Review Question - QID 108550

This child’s physical exam and history indicate that he has molluscum contagiosum, a skin infection caused by the poxvirus. This virus has double-stranded, linear DNA.

Molluscum contagiosum is a skin infection caused by the poxvirus family. This family of viruses have double-stranded, linear DNA enclosed within a complex capsule. Other members include smallpox and cowpox. The presentation of the rash – firm, flesh-colored papule(s), often with central indentation (umbilication) – is classic for molluscum contagiosum. The papules are typically non-painful and non-pruritic.

Figure A shows the flesh colored papules with central umbilication that are characteristic of molluscum contagiosum.

Incorrect Answers:
Answer 1: Both rubella and measles are single-stranded RNA viruses from the togavirus and paramyxovirus families, respectively. Both are characterized by a red, maculopapular rash that originates at the head and moves downwards. Patients with rubella typically have a more benign rash that is pink or light red, and that lasts 1-3 days. Those with measles typically have a more severe rash that is a dark red or brownish color (at times appearing hemorrhagic) and that lasts for up to one week.

Answer 2: The reovirus family is the only viral family with double-stranded, linear RNA. It includes rotavirus, which causes diarrhea in children, and coltivirus, which causes Colorado tick fever. These are not common causes of childhood rashes.

Answer 3: Parvovirus is a single-stranded, linear DNA virus that causes erythema infectiosum (fifth disease). This childhood rash is characterized by a red, “slapped cheek” coloring on the face and a “lacy” reticular rash over the body that spares the palms and soles.

Answer 5: Papillomaviruses such as HPV have double-stranded, circular DNA. HPV type 1 causes cutaneous warts. These typically appear on the palms and soles and can take on a variety of clinical presentations (e.g., flat-topped papules, single papules with projections, and keratotic papules). However, the rash presented in this question is more consistent with molluscum.

Bullet Summary:
Molluscum contagiosum classically presents as firm, flesh-colored papules with central indentation; it is a member of the pox virus family, which has double-stranded, linear DNA and a complex capsule.