When An Adult Patient Presents With Red Spots On The Feet

By G. “Dock” Dockery, DPM, FACFAS

It is late in the summer when a 29-year-old Caucasian female, employed as a medical assistant in your foot and ankle clinic, presents with a two-day history of red spots on her feet. The red spots became small fluid-filled vesicles, which are present mostly on the soles. She says she has broken one of the small vesicles and it expressed a clear fluid.

The lesions are causing mild discomfort but are not very pruritic. Otherwise, she feels a little fatigued and reports a slightly elevated oral temperature today. Additionally, she reports a mild headache and a slight sore throat. She has experienced these symptoms for a few days but has not missed any work this week. She has not experienced any chills, nausea, vomiting, diarrhea, abdominal pain, joint pains or difficulty breathing.

She denies any out of state or foreign travel. However, she was visited last week by her sister and niece, who live in another state. The patient has had no known exposures to any new makeup, chemicals, paints, toxins, irritants or other potential allergens. She is taking birth control pills but denied taking any other medications, vitamins or supplements. No one else in her household or within her family had any similar conditions. She has never had similar signs or symptoms in the past that she can recall.

What The Exam Revealed
During the physical examination, we note several small tense vesicular lesions and a few small macules with an erythematous or mauve border on the plantar aspects of both feet. Careful examination also shows similar lesions on the hands. There are no targetoid lesions or any other distinctive skin lesions on the face, torso, arms or legs. There are also no color changes or inflammation involving the eyes or ears. The patient’s vital signs are normal except for a slight elevation of the oral temperature. The remaining portion of the physical examination is within normal limits and the patient has no other clinically significant skin conditions.

A Closer Look At Hand-Foot-Mouth Disease
The most likely diagnosis is hand-foot-mouth disease (HFMD). The disease is an acute, mild but moderately contagious viral infection, which is common in preschool children. Those with the disease are most contagious during the first week of the illness. This illness is usually caused by Coxsackie A16 but it can be caused by other Coxsackie viruses (A5, A7, A9, A10, B2, and B5 strains) as well as Enterovirus 71. Coxsackievirus is a subgroup of the enteroviruses and is a member of the family Picornaviridae. This family consists of small, nonenveloped, single-stranded RNA viruses. Most reported cases occur in summer and early autumn in temperate climates. However, cases can occur sporadically all year long.

Hand-foot-mouth disease is a self-limiting disease with resulting acquired immunity but a second episode can occur following infection with a different member of the Enterovirus group. This disease is most common in children under 10 years of age but one may see this with some frequency up until puberty. Adults can get it but this is much less common. When adolescents and adults are infected, their symptoms are generally mild because they have most often developed prior immunity. However, I have seen adults with HFMD who have presented with significant symptoms, probably due to a lack of exposure at an earlier age.

The usual period from initial infection to the onset of signs and symptoms (incubation period) is three to seven days. Fever is usually the first sign of HFMD. This is followed by a sore throat, malaise, abdominal pain and headache. In one or two days after the fever begins, the first macular lesions typically appear on the buccal mucosa, tongue or hard palate. These mucosal lesions rapidly progress to vesicles that erode and become surrounded by an erythematous halo. It is rare to see the original mouth lesions because they rapidly become ulcerated and resolve in about five days.

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