Non-specific Orbital Inflammation of Sinonasal Origin

<b>Introduction:</b> Non-specific orbital inflammation (NSOI), or orbital pseudotumor, is the third most common orbital disease, yet its pathogenesis remains poorly understood. A dysregulated immune response to infections or trauma, including surgery, has been proposed as a contributing factor. However, reports of NSOI coexisting with sinusitis are scarce and mostly limited to isolated case reports.<b>Aim:</b> This study examines a subset of NSOI patients with coexisting chronic rhinosinusitis with nasal polyps (CRSwNP), aiming to explore potential pathophysiological links and evaluate treatment outcomes.<b>Materials and methods:</b> Between 2014 and 2024, 34 patients with NSOI were assessed at the Medical University of Bialystok. In 7 cases (20%), NSOI was associated with CRSwNP. Diagnosis was confirmed through orbital tissue biopsy and exclusion of systemic diseases.<b>Results:</b> Orbital symptoms - diplopia, proptosis, and pain - developed after sinonasal symptoms and surgical intervention in all cases. Early bacteriological cultures showed various pathogens, but intraoperative cultures during remission were sterile. Tissue or blood eosinophilia, along with recurrent exacerbations and signs of bacterial infection, suggested a mixed type 2/type 3 inflammatory endotype. Imaging revealed orbital wall defects with new bone formation (osteogenesis), and histopathology showed marked fibrosis. Treatment with corticosteroids led to partial stabilization in four patients; two required immunosuppressants and two underwent radiotherapy. None achieved complete remission.<b>Conclusions:</b> These findings suggest that chronic rhinosinusitis may trigger or worsen NSOI in susceptible individuals, particularly those with underlying immune dysregulation. Standard treatments are often ineffective in advanced fibrotic stages, highlighting the need for tailored, multidisciplinary approaches and further research into the underlying mechanisms.