Strange marks, no pain

A boy in mid-childhood arrived at a UK emergency department with a six-inch patch on his abdomen: flat, reddish-brown lines forming irregular circles. It didn't hurt and wasn't warm.

“interlacing lines forming irregular circles and a lace-like morphology”

Nothing else looked wrong

No fever, no fatigue, no tenderness, no recent illness. Growth and medical history were normal. Nurses wrote it off as spontaneous bruising, and the physical exam turned up nothing.

A chest X-ray muddies it

Searching for any explanation, doctors imaged his chest and found a small patch of whiteness over the left lung, a sign of fluid or cells like pus or blood.

The injury he hid

While blood was being drawn, the boy admitted he'd been pushed into a chair during play-fighting about a week earlier. He'd stayed quiet because he didn't want his siblings in trouble.

A CT scan finds nothing

Doctors scanned for internal abdominal damage and came up empty. They sent him home on antibiotics for the lung spot, telling his parents to return if the marks stuck around.

Eight hours a day of heat

Two weeks later the marks were bigger, darker, tender, and breaking down. Then he mentioned he was homeschooled and rested his charging laptop on his abdomen for up to eight hours a day.

Toasted skin syndrome

The diagnosis was erythema ab igne, Latin for redness from fire, caused by repeated low-grade heat that never burns. Remove the heat and it usually fades. His cleared up completely.

“researchers hypothesize that chronic heat exposure leads to damage to superficial blood vessels”