Scary scan When doctors describe your brain scan as a “starry sky,” it’s not good TB is the deadliest infection in the world—but it doesn't often look like this. Beth Mole – May 9, 2025 5:40 pm | 7 Credit: Getty Images Credit: Getty Images Story text Size Small Standard Large Width * Standard Wide Links Standard Orange * Subscribers only   Learn more A starry sky can be stunning—even inside a hospital emergency room. But instead of celestial bodies sparkling in the night, doctors in South Korea were gazing at bright brain lesions punctuating a magnetic resonance imaging (MRI) scan. The resulting pattern, called a "starry sky," meant that their 57-year-old patient had a dangerous form of tuberculosis. The doctors report the case in this week's issue of the New England Journal of Medicine. The man had previously been treated for the infection in his lungs but came into the hospital's emergency department after two weeks of unexplained headaches, neck pain, and tingling in his right hand. The MRI and Computed-Tomography (CT) scans clearly revealed the problem: rare nodules and lesions, called tuberculomas, speckling his lungs and central nervous system, including both cerebral hemispheres, the basal ganglia deep inside the brain, the cerebellum at the back of the brain, the brain stem, and the upper spinal cord. Magnetic resonance imaging (MRI) of the head with gadolinium enhancement revealed numerous small, spherical, peripherally enhancing nodules in the cerebral hemispheres (Panels A and B), basal ganglia, cerebellum, and brain stem, as well as in the upper spinal cord with surrounding edema (Panel C). Credit: NEJM, 2025 The condition, called CNS tuberculoma, is a relatively rare manifestation of tuberculosis, which typically infects the lungs but can invade any part of the body. It's unclear exactly how tuberculomas form, but evidence suggests that the bacteria that cause tuberculosis—Mycobacterium tuberculosis—can spread around the body via the blood. M. tuberculosis can get past the blood-brain barrier, possibly by hiding inside a type of white blood cell called a macrophage, in a "Trojan horse" mechanism or by breaking through the barrier. Tuberculomas are thought to form when bacteria and macrophages clump together into masses that may contain calcifications or cheese-like dead tissue called caseum. With the tuberculomas visualized, the doctors worked to diagnose the man's condition. Generally, the CNS tuberculosis can be notoriously difficult to diagnose, given that M. tuberculosis are slow-growing and stealthy and can produce generic symptoms. The man's cerebrospinal fluid, for instance, was negative for the bacteria. But a sputum sample was positive. Tuberculomas are often seen amid tuberculosis infections that have not been adequately treated. That seems to be the case for the patient here, who had been previously treated for tuberculosis. Sometimes patients with tuberculomas also have tubercular meningitis, brain inflammation from the infection. Fortunately, the man did not develop this even more serious manifestation of the disease. With an intensive course of anti-tuberculosis antibiotics and an anti-inflammatory drug, the man's symptoms gradually began to ease. After a month, he was feeling better. After 18 months, his symptoms had completely resolved, and a repeat MRI of his head was normal. Tuberculosis is the leading infectious disease killer globally. In 2023, the bacteria infected 10.8 million people and killed 1.25 million. The World Health Organization estimates that about a quarter of the world's population has been infected with M. tuberculosis, which spreads through the air. Beth Mole Senior Health Reporter Beth Mole Senior Health Reporter Beth is Ars Technica’s Senior Health Reporter. Beth has a Ph.D. in microbiology from the University of North Carolina at Chapel Hill and attended the Science Communication program at the University of California, Santa Cruz. She specializes in covering infectious diseases, public health, and microbes. 7 Comments