Sir,

Molluscum contagiosum (MC) is a common, benign epidermal contagious lesion caused by the MC virus (MCV) virus – a double-stranded DNA poxvirus – that affects both children and adults, including healthy and immunocompromised individuals. It is a very common skin infection, reported in all age-groups, but when MC occur in children less than one-year-old a vertical transmission could be suspected. The annual incidence varies between 2.4% and 12.8%. Children under 5 years are most affected [1].

The predominant virus type in children is MCV-1, whereas MCV-2 is more often associated with immunosuppression or sexually transmitted infections [2]. Infection occurs through direct contact with infected skin, contaminated objects or autoinoculation. Incubation period varies from 2 to 6 weeks, very often it is difficult to precise the moment of contamination [3]. It is a self-limited skin infection, but highly contagious to patient and to other children.

Patients infected with MCV present firm rounded papules from 2 to 5 mm, pink or skin-coloured, with a shiny and umbilicated surface. Spontaneous regression is characterized by erythema and edema – a phenomenon called “beginning of the end” (BOTE) sign. Diagnosis is based on clinical grounds and rarely a biopsy is necessary. Dermoscopy could be of great value in some cases [4].

MC can rarely occur on the scalp, along with similar lesions on other sites, but MC localized only to the scalp in small children is quite infrequent [5].

We present a 2.5-year-old boy, who was seen in Dermatology for skin-coloured lesions spread on the scalp. There was a history of a haircut a few weeks prior to present consultation in a children’s barber shop. Her mother denied any symptoms related to skin disease but reported the evolution of lesions. Dermatological examination revealed scattered skin colored-yellowish papules on the scalp, no central umbilication was noticed. On dermoscopy we observed a central white–yellow, polylobular amorphous structure and peripheral “crown” vessels. First clinical diagnosis was juvenile xanthogranuloma, but dermoscopy (Figs. 1 and 2) and clinical history confirmed the diagnosis of multiple MC.

	Figure 1: Clinical presentation of mollusca contagiosa on the scalp.
	Figure 2: Dermoscopy of Mollusca contagiosa on the scalp showing central white–yellow, polylobular amorphous structure and peripheral “crown” vessels.

Treatment with topical KOH was initiated and close follow-up was recommended.

MC are common among children and infants. The affection of the scalp, however, is rare. Dermoscopy of MC classically reveals a central white–yellow, polylobular amorphous structure with a central pore/umbilication and peripheral “crown” vessels – a ring of linear/branched vessels around the lesion, classically not crossing the central lobules [6]. The central orifice/umbilication was seen in 96.68% on dermoscopy vs 50.24% clinically [4]. Vessels were seen in 89.10% on dermoscopy vs 6.16% clinically. As shown by our case, umbilication might be absent in MC on the scalp. Vascular morphologies include crown (72.34%), radial (54.25%), punctiform or dotted (20.21%) (correlated with inflammation/excoriation/perilesional eczema) patterns, and mixed vascular patterns – ”flower pattern” (19.68%) [7].

Treatment in general is possible by medical and physical methods. Curettage, cryotherapy and laser are effective. Topical treatments include dichloroacetic acid, cantharidin, glycolic acid, lactic acid, salicylic acid, imiquimod, podophyllotoxin, tretinoin, berdazimer, cidovovir, and sinecatechin [4]. A systematic review counted KOH among the more effective treatments [8], especially in children [9]. A comparative trial with 40 patients between 1-18 years with clinically diagnosed MC suggested that 10% KOH solution was more effective than 5% imiquimod cream. The clearance rate after 12 weeks was 85% for KOH versus 50% for imiquimod. KOH was also less expensive [10].

The present case highlights the unusual localization of MC on the scalp in an immunocompetent child, the usefulness of dermoscopy for ruling out other skin disorders, especially juvenile xanthogranuloma.

REFERENCES

1.  Hebert AA, Bhatia N, Del Rosso JQ. Molluscum Contagiosum:Epidemiology, Considerations, Treatment Options, and Therapeutic Gaps. J Clin Aesthet Dermatol. 2023;16(8 Suppl 1):S4-11.

2.  Gewirtzman A, Bobrick L, Conner K, Tyring SK. Epidemiology of Sexually Transmitted Infections. In:Gross G, Tyring S (eds) Sexually Transmitted Infections and Sexually Transmitted Diseases. Berlin, Heidelberg:Springer 2011:13-34.

3.  Santacroce L, Magrone T. Molluscum Contagiosum Virus:Biology and Immune Response. In:Rezaei N. (eds) Poxviruses. Advances in Experimental Medicine and Biology, vol 1451. Cham:Springer. 2024:151-70.

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5.  Arora N, Wittmer A, Najmi M, Justus J, Hendrick S. An Atypical Presentation of Molluscum Contagiosum in a Newborn. Cureus. 2024;16:e63932.

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7.  Ianhez M, Cestari Sda C, Enokihara MY, Seize MB. Dermoscopic patterns of molluscum contagiosum:a study of 211 lesions confirmed by histopathology. An Bras Dermatol. 2011;86:74-9.

8.  Chao YC, Ko MJ, Tsai WC, Hsu LY, Wu HY. Comparative efficacy of treatments for molluscum contagiosum:A systematic review and network meta-analysis. J Dtsch Dermatol Ges. 2023;21:587-97.

9.  Giner-Soriano M, TeixidóC, Marsal JR, Díez O, Pera H, Vlacho B, et al. Randomized placebo-controlled clinical trial on efficacy and safety of topical 10% Potassium hydroxide for molluscum contagiosum treatment in children. J Dermatolog Treat. 2019;30:750-6.

10.  Chathra N, Sukumar D, Bhat RM, Kishore BN, Martis J, Kamath G, et al. A comparative study of 10% KOH solution and 5% imiquimod cream for the treatment of Molluscum contagiosum in the pediatric age group. Indian Dermatol Online J. 2015;6:75-80.