Clinical progression of a smallpox postvaccination response.
Maggie H Zhou, Shari R Lipner, Stephen K Tyring
✦ AI-curated · Sources linked
Case in brief
A 20-year-old man with no significant medical history presented with a shallow, well-circumscribed, non-necrotic ulcer on his shoulder. He had received a smallpox vaccine injection at that site several weeks earlier while preparing to join the military. Although pyoderma gangrenosum, brown recluse bite, and Buruli ulcer were considered, the lesion was consistent with the expected localized postvaccination response, which is self-limited.
What made this case unusual
The ulcer’s appearance raised a differential that included several unrelated conditions, but its location at the recent vaccination site and the characteristic progression supported a benign vaccine response.
Diagnostic / clinical pearl
For an isolated ulcer at a prior smallpox vaccination site, vaccination history and the expected local progression can support the diagnosis. Systemic symptoms, nonhealing ulcers, or generalized skin involvement suggest a rare vaccine-related complication rather than the usual localized response.
Why it matters
Recognizing this response may help dermatologists avoid misdiagnosis and unnecessary workup in military recruits and healthcare workers who receive smallpox vaccination.