Presentation
Proptosis of the left eye
Patient Data
The left superior rectus muscle is thickened and heterogenously enhancing. The left medial rectus shows less pronounced thickening. Both the muscle belly and tendon insertions are affected.
There is peri-aortic soft tissue thickening extending from below the origin of the renal arteries to the aortic bifurcation with haziness and stranding of the surrounding retroperitoneal fat planes.
Histopathology report of the orbital tissue:
Microscopic examination:
Microscopic examination of the prepared slides revealed fibrofatty tissue with monotonous lymphoid cell infiltration (diffuse positive for CD20). CD3 was scanty positive in the periphery. CD10 was negative. Ki76 was non-conclusive.
Diagnosis: Orbital fibrofatty tissue with scanty monotonous lymphoid tissue of B cell origin. A picture highly suggestive of IgG4-related fibroinflammatory disorder.
Case Discussion
IgG4-related fibroinflammatory disease is a systemic disease of unknown etiology. Orbital affection is manifested by unilateral proptosis caused by diffuse enlargement of the extraocular muscles without sparing the tendon insertions. It should be differentiated from the extraocular muscle thickening due to thyroid eye disease, which shows bilateral affection and sparing of the tendon insertion.
Retroperitoneal fibrosis is also one of the components of IgG4-related fibroinflammatory conditions. It usually manifests as ill-defined peri-aortic thickening that extends from the level of the renal arteries to the aortic bifurcation and extends to encase the ureters. This is a case of a patient diagnosed with IgG4-related systemic disease affecting both the orbit and the retroperitoneum. The diagnosis was confirmed by histopathology (mentioned earlier).