IgG4-related disease is a recently proposed clinical entity with several unique clinicopathological features. Ocular adnexal IgG4-related disease, however, has not well been clarified. The purpose of the present study was to examine 21 patients (10 men, 11 women; age range, 39-86 years) with ocular adnexal IgG4-related disease. In 17 out of 21 patients (81%), the lacrimal glands were involved and bilateral lacrimal gland swelling was frequently observed (n = 12; 70.6%). In contrast, the conjunctiva was not involved in any of the patient. Histology was uniform with marked lymphoplasmacytic infiltration admixed with dense fibrosis, similar to previous reports of IgG4-related disease. Immunostaining detected numerous aggregates of IgG4-positive plasma cells. Serum IgG4 was higher than normal in 10 of the 13 patients tested, although it was measured after treatment in almost all cases. Interestingly, immunoglobulin heavy chain gene rearrangement was detected in two of 17 patients (12%) examined. The present results show that ocular adnexal IgG4-related disease has uniform clinicopathology: that is, disease involving the bilateral lacrimal glands with lymphoid hyperplasia and fibrosis, but not the conjunctiva. And presence of immunoglobulin heavy chain gene rearrangement suggests the possibility of B-cell lymphoma arising in a background of IgG4-related chronic inflammation. 2 Additionally, AIP has been described in association with other autoimmune disorders, such as chronic sclerosing sialadenitis (Küttner's tumor), sclerosing cholangitis and retroperitoneal fibrosis. 3-15IgG4-related disease is a recently proposed clinical entity and it has several unique clinical findings, but its pathogenesis and pathophysiology remain unclear.3-9 And ocular adnexal IgG4-related disease is either not mentioned or only briefly alluded to in previous reports. 6,[10][11][12] In the present study we examined ocular adnexal IgG4-related disease in detail, with specific reference to clinicopathological features. MATERIALS AND METHODS Patients and materialsWe reviewed the cases of 112 patients (orbital lesions, n = 78; conjunctival lesions, n = 34) with ocular adnexal lymphoproliferative disorders diagnosed between 1990 and 2006. All cases were retrieved from the files of the Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. Histology and immunohistochemistrySurgically resected or biopsied specimens of ocular adnexal lymphoid disorders were fixed in 10% formaldehyde and embedded in paraffin. Serial sections (4 mm) were cut from

IgG4-related disease is a recently proposed clinical entity with several unique clinicopathological features. A chronic inflammatory state with marked fibrosis, which can often be mistaken for malignancy, especially by clinical imaging analyses, unifies these features. In the present report, we describe a case of IgG4-producing mucosa-associated lymphoid tissue lymphoma mimicking IgG4-related disease. The patient was a 55-year-old male who was being followed for right orbital tumor over 1.5 years. The lesion had recently increased in size, so a biopsy was performed. Histologically, the lesion was consistent with IgG4-related disease ; however, IgG4⁺ plasma cells showed immunoglobulin light-chain restriction and immunoglobulin heavy chain gene rearrangement was detected in the lesion. Therefore, the lesion was diagnosed as IgG4-producing mucosa-associated lymphoid tissue lymphoma. In conclusion, in histological diagnosis of IgG4-related disease, it is important to examine not only IgG4-immunostain but also immunoglobulin light-chain restriction.

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.