Guidelines for the standardized diagnosis and treatment of non-specific orbital inflammation (2024)

Abstract

Non-specific orbital inflammation (NSOI) is a non-infectious orbital inflammation. Although it is often considered the most common diagnosis in orbital biopsies, it is an exclusionary diagnosis that requires ruling out systemic disease or other possible causes. Its characteristics include acute orbital signs and symptoms, including pain, proptosis, periorbital edema, chemosis, diplopia, and visual impairment. The clinical manifestations and histological findings of NSOI are heterogeneous, without specific diagnostic criteria or treatment guidelines, which poses significant challenges for diagnosis and treatment. This guideline provides a detailed description of the definition, classification, diagnosis, and treatment of NSOI.

Keywords: clinical manifestation; diagnosis; non-specific orbital inflammation; treatment.

Figure 1. CT and MRI images of different subtypes of pathologically confirmed NSOI

A, B, C: MRI (diffuse enlargement of the lacrimal gland, isotropic T1 and short T2 signals, well-defined fat suppression borders, prominent enhancement on enhancement imaging, neighboring extraocular muscles can be involved or displaced) and CT images (amygdaloid enlargement of the lacrimal gland with homogeneous increase in density, partial infiltration of the surrounding tissues, and absence of bone destruction) of lacrimal gland type NSOI. D, E: MRI (thickening of the tendon and muscle belly of the lesion muscle, isotropic T1, short T2 signal, moderate enhancement on enhancement imaging) and CT images (thickening of the tendon and muscle belly at the same time, blurred borders, and no bony destruction) of the myotropic type of NSOI. F, G: CT images of the diffuse type of NSOI (the lesion is more extensive, characterized by thickening of the extraocular muscles, lack of clear demarcation of the extraocular muscles from the lesion, enlarging of the lacrimal gland, thickening of the ocular ring, and enlargement of the optic nerve. The ocular ring exhibits thickening, potentially encircling the optic nerve, which demonstrates enhancement without affecting the optic nerve. Typically, intraorbital low-density fat shadow is replaced by soft tissue density shadow. H, I: MRI images of posterior (orbital apical) NSOI (isometric TI signal, long T2 signal, moderate-significant enhancement on enhancement scan. J, K, L: Images of bone-destroying type NSOI (CT and MRI: soft tissue density shadow visible in the orbital septum, with a relatively homogeneous density, generally without calcification, limited destruction of the orbital bone in the inner and lower walls is missing, and the lesion involves extra-orbital tissues. MRI: Isotropic T1 signal, inhomogeneous short T2 signal. NSOI: Nonspecific orbital inflammation; MRI: Magnetic resonance imaging; CT: Computed tomography.

Figure 2. Pathohistologic changes of NSOI

A: Inflammatory cell infiltration of intraorbital tissues and nerves (arrows), HE ×400; B: Positive staining for CD20 and CD3, IHC ×200; C: Pathologic tissue of vascular NSOI, with dilated blood vessels and inflammatory cell infiltration seen within the orbital fat, HE ×200; D: Large amount of fibrous connective tissue hyperplasia accompanied by inflammatory cell infiltration within the lesion of sclerosing NSOI, HE ×200; E: Amyloidosis pathologic tissue (eosinophilic inflammation), a large amount of amyloid amorphous material is seen to be deposited within the lesion, mostly along the perivascular area, HE ×100; F: Amyloidosis pathologic tissue (eosinophilic inflammation) with positive Congo red staining, Congo red staining ×200. NSOI: Nonspecific orbital inflammation; HE: Hematoxylin-eosin; IHC: Immunohistochemistry.