An Eczematous Eruption on the Arm.

A 74-year-old Japanese man presented with a 2-year history of a pruritic eczematous eruption. The eruption occurred 3 years after he was diagnosed with chronic renal failure. He had atrial fibrillation and had been treated with warfarin for 5 years. He has a past history of childhood asthma. Clinical examination revealed itchy lichenificated and/or eczematous eruptions on the trunk and extremities [Figure 1a]. A peripheral blood sample test showed a normal leukocyte count of 6100/μl with high levels of eosinophils (2196/μl) and a high RAST index that was specific to Dermatophagoides pteronyssinus. Serum thymus and activation-regulated chemokine level was 909 (normal, <450 pg/mL), and the IgE level was normal. Dermoscopic examination showed? a round whitish area without vascular complex surrounded by small, whitish irregular areas [Figure 1b]. A skin biopsy was performed, and the site was marked with skin marking pen [Figures 1 and 2].

Figure 1

(a) There was an eczematous lesion on the upper arm. (b) Dermoscopic findings: Whitish areas without an orifice and without vessels

Figure 2

(a) Low-powered magnification of a histopathological specimen showed a well-defined lobule containing enlarged keratinocytes with intracytoplasmic viral inclusions (Hematoxylin and eosin [H&E] staining, 40×). (b) A high-powered view of spongiosis and perivascular infiltrate consisting of lymphocytes and eosinophils (H&E staining, 200×)

Question

What is your diagnosis?

Answer

Molluscum contagiosum.

Discussion

Histopathologically, there were an acanthotic epidermis with spongiosis, and a superficial and mid-dermal perivascular inflammatory infiltrate composed of lymphocytes and scattered eosinophils. In addition, we observed a crateriform epidermal architecture containing both keratinous materials and molluscum bodies in the invaginated center. Based on these findings, we made a diagnosis of molluscum contagiosum in an eczematous background.

Molluscum contagiosum is a common skin infection caused by a poxvirus and generally occurs in children. Molluscum contagiosum lesions typically appear as single or multiple, small flesh-colored and translucent papules with a characteristic central umbilication. Since Bateman's original description, molluscum contagiosum has been considered a non-inflammatory condition both clinically and histopathologically.[1] However, several types of inflammatory reactions can occur in association with molluscum contagiosum.[23] Typical dermoscopic features of molluscum contagiosum include orifices and specific vascular patterns.[4] Although the presence of an orifice is an important characteristics in identifying molluscum contagiosum,[5] our patient lacked orifices and specific vascular patterns. Thus, in case of the diagnosis remains inconclusive due to the limits of dermoscopy, histopathology can help confirm the diagnosis. Atypical clinical manifestation of molluscum contagiosum may be linked to the unique dermoscopic features. Therefore, findings of the present case and previous studies suggest that molluscum lesions can be difficult to recognize when the lesions are superimposed by eczema as well as when the lesions lack typical dermoscopic patterns of molluscum contagiosum.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.