Molluscum Contagiosum Dimple Warts

CLINICAL APPLICATION QUESTIONS

A 16-year-old male high school student presents with a large number of papular lesions of recent onset in the right thoracic and axillary region. There is a second grouping of similar lesions on the right knee. The patient is on the wrestling team, desires removal of the lesions, and was sent to you by his wrestling coach to find out if they might be contagious. You suspect this is molluscum contagiosum.

1. What are the primary lesions you would expect to find in molluscum contagiosum?

2. What is the prognosis for molluscum contagiosum?

3. How do you answer the patient's question about whether this condition is contagious?

4. How do you confirm your diagnosis of molluscum contagiosum?

5. If this is molluscum contagiosum, how will you treat it?

APPLICATION GUIDELINES

Specific History

Onset

Molluscum warts occur characteristically in small children and in young adults, although they may be seen occasionally in any age group. They present as single or grouped papules, and parents will often indicate there was a single lesion present for some time. The incubation period after exposure has been estimated to vary from 14 days to 6 months. Molluscum contagiosum (MC) virus is a member of the poxvirus family and is not related to human papilloma virus, the cause of common verrucous warts.

Evolution of Disease Process

The infection usually starts with single or a small number of lesions and, if left untreated, will gradually spread to the point where hundreds of papules may develop. In small children, the face, neck, and upper trunk, especially the axillae and antecubital creases, are sites of predilection. Young adults more often present with lesions on the lower abdomen, pubic escutcheon, or inner thighs contracted during sexual transmission. The presence of MC lesions in the pubic area occurs from autoinoculation in small children and should not be considered a sign of sexual abuse unless there is other evidence. Molluscum warts are very common in human immunodeficiency virus (HIV) disease and occur typically on the face and beard areas.

In children, and occasionally in young adults, eczematous patches will develop within the regions of activity. The eczema is identical to patches of atopic dermatitis and, if left untreated, the resultant excoriations can lead to dissemination of the MC infection.

From: Current Clinical Practice: Dermatology Skills for Primary Care: An Illustrated Guide D.J. Trozak, D.J. Tennenhouse, and J.J. Russell © Humana Press, Totowa, NJ

Whether this represents an exacerbation of latent atopic disease or a delayed immune response to the virus is uncertain. Atopic dermatitis patients do seem to have an increased incidence of MC.

Although spontaneous remissions occur, untreated MC can last for years. During this time, the victim remains a potential source of infection to others.

Evolution of Skin Lesions

Although single lesions occur, most often these warts appear in groups and localize within the presenting anatomic area. On the trunk they are usually unilateral; on the pubic areas and inner thighs, involvement is usually on both sides. Parents or patients will often point to lesions that have involuted or are inflamed and involuting. Involution occurs even as new lesions continue to form. Solitary MC papules may exceed 1 cm in size. In acquired immunodeficiency syndrome (AIDS) and certain other states of immunosup-pression, the lesions may be unusually profuse and large or may be atypical and simulate other infectious or malignant conditions.

Provoking Factors

Molluscum warts are spread by close physical contact and by fomites. The physical nature of play among preschool children predisposes them, and outbreaks often occur within family and day-school classroom units. In school-aged children, common swimming pool facilities, communal shower facilities, and contact sports have been implicated. Sexual contact is the most common mode of transmission in young adults.

Immunosuppression predisposes patients to MC, which is the most likely reason for the increased frequency in atopics and in HIV victims and accounts for their unusual virulence in patients with HIV, sarcoid, and leukemia, and patients on chemotherapy. Multiple, atypical, or therapeutically resistant MC are a sign of HIV infection and correlate with disease progression.

Self-Medication

Self-treatment is not a problem in MC.

Supplemental Review From General History

The presence of widespread, large, or atypical MC lesions should prompt a general review searching for systemic diseases such as HIV infection, sarcoid, or underlying malignancy.

Dermatologic Physical Exam

Primary Lesions

1. Dome-shaped umbilicated papules (see Photo 1).

2. Dome-shaped umbilicated nodules (rare).

3. Plaques of tightly grouped papules (rare).

Pinhead-sized dome-shaped firm flesh-colored papules gradually enlarge to reveal a central dimple or umbilication. As the wart matures, a thin ridge or scale may be seen at the edge of the pit (see Photo 2). More mature lesions may become yellow or pink in color, and lesions that are ready to involute are usually a deep dusky red (see Photo 3). Solitary mature lesions may, on rare occasions, exceed 1 cm in diameter.

Secondary Lesions

1. Crust formation on involuting lesions.

2. Excoriations of some papules.

3. Mild scarring.

As lesions evolve, some will enlarge rapidly, become edematous and dusky red, and form a yellow or dark crust. In patients with associated eczema, excoriations are usually present and may cause mild scarring, as can overly exuberant treatment. Solitary large lesions are rare and may simulate a keratoacanthoma, squamous cell carcinoma, or basal cell carcinoma. These are more common in HIV disease. In HIV-positive patients, lesions of disseminated cryptococcosis, histoplasmosis, or cutaneous coccidioidomycosis can resemble MC lesions, but develop central necrosis as they enlarge.

