Boy presents with unusual sore on forearm
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A 9-year-old boy from southern California was taken to his primary care provider’s office for evaluation of an unusual sore on his forearm.
The history of the chief complaint was that he had a “bug bite” at the same spot a couple of weeks earlier when he and his family were traveling and camping in northern California. At the time he first noticed the lesion, it appeared to be a red bump that he had scratched, and he may have scratched off the causative insect, but he did not identify it. However, there was a small amount of blood noted. He had no fever or other symptoms associated with it, and the parents did not notice the lesion until it persisted and enlarged somewhat. At the initial visit, the lesion was thought to be common pyoderma or impetigo, and he was given oral cephalexin.
He returns 2 weeks later due to the cephalexin having no effect, even though he was not always good at taking it every day. The lesion significantly expanded into an irregularly shaped ring (Figure 1), although he remains asymptomatic. He is otherwise healthy and feels well. The primary care physician sent Lyme titers, which returned negative.
What’s your diagnosis?
A. Cutaneous sporotrichosis
B. MRSA cellulitis
C. Early localized Lyme disease
D. Southern tick-associated rash illness
Answer and discussion:
The best answer is early localized Lyme disease caused by the Ixodes pacificus tick. Although it remains very uncommon there, northern California leads the Western coastal areas in reported cases of Lyme disease. In known cases of Lyme disease, screening serologies are often negative — up to 50% in early localized disease — especially with single lesions. Therefore, negative screening serologies do not rule it out. In typical erythema migrans (EM) cases in an area known to have the vector (the Ixodes tick), serologies are often not done, but rather diagnosis is usually made on the recognition of the EM lesion. When it becomes important to document the diagnosis, such as infection beyond cutaneous manifestations, the recommendation is to use a two-tiered serologic algorithm (see the 2021-2024 Red Book, pages 484-485). The patient was given a 2-week course of amoxicillin and the motivation to take it, and the lesion resolved without complication.
Sporotrichosis is a chronic infection of the skin with the fungus Sporothrix schenckii when it becomes implanted at the cutaneous site of minor injury, classically from a rose bush thorn. It typically begins as a painless papular lesion that persists and slowly grows, and eventually ulcerates, often containing secondary lesions (Figure 2). It also may involve the regional lymph node (lymphocutaneous sporotrichosis). There is no ring associated with the lesion.
MRSA cellulitis would not be expected to resolve with a second-generation cephalosporin. However, the appearance would be a more diffuse, painful erythema, without central clearing, in a patient who may have fever and possible abscess formation.
Southern tick-associated rash illness, or STARI, is an infection of unknown etiology that also produces a ringlike skin lesion similar to Lyme disease (Figure 3). However, there is no progression to other systemic manifestations, unlike many cases of Lyme disease. Therefore, treatment is probably not necessary. Nonetheless, many patients are treated for early localized Lyme disease out of uncertainty. STARI is also highly geographic. It is spread by the lone star tick (Amblyomma americanum), which has a geographic distribution encompassing a large portion of the U.S. — from mid-America to all of the Eastern states and most of the Southern states but not in the Western half of the country. Therefore, one would not expect to see STARI in California.
My thanks go to Michael Cater, MD, of Children’s Hospital of Orange County, California, for this case.
Columnist comments:
I remain mystified as to why well-educated health care workers, many being physicians, continue to refuse to get the COVID-19 immunization, even though these products have passed through the same rigorous approval process (although “fast tracked”) as all those immunizations they may (or may not) have received previously. I can only assume that they are afraid to admit a terrifying, personal fear of needles, at least that’s what I would like to think. Otherwise, it makes no sense. We endured a long educational process of accepting the science of the endless number of facts committed to memory in order to be competent, scientifically grounded providers. Otherwise, we would all be no better than medieval barbers. Why would the science of vaccines be any different? It has ONLY been by public cooperation of accepting vaccine science that we no longer have contagious diseases such as polio, diphtheria, smallpox, Hemophilus influenzae type b, pertussis, hepatitis B, measles, rubella, mumps, pandemic influenza, etc., killing or crippling hundreds of thousands every year. Perhaps it’s a generational thing. I think if a person has lived during a time before the elimination or near-elimination of these diseases, they would be less likely to doubt the science. That’s where knowing history is important. But again, I cannot believe that medical providers are that dumb or poorly educated in history. Therefore, I rotate back to the “fear of needles” theory. Perhaps some hypnosis or biofeedback will help them.
For more information:
Brien is a member of the Infectious Diseases in Children and Infectious Disease News Editorial Boards, and an adjunct professor of pediatric infectious diseases at McLane Children's Hospital, Baylor Scott & White Health, in Temple, Texas. He can be reached at jhbrien@aol.com.
Reference:
American Academy of Pediatrics. Committee on Infectious Diseases. Red Book. Report of the Committee on Infectious Diseases. Academy of Pediatrics; 2021. https://redbook.solutions.aap.org/redbook.aspx. Accessed Nov. 11, 2021.