Coexisting Sacroiliac Arthritis and Chronic Nonbacterial Osteomyelitis in an Adolescent with Ehlers-Danlos Syndrome: A Case Report and Treatment Success.

BACKGROUND Chronic nonbacterial osteomyelitis (CNO) is a multifocal autoinflammatory bone disease mainly affecting children and adolescents. Sacroiliitis is an inflammation of the sacroiliac joint, diagnosed with the use of musculoskeletal MRI due to its ability to visualize active inflammatory lesions. Ehlers-Danlos syndrome (EDS) is non-inflammatory hereditary disorder of connective tissue. Here, we report the case of a 17.5-year-old female patient with classical EDS and long-term course of the CNO with coexistence of sacroiliac arthritis. CASE REPORT On admission, a patient with CNO reported pain in the scapula, thoracic spine, shoulders, and iliac region, with morning stiffness present for 5 months. Physical examination revealed knee and elbow joint hyperextension, hypermobility of the phalanges, increased range of motion of the hip joints, and the presence of reticular rash on the face. In the laboratory blood tests, minor leukocytosis was reported. During hospitalization, a whole-body MRI was performed, detecting bone marrow edema in the Th3, Th4, and Th7 vertebral bodies and the head of seventh rib on the left side, as well as bilaterally in the sacroiliac joints. The patient was diagnosed with sacroiliitis and EDS and successfully treated with risedronate sodium, methotrexate with folic acid, sulfasalazine, and meloxicam, achieving CNO remission and reduced severity of axial skeleton pain. CONCLUSIONS The coexistence of these 3 diseases - CNO, sacroiliac arthritis, and EDS - in the same patient is rare and requires interphysician collaboration to determine the correct diagnosis and subsequently arrange multi-speciality therapeutic management to achieve remission.