Extensive Molluscum Contagiosum With Atypical Verrucous Lesion on Scalp Mimicking Warts in an Immunocompromised Host

Dear Editor, Molluscum contagiosum is a common, self-limited viral skin infection caused by a poxvirus. It usually presents as small, dome-shaped, flesh-colored papules with central umbilication, most often seen in children, sexually active adults, or immunocompromised individuals. However, in immunocompromised individuals, extensive involvement or atypical morphologies of molluscum may be seen. Herein, we report an unusual morphology of molluscum contagiosum. A 22-year-old male presented with a 9-month history of multiple skin-colored, umbilicated papules and hyperkeratotic verrucous lesions. He had been diagnosed with B-cell acute lymphoblastic leukemia 1.5 years ago and was receiving monthly vincristine 2 mg intravenous injections along with daily oral prednisolone 60 mg, methotrexate 25 mg weekly, and 6-mercaptopurine 50 mg daily. Cutaneous examination revealed multiple rounded, skin-colored, dome-shaped umbilicated papules measuring 0.2 × 0.2 cm to 0.5 × 0.5 cm, scattered on the face, scalp, neck, chest, and back, clinically suggestive of molluscum contagiosum [Figure 1a and 1b]. Additionally, multiple skin-colored to slightly hyperpigmented and hyperkeratotic papules were seen scattered on the neck, chest, and back, with some lesions showing pseudokoebnerization [Figure 1c], suggestive of plane warts. Scalp examination showed multiple well-defined, large, verrucous, and hyperkeratotic plaques ranging from 1 × 1 cm to 5 × 6 cm in size; a few of the larger plaques also exhibited areas of umbilication. On investigation, he was found to have bicytopenia with a hemoglobin level of 9 g/dL (macrocytic, hypochromic) and a total leucocyte count of 1350 cells/mm3. Tests for viral markers (Hepatitis B surface antigen, anti-hepatitis C antibodies, HIV-1 and HIV-2 antibodies) were negative. A punch biopsy was taken from one of the verrucous plaques on the scalp, with clinical differentials of verruca vulgaris and molluscum contagiosum. Histopathology showed prominent acanthosis and papillomatosis with eosinophilic inclusion bodies within the cytoplasm and also lying loose in the stratum corneum, consistent with Henderson-Patterson bodies of molluscum contagiosum [Figure 2a and 2b]. The patient was advised to apply salicylic acid 16.7% + lactic acid 16.7% combination over the verrucous plaques and 10% potassium hydroxide solution once daily over plane warts and smaller molluscum lesions. He reported a reduction in lesion size after 1 month of treatment.Figure 1: (a) Multiple large, verrucous, and hyperkeratotic plaques on scalp, larger plaques also showing areas of umbilication; (b) skin colored, dome-shaped umbilicated papules on face, suggestive of molluscum contagiosum; (c) multiple skin colored to slightly hyperpigmented and hyperkeratotic papules scattered on the neck and chest with some lesions showing pseudokoebnerization, suggestive of plane wartsFigure 2: (a) Low magnification revealed prominent acanthosis and papillomatosis with eosinophilic inclusion bodies within the cytoplasm and also lying loose in the stratum corneum, consistent with Henderson-Patterson bodies of molluscum contagiosum (Hematoxylin and eosin, × 100); (b) higher magnification showing Henderson-Patterson bodies (Hematoxylin and eosin, × 400)Molluscum contagiosum typically appears as skin-colored, dome-shaped papules with central umbilication. It is a common viral infection in school-aged children, primarily affecting the face, neck, and trunk. In adults with normal immunity, it often involves the genital area and is considered a sexually transmitted infection.[1] Unusual presentations can occur on the soles or palms—particularly in immunocompromised individuals—mimicking other conditions like verruca vulgaris.[2] Molluscum contagiosum lesions can sometimes exhibit a verrucous (hyperkeratotic and disfiguring) appearance, particularly in specific cases like those with large lesions or in individuals with HIV.[3,4] Verrucous morphology in molluscum contagiosum is characterized by a rough, wart-like surface, distinct from the smoother, dome-shaped appearance typically seen in this infection. To the best of our knowledge, such extensive verrucous plaques of molluscum on the scalp have not been previously documented in the literature. Other atypical presentations of molluscum contagiosum may mimic epidermoid cysts, benign adnexal tumors, or even Paget’s disease.[5] Warts are caused by human papillomavirus (HPV) and show large basophilic keratohyaline granules of variable shapes and sizes in the keratinocytes. Molluscum contagiosum, on the other hand, shows uniformly appearing eosinophilic intracytoplasmic inclusions in the keratinocytes, different from the granules seen in warts.[3] Several treatments are available for molluscum contagiosum lesions, including potassium hydroxide, salicylic acid, hydrogen peroxide, cryotherapy, curettage, radiofrequency ablation, and pulsed dye laser. Treatment should be based on the location, size, number of lesions, and the patient’s immunity status because of the self-limited nature of molluscum contagiosum. Our report highlights the atypical morphology of molluscum contagiosum involving the scalp in immunocompromised patients. This will help clinicians in the easy and early diagnosis of such atypical morphologies. Authors’ contributions The manuscript has been read and approved by all authors. All authors meet authorship criteria, and the manuscript represents honest work. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Use of artificial intelligence (AI) The preparation of this manuscript was carried out entirely by the authors without the use of artificial intelligence technologies.