Boy presents with worsening lesion on forehead
Click Here to Manage Email Alerts
A 12-year-old boy was seen by his primary care physician for a worsening lesion of unknown etiology on his forehead.
He stated that he first noted something feeling unusual, like a stinging sensation in the same area a few days earlier that he thought was simply insect bites. By the next day, he noted a couple of small pimple-like “blisters.” He denied any trauma but does complain that his baseball cap headband fits right over the area in question and is irritating. Over the next 48 hours, the lesions grew in size (coalesced), and he was brought into his clinic for evaluation. His PCP swabbed the lesion for bacterial culture and prescribed oral dicloxacillin for presumed Staphylococcus aureus cellulitis.
Later that same day, he returned to his doctor’s office with low-grade fever and some mildly uncomfortable, left anterior cervical lymphadenopathy. He also complained bitterly about the taste of the dicloxacillin suspension (he cannot swallow capsules). It was felt that with the rapid progression of this unknown lesion, he should be admitted to the hospital for evaluation and IV antibiotics.
His past medical history was that of a previously healthy 12-year-old male, with no other complaints. His immunizations were up to date. The patient had a typical case of chickenpox when he was 6 years of age.
Examination upon arrival reveals normal vital signs, with no fever at this time. The lesion is accompanied by considerable painful swelling of the forehead, with an unusual-appearing lesion with surrounding erythema (Figures 1 and 2). The admitting lab test includes only a normal complete blood count (CBC) and additional swabs of the fluid in the lesion for bacterial, fungal and viral cultures (this case predates rapid testing, such as PCR, as well as the varicella vaccine), with Gram stain pending.
What’s your diagnosis?
A. Bullous impetigo with cellulitis
B. Mixed Staphylococcus aureus and herpes simplex virus infection
C. Shingles of the V1 dermatome
D. Sporotrichosis
Answer and discussion:
Answer is B. The bacterial culture grew S. aureus (MSSA) and the viral culture grew herpes simplex virus (HSV). Therefore, the answer is B, mixed S. aureus and HSV infection, which explains the unusual appearance. On admission, he was started on IV nafcillin and, on a hunch, IV acyclovir was added and continued when the HSV culture returned positive. Within a couple of days, there was some improvement of the swelling, erythema and pain. The fluid in the lesion did not reaccumulate, but the lesion continued to have an unusual appearance (Figure 3). The patient went home on cephalexin plus oral acyclovir with rapid resolution. It is likely that the baseball cap headband irritated the original lesion, causing some of the unusual appearance.
There’s nothing new about mixed infections, such as varicella and group A strep cellulitis and necrotizing fasciitis (Figure 4); bacterial tracheitis and viral croup; infectious mononucleosis and group A strep tonsillitis, influenza as well as HSV enhancing pneumococcal disease (Figure 5); and others. Animal and human studies have shown the enhanced pathological effect of joint viral and bacterial infections. Nelson and McCracken’s landmark bacterial meningitis studies in the 1980s showed that most cases of bacterial meningitis in children are preceded by a viral upper respiratory infection (URI) an average of 4 days earlier. A Scientific American paper by Gould published on July 21, 2011, reviewed this phenomenon. The development of PCR testing to detect viruses and more sophisticated bacterial culture techniques now has this door wide open for further discovery. Bearing this in mind, if a lesion looks unusual, consider the possibility of a coinfection or an underlying skin disease complicating an infection.
Uncomplicated bullous impetigo and cellulitis may look similar, but the vast majority of cases of bullous impetigo show small, discrete lesions with blisters and are not complicated by cellulitis, and when they are, intact blisters do not last long. These blisters don’t remain intact for long because the epidermolytic toxin causing the formation of the blister damages the very superficial layer of the skin, making a very fragile cover, which usually ruptures at the slightest disturbance.
Shingles may have discrete vesicles in the V1 dermatomal pattern (Figure 6), but it is very unlikely to have a large, irregularly shaped fluid-filled lesion, as shown. At the patient’s age, shingles would be uncommon, especially in a child who had a robust case of varicella as a school-aged child. A child who has a mild case as an infant may be more likely to have shingles later.
Figure 6. Shingles of the V1 dermatome. Source: James H. Brien, DO.
And lastly, sporotrichosis (infection by Sporothrix schenckii) usually presents as a small, chronic erythematous papular lesion that progresses on to ulceration (Figure 7). It is usually inoculated into the skin by a contaminated object, classically a rose thorn. In the early stage, the lesion(s) may be mistaken for HSV, but the persistence should alert the examiner to the possibility of a more chronic problem, such as sporotrichosis.
Columnist comments
This case was originally published in the November 1991 issue of IDC. Since then, the advent and wide availability of PCR testing has made it clear that the long-standing suspicion of coinfections is commonplace. For example, early in my career, as noted earlier, some clinical studies revealed an association of a viral URI and the subsequent development of sepsis and meningitis (Haemophilus influenzae type b), and viral croup and bacterial tracheitis. Our personal experience has added to this observation. PCR has been a significant game-changer in the field of infectious diseases. Organisms previously found to be difficult to grow or requiring a long incubation time can now often be identified in a matter of hours. On the other hand, sensitivity is such that contamination can be problematic. Also, the sensitivity of bacteria may still require culture. But there’s no question that multiple pathogens are often detected in the same illness or lesion of a patient. Also, similar targets may exist in different viruses, such as enterovirus and RSV, making interpretation problematic. With this in mind, when a lesion looks unusual or an illness is not taking the usual path, consider the possibility of a mixed infection.
With springtime upon us, begin anticipating the summertime problems that lie ahead — tetanus-prone injuries, animal bites, insect bites that may carry diseases (arboviruses, tick-born infections), and enteroviruses, with the commonly associated aseptic meningitis, etc. Hopefully, the latest COVID-19 mutation will not cause a summertime surge. It could be a real problem in some cases, distinguishing between an enteroviral infection and COVID-19. Remember to keep your fingers out of your nose, mouth and eyes. Even if COVID-19 is behind us, that advice is timeless.
Reference:
Gould SE. When viruses and bacteria unite! Scientific American. Published July 21, 2011. https://blogs.scientificamerican.com/lab-rat/when-viruses-and-bacteria-unite/. Accessed Feb. 18, 2022.
For more information:
Brien is a member of the Healio Pediatrics 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.