Woman, 32, With Crusty Red Blisters

DISCUSSION
HFMD is an acute viral illness most often affecting children younger than 5 and occurring in summer to early fall months. HFMD manifests with fever and papulovesicular eruptions; lesions often appear in the oral cavity first, spreading to the palms, soles, and buttocks. Route of transmission is usually fecal-oral or through respiratory droplets, oral secretions, or direct contact with fluid-filled vesicles.^6-8 The highly contagious nature of the virus causes it to spread to close contacts and family members and leads to outbreaks in schools and daycare centers.^9,10

In the United States, the most common etiology of HFMD is coxsackievirus A16.⁷ Another causative agent, enterovirus 71 (EV71), has been found responsible for HFMD epidemics in southeast Asia and Australia.^11,12 Recently, the coxsackievirus A6 (CV A6) strain has been linked to outbreaks of HFMD.^7,9 This strain may produce an atypical manifestation of skin lesions on the face, trunk, and extremities. The lesions may also appear larger than usual and have a vesiculobullous rather than the more typical papulovesicular appearance. The course of the illness differs in severity depending on the strain of the virus causing HFMD.⁹

CLINICAL PRESENTATION
The acute phase of HFMD typically begins with prodromal symptoms such as fever, malaise, and sore throat. Erythematous ulcerations usually appear in the oral cavity first (see Figure 4) and often cause symptoms such as sore throat, dysphagia, or dryness. As the disease progresses, cutaneous lesions spread to the face, extremities, interdigital areas (see Figure 5), trunk, and perianal area (which may cause dysuria). The lesions may initially appear as erythematous macules or papules, transforming to vesicles as the disease progresses. The mucocutaneous lesions are usually asymptomatic but can be tender to touch or pressure and may leak fluid.^7,10

In only a few cases—caused by CV A6—have lesions in the scalp been reported; the mechanism of action is unknown.¹⁰ Instances of lesions invading the nails have been reported, causing desquamation and shedding. This condition is known as onychomadesis.^9,11

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