Adult-onset chronic recurrent multifocal osteomyelitis: A case report of a rare entity.

Background: Chronic recurrent multifocal osteomyelitis is a rare autoimmune disorder causing inflammatory joint lesions. It has an estimated prevalence of 1-2 per million while adult-onset disease constitutes only 6.3% of patients.

Case report: We present a case of a 44 years old male who presented to the rheumatology clinic with lower back pain for twelve years. Magnetic resonance imaging of the lumbosacral spine showed ovoid areas of abnormal signal intensities along superior and inferior endplates of multiple vertebrae of the dorsolumbar and sacral spine. Computed tomography guided biopsy of L4 vertebrae was done. Histopathology revealed linear cores of degenerating fibrocartilage focally exhibiting small spicules of mineralized bone and fibro-collagenous tissue. He initially did not respond to traditional therapy. His symptoms improved with the addition of a Janus Kinase inhibitor. To the best of our knowledge, this is the first case of chronic recurrent multifocal osteomyelitis to be reported from Pakistan.