Mysterious Stomach Rash Had Unusual Source

When a child presented to the emergency department with a brown, lace-like rash on his abdomen, it took a few weeks before physicians pinpointed the likely source.

Initially, they thought it might be bruising from some kind of traumatic injury. However, blood tests and abdominal imaging were clear, and he was sent home.

Yet the patient returned after 2 weeks with progression of the rash and increasing tenderness.

This time, they considered a diagnosis of erythema ab igne (EAI), a reticulated, erythematous rash caused by repeated exposure to low-grade heat, below the level that would cause thermal burns, reported Mara Znagoveanu, MBChB, and Edward Artley, MBChB, both of the University Hospitals of Leicester NHS Trust in England, in BMJ Case Reports.

The main clue was the progression and characteristic reticulated appearance of the rash on that second visit, Znagoveanu told MedPage Today. A more targeted history turned up the fact that the patient was home-schooled, and often balanced his laptop on his abdomen for up to 8 hours a day, including while the laptop was charging.

“I think the main message is to ask specifically about prolonged heat exposure when faced with an unusual reticulated rash, particularly in children,” she said.

Laptops and other electronic devices are increasingly common sources of prolonged low-grade heat, she added, but may not immediately be considered as contributing factors.

“Recognizing the condition early can avoid misdiagnosis and unnecessary investigations, and management is usually simply removal of the heat source,” she said.

EAI is caused by repeated exposure to low-grade heat from devices like heating pads or hot water bottles. Laptop-induced EAI is well-recognized in adults, usually affecting the thighs.

However, it’s not frequently reported in children — though there was an increase in published reports of pediatric EAI linked to remote learning and prolonged device use during the COVID-19 pandemic, the authors noted.

Unique to this case was that the rash was on the abdomen, and when the child first presented to the emergency department, the nursing team triaged him as having “spontaneous bruising,” suggesting traumatic injury. The skin changes appeared on the upper right quadrant of his abdomen, were non-tender, and had been there about a week, the authors wrote. Neither the patient nor his parents could identify a cause.

The authors described the lesion as having a “distinct pattern, with interlacing lines forming irregular circles and a lace-like morphology. The borders were ill-defined and faded into the surrounding skin.”

During a blood draw, the child disclosed that he and his sibling had been play-fighting about a week earlier, and he’d been pushed into a chair. He hadn’t told his parents for fear the sibling would get into trouble, he said. He was sent for CT imaging of his abdomen, but there was no evidence of traumatic injury.

Given the otherwise normal findings, “the patient was discharged with a 5-day course of Co-amoxiclav and safety-netting device,” they write.

However, he was back after about 2 weeks with progression of the rash, and increasing tenderness. The brown patch was larger, there was increased erythema, and pink patches suggested skin breakdown — changes that “prompted reconsideration of the initial diagnosis of bruising,” they wrote.

Although initial inquiries about possible exposure to heat sources were negative, further questioning revealed that he was home schooled, and could rest his laptop on his abdomen for up to 8 hours a day, leading to the diagnosis of EAI.

EAI is generally benign and reversible, the authors noted. The lesions usually improve over weeks to months after removal of the heat source, although the hyperpigmentation may persist.

In this case, the child was discharged after a dressing was applied and he was counselled against further exposure to the laptop.

“Telephone follow-up with the patient’s father several months later confirmed gradual improvement and complete resolution of the rash after removal of the heat source,” they concluded, noting that the lack of in-person follow-up was a limitation of the case report.