The International Study Group criteria (1990)10
| Criteria | Features |
|---|---|
| Recurrent oral ulcerations | Minor aphthous, major aphthous or herpetiform ulceration observed by physician or patient, which recurred at least three times in one 12-month period |
| Plus any two of the following: | |
| Recurrent genital ulceration | Aphthous ulceration or scarring observed by physician or patient |
| Eye lesion | Anterior uveitis, posterior uveitis or cells in vitreous on slit lamp examination or retinal vasculitis observed by ophthalmologist |
| Skin lesions | Erythema nodosum observed by physician or patient, pseudofolliculitis or papulopustular lesions, or acneiform nodules observed by physician |
| Positive pathergy test | Read by a physician at 24–48 hours. |