Dermatologic disorders in 118 patients with autoimmune (immunoglobulin G4-related) pancreatitis: a retrospective cohort analysis

The unique properties of IgG4 and its roles in health and disease

IgG4 is the least abundant subclass of IgG in human serum and has unique functional features. IgG4 is largely unable to activate antibody-dependent immune effector responses and, furthermore, undergoes Fab (fragment antigen binding)-arm exchange, rendering it bispecific for antigen binding and functionally monovalent. These properties of IgG4 have a blocking effect, either on the immune response or on the target protein of IgG4. In this Review, we discuss the unique structural characteristics of IgG4 and how these contribute to its roles in health and disease. We highlight how, depending on the setting, IgG4 responses can be beneficial (for example, in responses to allergens or parasites) or detrimental (for example, in autoimmune diseases, in antitumour responses and in anti-biologic responses). The development of novel models for studying IgG4 (patho)physiology and understanding how IgG4 responses are regulated could offer insights into novel treatment strategies for these IgG4-associated disease settings.

IgG4-related ophthalmic disease in association with adult-onset asthma and periocular xanthogranuloma: a case report

A 54-year-old male presented with a three-year history of bilateral upper eyelid and peri-orbital swelling and adult-onset asthma. Histopathology of a left orbital biopsy showed lymphoid follicles with foamy macrophages and Touton giant cells. Clinical, histological and radiological features were consistent with adult-onset asthma and periocular xanthogranuloma. Treatment with rituximab led to a complete clinical and radiological remission. Nine years later, his condition relapsed with a biopsy of the left orbit and lacrimal gland demonstrating features of IgG4-related disease and adult-onset asthma and periocular xanthogranuloma. Immunohistochemistry showed increased numbers of IgG4+ plasma cells (290 per high power field) and an elevated IgG4+/IgG+ plasma cell ratio of 480%. Involvement by both disorders in the orbit and ocular adnexa of a single patient has not previously been reported in the literature, to the best of our knowledge, and suggests a possible aetiologic or pathophysiologic association.

Systemic IgG4-Related Disease Masquerading as Cholangiocarcinoma: A Case Report Underscoring the Importance of Medical History

BACKGROUND Immunoglobulin (Ig) G4-related disease is a rare disease of unknown pathophysiology, which can affect multiple organs leading to tissue fibrosis and organ failure. The present case report describes a patient with systemic IgG4-related disease (IgG4-RD) that occurred over a 1-year period and affected multiple organs at different times. Imaging studies, interventional procedures, changes in laboratory parameters, and histopathology demonstrate the novel and known aspects of this disease before and during prednisolone monotherapy and in combination with azathioprine. CASE REPORT A 64-year-old man presented with weight loss and painless jaundice, which was highly suspicious for cholangiocarcinoma. A thorough medical history together with laboratory tests, imaging procedures, and endoscopic interventions confirmed that surgery was not needed and led to the final diagnosis of histologically-confirmed, IgG4-related sclerosing cholangitis and autoimmune pancreatitis type 1. Other typical organ manifestations of systemic IgG4-RD were diagnosed through a thorough medical review, which led to immunohistochemical reevaluation of past surgical specimens. Besides the IgG4-related organ manifestations, which can include periorbital xanthelasmas, our patient developed a pulmonary adenocarcinoma 6 years after the initial clinical onset of IgG4-RD. After immunosuppressive treatment with prednisolone alone and subsequently in combination with azathioprine, the patient's IgG4-RD resolved. CONCLUSIONS Interdisciplinary collaboration is required to diagnose IgG4-RD that involves multiple organs. Patient medical history remains crucial for diagnosis and attention should be paid to avoiding unnecessary surgery. Tumors (lung adenocarcinomas) and xanthelasmas can develop because of IgG4-RD. Glucocorticoids and additional azathioprine may be advisable for maintenance treatment.

Successful treatment with rituximab of IgG4-related disease coexisting with adult-onset asthma and periocular xanthogranuloma

Immunoglobulin G4-related disease (IgG4RD) is a systemic fibro-inflammatory disease of unknown aetiology, which is characterized by tumefactive lymphoplasmatocytic infiltrative lesions, with a predominance of IgG4 positive plasma cells, fibrosis and obliterative phlebitis. Adult-onset asthma and periocular xanthogranuloma (AAPOX) is a rare disease of unknown aetiology characterized by violaceous or yellow cutaneous papules and nodules usually accompanied with adult-onset asthma. We report a case of IgG4RD associated with AAPOX. We also conducted a literature search with keywords including IgG4RD and AAPOX. A 36-year-old woman presented with bilateral exophthalmos and periorbital oedema. Keratoconjunctivitis sicca, painless left parotid gland and submandibular left lymph node enlargement were also noted. Two and half years ago biopsy of yellow plaques of her right lower eyelid confirmed periorbital xanthogranuloma. She underwent parotid gland biopsy which showed IgG4RD. She was treated with steroids and two cycles of rituximab with complete remission. The literature review revealed 8 articles describing 14 cases with IgG4RD and AAPOX, 9 men and 5 women (ratio M:F = 1.8:1) were affected. The age at diagnosis was greater in men compared to women. In the majority of patients, ophthalmic presentation included bilateral upper and lower eyelid swelling while systemic features were asthma, lacrimal and parotid involvement, lymphadenopathy, sclerosing pancreatitis and sclerosing cholangitis. Prednisone and rituximab were effective treatments. It has to be clarified whether the association between IgG4RD and AAPOX represents shared pathophysiology, a common underlying cause or coincidence. Rituximab added to steroids resulted in complete remission of the two entities.

Adult-Onset Asthma and Periocular Xanthogranulomas Associated with Systemic IgG4-Related Disease

PURPOSE

The aim of this study was to report a case of Adult-Onset Asthma with Periocular Xanthogranulomas (AAPOX) associated with systemic IgG4-related disease (IgG4-RD).

OBSERVATIONS

A 57-year-old man presented with bilateral periorbital swelling for 1 year. Histopathology of a left orbital biopsy showed fibro vascular connective tissue inundated with foamy, lipid-laden histiocytes and touton giant cells with lymphocytic inflammation. Additional stains revealed CD68 positivity, and S100 negativity. The IgG and IgG4 stained slides showed increased IgG4 positive plasma cells but did not meet the criteria for IgG4-related orbital disease. His IgG4 serology was elevated, and IgG4 staining of his tissue previously diagnosed as autoimmune sclerosing pancreatitis was found to meet the criteria for IgG4-RD.

CONCLUSIONS AND IMPORTANCE

AAPOX can be associated with systemic IgG4-RD.