7 to 10 days. She returned to the clinic 2 weeks later, and the lesions were still present. Minimal (if any) improvement had occurred. Some new lesions had also appeared on the antecubital areas of the arms, the tops of her feet, and her fingers. Cryotherapy with liquid nitrogen was used on four of the larger lesions (she could not tolerate treatment on any more lesions due to fear and pain). Tretinoin micro 0.1% gel was to be continued on the remaining lesions. Katie returned 2 weeks later and two of the four lesions treated with cryotherapy had resolved. The lesions being treated with tretinoin remained. Some of the lesions had developed inflammatory dermatitis (erythematous and swollen, with considerable discomfort). The provider referred Katie to a dermatologist.

The dermatologist examined Katie several weeks later. By that time, many lesions were present on her inner thighs, genital area, buttocks, legs, feet and hands. “I’m the ugliest girl in the world,” she cried. The physician prescribed cantharidin therapy for the molluscum contagiosum and local application of mometasone furoate cream 0.1% (Elocon) for the skin with inflammatory dermatitis following cantharidin treatment, and for the skin lesions with eczema.

Katie was treated five times at 3-week intervals with cantharidin. Following treatment with cantharidin, she experienced marked erythema, pruritis and burning that lasted 24 to 72 hours. Most of the treated molluscum formed 5 mm to 10 mm blisters that later burst spontaneously. Although some of the molluscum did not return after cantharidin therapy, other new crops appeared. After three cantharidin treatments, the dermatologist added other medications to the treatment regimen to be used between office visits. The physician prescribed imiquimod 5% cream 3 days per week (Monday, Wednesday, Friday) in a thin layer before bedtime, then removed with mild soap and water in the morning.10 Katie experienced no adverse reactions from the imiquimod, but the therapy was discontinued after 3 weeks due to lack of therapeutic effect.

Next, the dermatologist prescribed tazarotene topical gel 0.05% (Tazorac), to be applied once daily between cantharidin treatments. No adverse reactions were reported, but this medication was discontinued after 3 weeks due to lack of therapeutic effect. Her mother purchased a multiherbal dietary supplement marketed as “Infection Fighter” (containing Echinacea, St. John’s wort, yerba mansa root, red root, chamomile, spilanthes, garlic bulb, Oregon grape root, usnea whole lichen, and rosemary ariel). Katie took 1.0 mL daily for 2 weeks. No adverse reactions occurred. This, too, was discontinued due to lack of therapeutic effect. After the fifth treatment with cantharidin, the dermatologist prescribed cimetidine 200 mg tablets once daily at bedtime for 14 days. No adverse reactions were reported. Total clearance of molluscum contagiosum occurred within 14 days, and no new lesions developed.

After 11 months of persistent molluscum contagiosum, the “ugliest girl in the world” vanished. A happy, confident, now 7-year-old girl can once again feel beautiful and confident in a swimsuit.


The total clearance of molluscum contagiosum using oral cimetidine in a dose of less than 10 mg/kg/day in this case study is encouraging. The possibility of spontaneous resolution cannot be completely ruled out, but in this case seems unlikely. Further controlled studies to establish the efficacy of cimetidine in the treatment of molluscum contagiosum are needed.


1. Hooper BJ, Goldman MP, eds. Primary Dermatologic Care. St. Louis: Mosby; 1999:253-254.

2. Burns CE, Barber N, Brady MA, Dunn AM, eds. Pediatric Primary Care: A Handbook for Nurse Practitioners. Philadelphia: W.B. Saunders and Company;1996: 750.

3. American Academy of Dermatology. Molluscum Contagiosum. Schaumburg, Ill: American Academy of Dermatology; 2000.

4. Silverberg NB, Sidbury R, Mancini AJ. Childhood molluscum contagiosum: experience with cantharidin therapy in 300 patients. J Am Acad Dermatol. 2000;43(3):503-507.

5. Ordoukhanian E, Lane AT. Warts and molluscum contagiosum: beware of treatments worse than the disease. Postgraduate Medicine. 1997;101(2): 223-235.

6. Hengge UR, Esser S, Schultewolter T, Behrendt C, Meyer T, Stockfleth E, Goos M. Self-administered topical 5% imiquimod for the treatment of common warts and molluscum contagiosum. British Journal of Dermatology. 2000;143:1026-1031.

7. McKenry LM, Salerno E. Mosby’s Pharmacology in Nursing. 18th ed. St. Louis: Mosby; 1992: 1019-1041.

8. Dohil M, Prediville JS. Treatment of molluscum contagiosum with oral cimetidine: clinical experience in 13 patients. Pediatric Dermatology. 1996;13(4):310-312.

9. Wong D. Whaley & Wong’s Nursing Care of Infants and Children. 6th ed. St. Louis: Mosby; 1999: 720-776.

10. 3M Pharmaceuticals. Aldara Cream 5% (imiquimod): New Hope for Patients with External Genital Warts: Summary of Patient Information. St. Paul, Minn.: 3M Pharmaceuticals; 1999.

Amy Zlomek Hedden is a nurse practitioner at Bakersfield Family Medical Center in Bakersfield, Calif. She is also a nursing instructor and pediatric content expert at California State University in Bakersfield and provides pediatric consultation services to various hospitals, home health agencies and health departments in her area. She has a master’s degree.

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