A mass squeezing a young woman's spinal cord shrank so quickly on steroids that doctors called off a planned needle biopsy because there was no longer a safe target. More than two months later, a lab culture told a different story: a rare, slow-growing bacterium first identified in Saudi Arabia caused the mass.
Physicians at King Abdulaziz Medical City and other institutions in Riyadh reported the case, which was published in Case Reports in Infectious Diseases on May 26, 2026. It describes a 29-year-old Saudi woman whose infection with Mycobacterium riyadhense was first treated as neurosarcoidosis, an inflammatory disease, with steroids and the immune-suppressing drug rituximab.
