The usefulness of infraorbital nerve enlargement on MRI imaging in clinical diagnosis of IgG4-related orbital disease

Abstract

To investigate the frequency of infraorbital nerve enlargement (IONE) in orbital lymphoproliferative disorders, and to show that IONE can contribute to the clinical diagnosis of IgG4-related orbital diseases (IgG4-ROD). 71 cases in which orbital lymphoproliferative disorders were diagnosed at Okayama Medical Center and Mitoyo General Hospital from April, 2004 to March, 2011 were investigated. The male-to-female ratio was 39:32, and the age range 27-87 years old (average age 64.1 years). Whenever the coronal section of the infraorbital nerve was larger than that of the optic nerve on MRI, it was defined as IONE. The breakdown of the 71 cases was: 45 cases of non-Hodgkin lymphoma, 16 cases of IgG4-ROD, 5 cases of reactive lymphoid hyperplasia, and 5 cases of idiopathic orbital inflammation. Of these, a total of 9 cases had IONE. The incidence of IONE was compared between the IgG4-ROD patient group and the non-IgG4-ROD patient group and was significantly higher in the IgG4-ROD patient group (p < 0.0001). If IONE is observed in a case of orbital lymphoproliferative disorders on MRI, then it is highly possible that such a case is IgG4-ROD.