Dermoscopy of molluscum contagiosum

Abstract

Molluscum contagiosum is a common benign viral infection affecting children, sexually active adults, and immunocompromised individuals. We present the case of a 28-year-old male with advanced HIV who developed scattered pink papules over a 2-year period. Through clinical, dermoscopic, and histopathologic evaluations, a diagnosis of molluscum contagiosum was eventually confirmed. Dermoscopy revealed numerous whitish round to polylobular amorphous structures with visible branching vessels. Histopathologic examination showed cup-shaped inverted lobules of hyperplastic squamous epithelium with eosinophilic intracytoplasmic inclusion bodies. This case highlights the importance of dermoscopy in the accurate diagnosis of molluscum contagiosum in immunocompromised patients, reinforcing its role as a non-invasive diagnostic tool in dermatology.

Introduction

Molluscum contagiosum, a benign viral infection, is commonly observed in children, sexually active adults, and immunocompromised individuals. We present the case of a 28-year-old male with advanced HIV and a 2-year history of scattered pink papules. Dermoscopic and histopathologic evaluation ultimately confirmed the underlying diagnosis. This report emphasizes the diagnostic value of dermoscopy, particularly in identifying atypical lesions in immunocompromised patients.

Case report

A 28-year-old man presented with a 2-year history of scattered pink papules over the trunk and limbs (Figure 1). His clinical history was notable for recently diagnosed advanced human immunodeficiency virus (HIV) infection, for which he had started on highly active anti-retroviral therapy (HAART) 5 months earlier. At the time of presentation, his CD4 count was 90 cells/microlitre.

Figure 1.

Clinical appearance shows a pink papule with a smooth surface over the right arm.

Dermoscopic appearance

Dermoscopic evaluation revealed numerous whitish round to polylobular amorphous structures, accompanied by visible branching vessels located both in between and around the lesion (Figure 2).

Figure 2.

Dermoscopy shows multiple whitish round to polylobular amorphous structures, alongside branching blood vessels dispersed both within and at the periphery of the lesion.

Histological diagnosis

A 5 mm punch biopsy was performed. Histopathologic examination revealed cup-shaped inverted lobules of hyperplastic squamous epithelium expanding into the dermis with eosinophilic intracytoplasmic inclusion bodies (Henderson-Paterson bodies) (Figure3(a) and (b)).

Figure 3.

Histopathology shows (a) cup-shaped inverted lobules of acanthotic epidermis with expansion into the dermis (Magnification × 10) (b) the presence of eosinophilic intracytoplasmic inclusion bodies (Henderson-Paterson bodies) (Magnification × 20).

Hence, a diagnosis of molluscum contagiosum was made.

Discussion

Molluscum contagiosum is a benign cutaneous infection commonly seen in children, sexually active adults, and immunocompromised individuals. It typically presents as multiple umbilicated pink to skin-coloured papules with a translucent, glossy appearance. ¹ While clinical diagnosis suffices in most cases, dermoscopy can significantly enhance diagnostic accuracy by revealing the presence of vessels and lesional orifices. ² This is especially useful in immunocompromised individuals with lesions that are atypical, extensive, or lack umbilication, as in our case.

Dermoscopic examination often reveals central umbilication surrounded by white-yellowish polylobular amorphous structures. Vascular patterns may vary, including crown-like, radial, dotted or combinations thereof. Histopathologically, the central structures correspond to lobulated endophytic epidermal hyperplasia with intracytoplasmic viral inclusions (Henderson-Paterson bodies). As the infection progresses, dermal displacement occurs, thereby shifting vessels to the periphery. ¹

The main dermoscopic differentials for molluscum contagiosum include conditions with sebaceous differentiation, such as sebaceous hyperplasia, sebaceous adenoma, and naevus sebaceous. These can share features such as the ‘crown arrangement’ vascular pattern and central yellow clods. Key dermoscopic differences include the distinct round or four-leaved clover-like central white structures in molluscum contagiosum, as described by Ku et al., ³ and the more regularly distributed, larger, and whiter clods, compared to the smaller, yellowish clods of sebaceous lesions. ⁴ Molluscum contagiosum has also been reported to mimic other conditions. Navarrete-Dechent et al. described a case of desmoplastic tricholemmoma on the eyelid with similar dermoscopic features of crown vessels and ill-defined white areas, suggesting that solitary eyelid lesions with this pattern should be biopsied to exclude malignancy. ⁵ Additionally, Wang et al. reported a case of molluscum contagiosum mimicking condyloma acuminatum, with peripheral crown-like vascular structures but lacking the characteristic white-to-yellow amorphous structures, which can assist in differentiation. ⁶

Conclusion

Familiarity with the characteristic dermoscopic features of molluscum contagiosum is helpful as it offers a non-invasive means of diagnosing this common skin infection.