Molluscum contagiosum, also sometimes referred to as water warts, presents with harmless, smooth, waxy bumps that can mimic other skin conditions. Let’s explore more about this viral skin infection to better understand its presenting symptoms, developmental stages, and causes.
Table of Contents
What is it?
Molluscum contagiosum is a viral skin infection characterized by small, round, and usually painless bumps. These bumps or lesions are most commonly found on the trunk, limbs, face, and genital area. While the infection is generally harmless and self-limiting, it can be a cosmetic concern and may lead to secondary infections if not managed properly.
Are these warts?
Molluscum contagiosum, while referred to as water warts, is not the same as warts caused by the human papillomavirus (HPV).
Pictures
Below are some images of molluscum contagiosum presenting as single lesions or multiple lesions on different areas of the body.
The image below shows red and swollen bumps of inflamed molluscum contagiosum.
Who gets it?
Molluscum contagiosum is a common infection among children between the ages of 1 and 10 years, especially between 2 and 5 years. However, it can also affect teens and adults (especially those who are sexually active). It is uncommon in infants or before the age of 1 year.
The infection can be acquired at daycares, schools, pools, sports centers, or other communal areas, and it is more prevalent in hot, humid (tropical) climates. It is also commonly seen in athletes, wrestlers, and other contact supports.
People, especially children, with eczema or atopic dermatitis are more prone to getting it due to a disruption in the skin barrier.
Additionally, individuals with a suppressed immune system, such as those with HIV, cancer, transplant patients, or those taking immunosuppressive medications, are also more prone to it.
Cause and transmission
The condition is caused by the molluscum contagiosum virus (MCV), a DNA virus that belongs to the poxvirus family. MCV has four types, with the majority of cases caused by type 1. MCV type 2 is commonly seen in individuals with suppressed immune systems, such as those with HIV.
The molluscum contagiosum virus is transmitted through:
- Physical contact: Direct contact with the skin lesions of an infected person.
- Sexual contact, especially in adults.
- Contact with contaminated objects (infected fomites) such as towels, clothing, toys, razors, and helmets.
- The virus can also spread to different parts of the same individual’s body through autoinoculation, which can occur when a person scratches or touches the lesions and then touches another part of their body or by using a razor on the bumps or via electrolysis.
Contagiousness
Molluscum contagiosum is highly contagious and can easily spread within households, schools, and daycare centers. It can also spread in environments where close skin-to-skin contact is common, such as in sports teams or through sexual contact among adults.
It is important not to pop the lesions, as the cheesy material expressed contains the virus and can spread it to other parts of the body.
How long is it contagious?
Molluscum contagiosum bumps are contagious as long as the lesions are present. However, the virus resides in the top layer of skin cells, so there is no systemic infection (meaning the infection is not in the blood). Once the infection clears, a person is no longer contagious.
Is it an STD?
Molluscum contagiosum is considered a sexually associated infection when transmitted through sexual contact, resulting in lesions in the inner thighs and genital area, although it is not strictly classified as a sexually transmitted disease (STD).
Symptoms
The primary symptom of molluscum contagiosum is the appearance of small, pink, white, or flesh-colored bumps on the skin, called mollusca.
- These bumps are typically smooth, shiny, dome-shaped, and have a central dimple or a whitish core.
- They can range in size from 2 to 5 millimeters in diameter.
- Mollusca are often round, but their shape can vary.
- There might be a single lesion, multiple lesions, or a cluster of lesions.
- These bumps may be sometimes surrounded by areas of eczematous dermatitis. This is referred to as Molluscum dermatitis. This is more commonly seen in those with a history of atopic dermatitis/eczema.
- Sometimes, lesions may present on the eyelids and may rub against the eye, leading to conjunctivitis.
- The lesions are usually painless but can become itchy.
- In people with suppressed immune systems, the lesions can be extensive, and they may appear in atypical locations. These lesions often do not respond well to treatment, meaning they are refractory.
Areas affected
Molluscum contagiosum can affect any area of the skin but is most commonly found on the:
- Trunk: abdomen and back
- Armpits
- Arms: especially the inner side of the elbow (cubital fossa)
- Legs: especially behind the knees (knee pit or popliteal fossa)
- Face and neck
- Inner thighs and genital area, such as the penile shaft, vulva, vagina, anus, and perianal area (often related to sexual transmission)
Note: Palms and soles are not involved.
Stages
The development of molluscum contagiosum can be divided into four stages. It’s important to note that in medical literature, there are no well-defined phases; the stages below are based on how the disease evolves.
After the virus enters the skin, there are several weeks to months with no visible symptoms. This is called the incubation period, which typically lasts 2 to 6 weeks but can be as long as 6 months.
1. Beginning of molluscum contagiosum (Eruption of lesions)
The infection begins with the appearance of small, flesh-colored, white, or pink bumps on the skin. These bumps have smooth, waxy surfaces, unlike warts caused by HPV (human papillomavirus).
