A man in his 50s struck his chest against a brick wall in a car crash. He reported chest pain and a general feeling of illness, and weeks later he went into cardiac arrest in the hospital and could not be revived.
At autopsy, pathologists found that his aorta, the body's main artery, had ruptured. Its inner lining also had a bumpy, irregular, wrinkled texture that pathologists have long compared to tree bark, a pattern classically tied to an infection most people never connect with the heart: untreated syphilis.
The case is described in an abstract titled "Barking up an unusual tree" published in Pathology, the journal of the Royal College of Pathologists of Australasia. The authors concluded that the findings were most suggestive of syphilitic aortitis, a rare late complication of the disease.
What the Autopsy Revealed
The man's known history was limited. According to the abstract, it included illicit drug use and immigration to Australia from Asia more than 20 years earlier.
The autopsy found an aneurysm, or abnormal bulge, in the arch of the aorta, with a rupture point sealed by a blood clot, along with 3 liters of blood in the left side of his chest. He also had an extensive type B aortic dissection, a tear that lets blood force its way between the layers of the aortic wall, in this type, affecting the descending aorta.
The outer layer of the aorta was markedly thickened, and the inner lining showed the bumpy wrinkling that gives the tree-bark pattern its name. Under the microscope, the pathologists found ulcerated calcium deposits in the lining, fragmented elastic fibers, inflammation that narrows small arteries, and scarring of the outer wall.
The abstract describes these features as hallmarks of aortitis and most suggestive of syphilis, not as a confirmed diagnosis. It does not describe laboratory confirmation of syphilis, and it does not spell out how much the crash itself contributed to his death.
Why Syphilis Can Leave an Aorta Looking Like Bark
Aortitis, or inflammation of the aorta, is uncommon. The authors note that it can occur with Takayasu's arteritis, tuberculosis, tertiary syphilis, and certain bacterial or fungal infections, and that it can lead to narrowing, aneurysm, dissection, and rupture. The tree-bark appearance, they write, generally refers to syphilitic aortitis specifically.
A decades-old specimen in the CDC's public image library shows the same effect, which the agency describes as markedly irregular wrinkling of the aorta's inner lining in cardiovascular tertiary syphilis.
Tertiary syphilis is the late stage of an infection that was never adequately treated. In its laboratory recommendations for syphilis testing, the CDC calls it a rare condition whose cardiovascular form can produce aneurysms or narrowing as syphilis bacteria multiply in the thoracic aorta or coronary arteries. The gap between the secondary and tertiary stages can last years or decades, and in up to two-thirds of patients, the infection stays latent for life and never progresses.
A Rare Complication Amid Stubbornly High Syphilis Numbers
The case comes from Australia, but it carries weight in the United States, where syphilis climbed for years.
The CDC's most recent national figures, provisional 2024 data from its national STI surveillance report, released in September 2025, show some progress: primary and secondary syphilis, the most infectious stages, fell 22% from 2023 and declined for a second straight year. But congenital syphilis rose for the 12th consecutive year, with nearly 4,000 cases, and is nearly 700% higher than a decade earlier. Reported cases of late syphilis or syphilis of unknown duration more than doubled between 2020 and 2024, from about 47,000 to about 97,000.
Treatment supply is another pressure point. The CDC's syphilis treatment guidance notes that on March 6, 2026, the FDA allowed temporary importation of Lentocilin because of the ongoing limited availability of Bicillin L-A, the long-acting penicillin injection used to treat syphilis. The CDC has urged jurisdictions to preserve the drug for pregnant patients, and recent state health department updates project that Bicillin L-A supply will not fully recover until late 2027.
A Rare Finding with a Simple Takeaway
This is a single autopsy case described in a brief abstract, and it should not be read as evidence that syphilitic aortitis is becoming common. The diagnosis rests on the tissue's appearance and microscopic features, which the authors describe as most suggestive of syphilis.
The authors present it as an unusual cause to keep in mind when evaluating aortic aneurysms and dissections.
For the public, the practical lesson is familiar. Syphilis is diagnosed with blood tests and treated with penicillin, and treatment is meant to clear the infection and prevent the long-term damage that can reach the heart, brain, and blood vessels. People who may have been exposed should talk with a clinician about testing. Anyone with chest pain after trauma, or sudden severe chest or back pain, should seek emergency care.
Key Questions Answered
What is a tree-bark aorta?
It describes an aorta whose inner lining is wrinkled and ridged like bark, a pattern classically associated with syphilitic aortitis.
What happened to the man in this case?
After striking his chest in a car crash, a man in his 50s had chest pain and, weeks later, a fatal cardiac arrest in the hospital. Autopsy showed a ruptured aortic arch aneurysm and an extensive type B dissection.
Was syphilis confirmed?
No. The authors describe the findings as most suggestive of syphilitic aortitis, and the abstract does not report laboratory confirmation.
How does syphilis damage the aorta?
Untreated syphilis can progress over years or decades to tertiary disease, which may affect the thoracic aorta and cause aneurysms or narrowing. Most untreated infections never reach this stage.
Can syphilis be stopped before it reaches this stage?
Yes. Syphilis can be detected with blood tests and treated with penicillin, and treatment helps prevent late complications.
