Enlargement of the infraorbital nerve: an important sign associated with orbital reactive lymphoid hyperplasia or immunoglobulin g4-related disease.

Objective: To describe the clinical, histopathologic, and radiologic features of a recently identified cause for enlargement of the infraorbital canal.

Design: Retrospective, noncomparative case series.

Participants: Consecutive patients were identified from the orbital databases at Moorfields Eye Hospital, London, England, and the Royal Victorian Eye and Ear Hospital, Melbourne, Australia.

Methods: A retrospective, noncomparative review of the clinical case notes, radiology, and histopathology was performed. The English-language medical literature was reviewed for reports of enlargement of the infraorbital canal or nerve.

Main Outcome Measures: Extent of clinical and radiologic changes in patients with enlargement of the infraorbital canal.

Results: A total of 14 patients (10 male) presented between the ages of 29 and 76 years with proptosis, eyelid swelling or a mass (10/14 cases), and periocular ache (5/14 cases). Clinical evidence of bilateral involvement was present in 6 of 14 patients. None had impairment of visual functions or facial sensation, but 4 of 14 patients had some reduction in ocular motility. Imaging showed a focal orbital mass in 10 of 14 patients (16/28 orbits), and all patients (22/28 orbits) had enlargement of some extraocular muscles. The infraorbital canal was enlarged in 20 of the 28 orbits, with associated ipsilateral orbital changes in 19 of 20 (all 14 patients) and ipsilateral maxillary sinus changes in 12 of 20 (11 patients). Biopsy-proven chronic orbital inflammation was present in all patients; this resembled reactive lymphoid hyperplasia (RLH) in 7 patients and immunoglobulin (Ig) G4-related sclerosing inflammation in 7 patients. When tested, serum IgG4 was elevated in 6 of 7 patients. Clinical or histologically proven enlargement of cervical lymph nodes was present in 7 of 14 patients. All patients responded well to systemic corticosteroid therapy, although some had a relapse upon withdrawal. One patient developed diffuse large B-cell lymphoma and subsequently leukemia, of which he later died 20 years after presentation.

Conclusions: Enlargement of the infraorbital nerve and canal is rare and strongly suggests a diagnosis of RLH or IgG4-related disease, especially in the presence of ipsilateral extraocular muscle enlargement, sinus disease, or focal orbital disease.