Distribution

Microdistribution: None. Macrodistribution:

1. Face, neck, upper trunk, axillary, cubital, and genital regions in small children (see Fig. 1).

2. Lower abdomen, pubic escutcheon, and inner thighs in young adults (see Fig. 2).

3. Face and beard area with HIV disease (see Fig. 3).

Configuration

1. Grouped, usually within the region of onset (see Photos 1,2,4).

2. Occasionally linear following inoculation by excoriation (autoinoculation).

Indicated Supporting Diagnostic Data

Typical MC is clinically diagnostic. No supporting data are indicated. Atypical lesions (large or necrotic) and lesions that are unusually refractory to therapy or are seen in the context of HIV disease need laboratory confirmation.

1. Molluscum smear: This simple test can be performed by gently squeezing or curetting a lesion and examining the central contents. The unstained contents of MC will show anucleate homogeneous ovoid molluscum bodies, which are diagnostic (see Photo 5).

2. Skin biopsy: MC has very characteristic histology. When the clinical findings are confusing and a smear is negative, a biopsy is diagnostic.

Therapy

Avoidance

Patients should avoid sources of reinfection if these can be identified from the history. They also should avoid communal swimming pools, baths, and use of fomites such as common towels and shared clothing items.

Moluscum Contagiosum After Cryotherapy

Cryotherapy

Light freezing with liquid nitrogen (LN2) is effective and nonscarring. This is most effective in adult cases and must be repeated every 10 to 14 days until clear. The authors strongly recommend use of a cotton swab rather than cryospray application. These lesions require only a short blanch to accomplish destruction. With cryospray it is very easy to cause permanent scars, especially on the facial skin. Small children will usually not tolerate the discomfort of LN2.

Vesicants

Treatment of small children is best accomplished by applications of 0.7% cantharidin in a film-forming adhesive base. The applications are done very carefully to the tops of visible lesions every 14 days until clear. The wooden applicator is not threatening, the

Molluscum Contagiosum Pubic Zone
Figure 2: Macrodistribution of molluscum contagiosum in young adults.

applications are painless, and long-term there is minimal risk of scarring. The application is left in place until the evening bath. Occlusion is not required.

Irritants

An alternative but somewhat less effective method is the application of an aqueous solution containing 2% iodine and 2.4% sodium iodide. The solution is applied with a flat toothpick and is gently introduced into the central pore or dimple. This solution is available without prescription; however, because of potential toxicity with an accidental ingestion, application in the practitioner's office is strongly recommended.

Curettage

Curettage with or without fulguration has been used, but is tedious with a large number of lesions and can lead to unacceptable scarring. Today this technique is mainly used to obtain tissue for histology when the diagnosis is uncertain.

Warts Pubic Area
Figure 3: Macrodistribution of molluscum contagiosum in HIV disease.

Conditions That May Simulate Molluscum Contagiosum

Basal Cell/Squamous Cell Carcinomas, Keratoacanthoma

Solitary MC lesions can simulate any of these nodular lesions. All three tend to arise on heavily sun-damaged skin, but each may have a central dell or keratotic pit. A mollus-cum smear or a biopsy will differentiate them.

Cryptococcosis and Other Deep Fungi

Cutaneous lesions of cryptococcosis and other deep fungi can occasionally simulate giant molluscum lesions. Both conditions favor the facial skin and occur in advanced HIV disease and other states of profound immunologic suppression. With cryptococcal lesions the central core has a more gelatinous quality and saline exam shows large budding yeast cells rather than molluscum bodies. India ink examination will demonstrate the characteristic clear capsule. Histoplasmosis and coccidioidomycosis can also produce similar lesions. Biopsy with stains for fungi are indicated if routine histology fails to show typical molluscum bodies. Cutaneous cryptococcosis, histoplasmosis, and coccidioidomycosis are all a sign of disseminated systemic infection.

ANSWERS TO CLINICAL APPLICATION QUESTIONS

History Review

A 16-year-old male high school student presents with a large number of papular lesions of recent onset in the right thoracic and axillary region. There is a second grouping of similar lesions on the right knee. The patient is on the wrestling team, desires removal of the lesions, and was sent to you by his wrestling coach to find out if they might be contagious. You suspect this is molluscum contagiosum.

1. What are the primary lesions you would expect to find in molluscum contagiosum?

Answer: Grouped dome-shaped umbilicated papules; less commonly, umbilicated nodules.

2. What is the prognosis for molluscum contagiosum?

Answer: Although spontaneous involution can occur, it is more common for the lesions to multiply and spread unless treated.

3. How do you answer the patient's question about whether this condition is contagious?

Answer: Molluscum warts are highly contagious by both direct contact and fomite transmission. This patient should not be wrestling until the lesions are completely resolved, and the coach should be warned to clean mats and other equipment with which the wrestlers come in contact.

4. How do you confirm your diagnosis of molluscum contagiosum?

Answer: Express the contents from the center of a papule. Perform a molluscum smear.

5. If this is molluscum, how will you treat it?

Answer: Cryotherapy or vesicant application is appropriate. There are some studies that show that topical Imiquimod may also be effective.

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