Syphilitic hepatitis mimicking autoimmune liver disease: a case report and review of the literature

The liver is a tireless internal filter, constantly processing nutrients and neutralizing toxins. When it becomes inflamed, the body sends out distress signals, often in the form of jaundice, where the skin and eyes turn yellow, or intense itching. Sometimes, the immune system mistakenly attacks the liver, a condition doctors call autoimmune liver disease. In these cases, the body's own defense cells turn against healthy tissue, and blood tests reveal specific markers that act like a fingerprint for this self-destruction. Because these markers are so reliable, doctors often trust them to guide treatment, which usually involves powerful drugs that calm the immune system down. However, nature is full of clever disguises. A different kind of trouble, caused by a bacterial infection known as syphilis, can sometimes wear the same uniform as an autoimmune attack. This creates a dangerous trap: if a doctor mistakes an infection for an autoimmune disease, they might give the patient immune-suppressing drugs that could allow the infection to spread unchecked.

A team of researchers at the National Hospital of Sri Lanka recently documented a striking example of this deception in a 47-year-old woman. She arrived at the hospital after fainting, followed by a high fever and a rapid decline in her health. Her skin turned deeply yellow, her urine became dark, and she suffered from relentless itching. Her medical history included diabetes and high blood pressure, but she had no history of alcohol use or drug exposure. As doctors investigated, they found her liver was struggling to process bile, a fluid that helps digest fats. Her blood tests showed a specific pattern of injury where the enzymes responsible for moving bile were sky-high, while other liver enzymes were only moderately elevated. This pattern, known as cholestasis, pointed toward a blockage or a specific type of liver inflammation.

The situation became more confusing when the doctors looked at her immune system. Her blood contained high levels of antibodies that typically signal an autoimmune attack on the liver. Specifically, she had a positive test for antimitochondrial antibodies, which are strongly associated with a chronic liver condition called primary biliary cholangitis, and she also had a positive test for antinuclear antibodies, often seen in autoimmune hepatitis. Her total level of immunoglobulin G, a type of protein made by the immune system, was also elevated. Taken together, these results painted a picture of a woman suffering from a complex overlap of two autoimmune liver diseases. The standard medical response would have been to start her on corticosteroids to suppress her immune system.

However, the medical team paused to look closer at the whole picture. During a detailed review of her history, she mentioned a rash that had appeared on her palms and soles about a month earlier, which she had not found itchy. She also recalled a period of unprotected sexual contact a few months before her illness. These details, combined with her fever and joint pain, raised a different suspicion: secondary syphilis. Syphilis is a bacterial infection that is famous for mimicking many other diseases, earning it the nickname "the great imitator." To test this theory, the doctors ordered a specific test for the bacteria that causes syphilis. The result was definitive: her blood showed a very strong reaction to the syphilis bacteria, confirming an active infection.

A small sample of her liver tissue, taken through a needle biopsy, provided further clarity. Under the microscope, the tissue showed inflammation centered around the bile ducts, with a mix of immune cells that included plasma cells. While plasma cells are often seen in autoimmune diseases, the overall pattern lacked the specific, destructive damage that characterizes the autoimmune conditions her blood tests had suggested. The inflammation looked more like a reaction to an invader than a self-directed attack. The doctors then treated her with a standard course of antibiotics designed to kill the syphilis bacteria, specifically benzathine penicillin. They did not give her any steroids or immune-suppressing drugs.

The outcome was decisive. Within weeks, her fever vanished, the itching stopped, and her skin color returned to normal. Her liver function tests, which had been severely abnormal, dropped back to healthy levels. Most importantly, the "autoimmune" markers in her blood disappeared. The antibodies that had pointed toward a lifelong autoimmune disease were no longer detectable, and her immunoglobulin levels returned to normal. The syphilis test, which had been extremely high, dropped significantly, confirming the infection was clearing. The researchers concluded that the woman had never had an autoimmune liver disease at all. Instead, her body's reaction to the syphilis infection had temporarily created a perfect copy of the disease, including the blood markers and the tissue appearance.

This case serves as a vital reminder for medical practitioners that not every positive test for an autoimmune condition means the patient has one. When a patient presents with liver inflammation, especially if they have a rash on their hands or feet, a fever, or a history of recent sexual exposure, doctors must consider infectious causes before committing to a diagnosis of autoimmune disease. The researchers found that the body can produce these confusing markers simply because it is fighting a severe infection. If the patient had been treated with steroids for a disease they did not have, the infection could have worsened. By waiting to see how the patient responded to antibiotics and by re-evaluating the blood tests over time, the medical team avoided a potentially harmful mistake. The study highlights that while blood tests are powerful tools, they must always be interpreted within the full context of the patient's story and physical symptoms. In this instance, the infection was the true cause, and once it was treated, the illusion of autoimmune disease vanished.