A teenage boy developed painless "penile erosions" while infected with the coronavirus, a case report has revealed.
The unnamed 17-year-old arrived at Boston Children's Hospital's emergency department after enduring the erosions and mouth ulcers for three days.
He had tested positive for the virus a week earlier after developing the tell-tale loss of taste and smell, which "spontaneously resolved".
A physical examination in hospital revealed the teen had painful "shallow erosions" on the curves of his upper lip and hard palate, as well as red lesions on the tip of his penis.
The teen was initially treated with a steroid ointment and oral solution, as well as paracetamol and ibuprofen, but his mouth pain worsened over the next three days.
Medics therefore administered a different oral steroid that led to a "drastic improvement".
Tests revealed the patient had a normal breathing rate and blood-oxygen level.
The teen, who was "in no distress", also had five small fluid-filled blisters on his trunk and arms.
Blood tests revealed his immune cell counts were normal. More severe coronavirus symptoms can sometimes occur if the immune system overreacts to the infection.
His C-reactive protein levels, a marker of inflammation, were only "slightly elevated", the medics wrote in the journal Jama Dermatology.
The teen tested positive for the coronavirus again, while also swabbing negative for other infections like flu and pathogens that cause pneumonia.
He was diagnosed with "SARS-CoV-2 [coronavirus]–associated reactive infectious mucocutaneous eruption (RIME)".
The teenager was initially given the steroid betamethasone valerate as an ointment for his lips and penis, as well as dexamethasone as an oral solution. The NHS routinely administers the latter drug to critically ill coronavirus patients.
When the patient's mouth pain progressively worsened, the medics administered the steroid prednisone as an oral solution every day for four days. "This was followed by drastic improvement in his mucositis"; when the mouth is inflamed or sore.
The mucositis reoccurred three months later, but resolved with six days of prednisone.
Watch: Do coronavirus vaccines affect fertility?
The medics concluded the coronavirus was likely the "infectious trigger" for the teen's symptoms.
Few skin symptoms or "dusky targetoid lesions" – blemishes with concentric zones that may not be triggered by an infection – also distinguished the case from Stevens-Johnson syndrome.
Stevens-Johnson syndrome, a rare but serious skin and mucous membrane disorder, has been linked to the coronavirus in severe cases.
The teenager also did not appear to have the somewhat mysterious multi-system inflammatory syndrome that has arisen in some children with the coronavirus.
The inflammatory syndrome has been likened to Kawasaki disease, a rare condition that usually affects children under five and causes blood vessels to become inflamed, leading to heart complications in around a quarter (25%) of patients. Left untreated, it can be fatal in 2% to 3% of cases.
The inflammation tends to involve the skin, mucus membranes – like the mouth and eyelids, and inner organs, as well as causing "dramatically elevated systemic inflammatory markers".
Speaking of the teenage patient, the medics wrote: "This case highlights what is to our knowledge the first report of SARS-CoV-2–induced RIME."
Skin symptoms like rashes, chilblains and hives are relatively common among coronavirus patients, however.
Watch: Can you catch the coronavirus twice?