Molluscum Contagiosum (MC) is a common skin infection caused by the Molluscum Contagiosum Virus, a member of the poxvirus family. This condition typically manifests as small, raised bumps that are generally benign and resolve on their own over time. Many other dermatological issues, ranging from viral infections to structural skin conditions, can produce similar-looking bumps, leading to diagnostic confusion. Correctly identifying MC requires a careful examination to differentiate it from these various mimics.
The Defining Features of Molluscum Contagiosum
The lesions associated with Molluscum Contagiosum are small, firm, dome-shaped papules, typically ranging from 2 to 5 millimeters in diameter. Their color often matches the surrounding skin, appearing pink, white, or pearly, sometimes with a waxy sheen. The most specific feature is a small central dip or depression, known as umbilication, which often contains a white core.
These papules can appear almost anywhere, though they are most frequently seen on the trunk, limbs, and face, especially in children. In adults, they are sometimes found in the genital area. MC lesions usually remain separate and distinct, though they can cluster together in localized patches. The infection often persists for months or even years before natural resolution.
Viral and Bacterial Lesions That Look Similar
Many infectious skin conditions can present with papules easily confused with Molluscum Contagiosum. Verrucae, commonly known as warts, are a frequent viral mimic caused by the Human Papillomavirus (HPV). Warts, particularly flat or common warts, can appear as small, skin-colored bumps resembling MC lesions in size and distribution.
Warts universally lack the central umbilication found in MC papules. They tend to have a rougher, more irregular surface texture, sometimes described as cauliflower-like, unlike the smooth, dome-shaped MC lesions. Warts often develop small black dots (clotted blood vessels), a feature not seen in uncomplicated molluscum.
Folliculitis is often bacterial or fungal in origin and involves the inflammation of one or more hair follicles, resulting in small, red bumps or pustules. Folliculitis lesions are centered directly around a hair follicle, differentiating them from MC, which develops independently of follicular structures.
These bumps are often red and tender, and they may contain a visible collection of pus. The presence of pus and the association with hair follicles distinguish folliculitis from the pearly, umbilicated papules of Molluscum Contagiosum.
Non-Infectious Conditions That Resemble MC
Several non-infectious conditions can structurally resemble the papules of Molluscum Contagiosum. Milia are tiny, benign, superficial cysts that form when keratin becomes trapped beneath the skin’s surface. These lesions appear as small, firm, white or yellowish bumps, and their pearly appearance often leads to confusion with molluscum.
Milia are generally smaller than MC lesions, often only 1 to 2 millimeters in diameter, and completely lack the characteristic central umbilication. Unlike transmissible MC, milia are not contagious and are a structural anomaly. They frequently appear on the face, especially around the eyes and nose.
Keratosis Pilaris (KP) can be confused with a widespread molluscum outbreak. This condition is caused by the accumulation of excess keratin, which forms plugs within the hair follicles, resulting in numerous small, rough bumps. KP often appears on the back of the upper arms, thighs, and sometimes the cheeks, presenting as patches of texture rather than isolated papules.
KP lesions feel rough or gritty to the touch, often described as feeling like sandpaper, which is distinctly different from the smooth, waxy surface of MC lesions. The widespread distribution, rough texture, and lack of umbilication in KP help differentiate it from the viral infection.
Distinguishing Features and Medical Consultation
The presence of the central umbilication remains the most reliable clinical sign pointing toward Molluscum Contagiosum. Conversely, the absence of this dimple, coupled with a rough, irregular texture, suggests a common wart.
Folliculitis is likely when a lesion is red, tender, and centered on a hair follicle, especially if it contains pus. Milia are distinguishable by their smaller size, bright white color, and completely smooth, non-dimpled surface. Keratosis Pilaris is identified by its widespread, sandpaper-like texture and preference for the upper arms and thighs.
If visual evidence is ambiguous, a healthcare professional may use a dermatoscope to magnify the lesion’s structure. Rarely, a small biopsy is necessary to confirm the diagnosis by examining the tissue sample under a microscope. It is important to seek medical advice for lesions that are persistent, rapidly changing, painful, bleeding, or spreading quickly.