2. Progression (Larger bumps)
Over time, the lesions grow in size and develop a central dimple, a characteristic known as umbilication. These bumps are filled with cheesy material, which is essentially skin cells infected by the virus.
3. Inflammation (Regression)
As the body’s immune system starts to clear the virus, the lesions may become red, inflamed, swollen (often appearing pustular), crusted, or scabby. These lesions are referred to as inflamed molluscum contagiosum. This stage is described in the literature as the BOTE sign, meaning “beginning of the end.”
In some cases, another kind of inflammatory reaction can be seen, known as Gianotti-Crosti syndrome-like reaction. This is not very common and is characterized by the eruption of very itchy (pruritic), red, swollen bumps. This reaction tends to favor the extremities, especially the extensor aspects. Following this reaction too, the molluscum contagiosum bumps clear up.
It is important to note that not everyone will experience an inflammatory reaction as the virus clears. In some cases, the bumps may clear without undergoing any inflammatory changes.
4. Healing
When molluscum contagiosum bumps go away, they may leave behind white or pink-purple areas or spots that usually fade over time.
How long it lasts?
The duration of molluscum contagiosum varies from person to person and whether they are treated.
In untreated cases, molluscum contagiosum may last several months to resolve, usually 6 to 18 months. However, in some individuals, especially those with weakened immune systems, the lesions can persist for several years.
Can you get it more than once?
A person can get molluscum contagiosum more than once if they come into contact with a contaminated environment or a person with lesions again.
Complications
- Spread of bumps: The molluscum contagiosum bumps can easily spread on one’s body if one scratches or touches them and then touches an uninvolved area.
- Secondary Infection: If the bumps are picked or scratched, they may become secondarily infected by bacteria.
- Spots or scars: As the bumps heal, they may leave behind areas of altered pigmentation such as white spots. Although not common, sometimes the bumps may leave behind slightly indented or pitted scars.
- Eye irritation: Bumps on the eyelids can sometimes rub against the cornea, resulting in inflammation of the cornea called keratitis, or they can cause inflammation of the conjunctiva, leading to pink or red eye (conjunctivitis).
Diagnosis
The diagnosis of molluscum contagiosum is usually based on the appearance of the skin lesions. A healthcare provider may examine the bumps and look for the characteristic central dimple. Dermoscopy, a tool that can help examine these lesions at a higher magnification, can be useful for a thorough examination.
Sometimes, it may be difficult to differentiate molluscum contagiosum from other skin bumps, especially in those with suppressed immune systems where the lesions are larger and may even resemble skin cancer or infections. Additionally, early lesions can be confused with warts or herpes (Read more: Molluscum Contagiosum vs Herpes).
In doubtful cases, a biopsy or scraping of the lesion may be performed, and the tissue is sent to a pathology lab to confirm the diagnosis.
Pathology (under the microscope)
Although molluscum contagiosum is not biopsied very often, I have had the chance to see some classic cases under the microscope.
Molluscum contagiosum lesions show large, eosinophilic, cytoplasmic inclusion bodies in skin cells known as molluscum bodies or Henderson-Paterson bodies. These inclusion bodies are formed due to the replicating virus and are characteristic of Molluscum contagiosum.
Read more: Molluscum contagiosum treatment and prevention
Takeaway
While harmless, it is important to know how molluscum contagiosum looks and how it progresses. Any new or unusual skin bumps should be examined by a doctor to get the right diagnosis and treatment.
References
- Meza-Romero R, Navarrete-Dechent C, Downey C. Molluscum contagiosum: an update and review of new perspectives in etiology, diagnosis, and treatment. Clin Cosmet Investig Dermatol. 2019 May 30;12:373-381. doi: 10.2147/CCID.S187224. PMID: 31239742; PMCID: PMC6553952. Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6553952/
- Hebert AA, Bhatia N, Del Rosso JQ. Molluscum Contagiosum: Epidemiology, Considerations, Treatment Options, and Therapeutic Gaps. J Clin Aesthet Dermatol. 2023 Aug;16(8 Suppl 1):S4-S11. PMID: 37636018; PMCID: PMC10453394. Link:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10453394/
- Berger EM, Orlow SJ, Patel RR, Schaffer JV. Experience With Molluscum Contagiosum and Associated Inflammatory Reactions in a Pediatric Dermatology Practice: The Bump That Rashes. Arch Dermatol. 2012;148(11):1257–1264. doi:10.1001/archdermatol.2012.2414. Link: https://jamanetwork.com/journals/jamadermatology/fullarticle/1351941
- Schaffer JV, Berger EM. Molluscum Contagiosum. JAMA Dermatol. 2016;152(9):1072. doi:10.1001/jamadermatol.2016.2367. Link: https://jamanetwork.com/journals/jamadermatology/fullarticle/2547245
Disclaimer: This article is for information purposes only and does not replace medical advice.