Clinical Images: Chronic nonbacterial osteomyelitis associated with inflammatory bowel disease

The patient, a 19-year-old man, presented with persistent anterior chest pain. The patient had a history of acne treated with isotretinoin six months before. Admission laboratory tests revealed an elevated erythrocyte sedimentation rate of 30 mm/h (normal range 1–15 mm/h) and a high-sensitivity C-reactive protein level of 11.2 mg/L (normal range 0–6 mg/L). HLA-B51, HLA-B27, antinuclear antibody, antineutrophil cytoplasmic antibodies, rheumatoid factor, and anti–cyclic citrullinated peptide antibody were all negative. A positron emission tomography–computed tomography (PET-CT) scan demonstrated increased fluorodeoxyglucose (FDG) uptake at the bilateral costochondral junctions (maximum standardized uptake value [SUV max] = 11.3) (Figure 1A). Osteolytic changes at the sternal angle were observed with markedly increased FDG metabolism (SUV max = 15.58) (Figure 1B). Hypertrophy of the right L5 transverse process with corresponding pseudarthrosis formation was noted, alongside diffusely increased FDG uptake in the axial skeleton (SUV max = 6.2). There was also focally increased FDG uptake in the sacroiliac joints (SUV max = 6.91). Furthermore, the scan revealed wall thickening and edema of the colon with increased FDG uptake and surrounding exudative changes (SUV max = 4.37) (Figure 1C). Colonoscopy showed diffusely congested, edematous, and eroded colonic mucosa (Figure 1D). Biopsy of the colonic mucosa revealed extensive plasma cell infiltration in the submucosa (Figure 1E). The patient was ultimately diagnosed with chronic nonbacterial osteomyelitis (CNO) and inflammatory bowel disease (IBD). This case underscores two key aspects of adult CNO. First, it highlights that CNO can be part of a broader autoinflammatory syndrome, in which IBD represents a potentially overlooked extraskeletal manifestation.1 Second, it demonstrates the superior use of PET-CT as a “one-stop-shop” imaging modality, enabling simultaneous detection of both osteoarticular and occult visceral inflammation.2 This comprehensive evaluation is crucial for accurate disease staging and monitoring in complex cases with systemic involvement. This study was approved by the Ethics Committee of Sir Run Run Shaw Hospital of Zhejiang University School of Medicine. Disclosure form. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.