The cause of this boy’s swollen lips was unsealed based on critical histopathology.

The 10-year-old presented to a hospital in Okayama, Japan, with persistent painless swelling that was more pronounced on his upper lip.

The doctors noted angular cheilitis with erosions (pictured) and an absence of erythema or tongue plicata.

The boy reported no history of allergy, fever, trauma or gastrointestinal symptoms, with normal blood test results, negative FOBT results and negative micro-organism and mycobacterial tests.