Immunoglobulin G4 (IgG4)-Related Hypophysitis

IgG4-related hypophysitis

Hypophysitis is a rare pituitary inflammatory disorder classified in different ways. Immunoglobulin G4-related disease (IgG4-RD), also a rare disease is a systemic fibro-inflammatory condition characterized by infiltration of tissue with IgG4-positive plasma cells; however prevalence of both of them probably is underestimated. In this paper, we present an Iranian patient with biopsy-proven IgG4-related hypophysitis and then review the clinical characteristics, laboratory, imaging, pathologic findings and therapeutic management as well as prognosis of 115 published cases of hypophysitis secondary to IgG4-related disease.

IgG4 hypophysitis: Diagnosis and management

IgG4-related hypophysitis is a rare disease, due to a lymphoplasmocytic IgG4 positive infiltration of the pituitary. Literature data are scarce, even though the description of cases has drastically increased over the last years. The aim of this review is to better characterize the natural history, the diagnosis and the management of IgG4-related hypophysitis, based on a clinical case, an exhaustive Pubmed research, and a reappraisal of the criteria for diagnosis. We will specifically focus on the differences with other etiologies of hypophysitis, in the aim of improving the diagnostic procedures for all the physicians who could have to take care of such patients.

Disease heterogeneity in IgG4-related hypophysitis: report of two histopathologically proven cases and review of the literature

IgG4-related hypophysitis (IgG4-RH) is a rare disease, which can occur singularly or as manifestation of a systemic IgG4-related disease (IgG4-RD). Less than one hundred cases have been reported in the literature, very few of which were histopathologically documented. We analyzed the clinical, radiological, and histopathological features of two cases of IgG4-RH, the former observed in a 66-year-old man in the context of an IgG4-RD, and the latter affecting a 21-year-old woman, as an isolated lesion. In addition, we performed a comprehensive review of the previously published histopathologically documented cases of IgG4-RH. Pituitary samples from both patients showed dense lymphoplasmacytic infiltration, interstitial and storiform fibrosis, and high numbers of IgG4-positive plasma cells, consistent with IgG4-RH. From the literature review, we retrieved 18 papers reporting a total of 22 cases of histopathologically documented IgG4-RH. The revision of these cases, also including the two reported herein, showed an equal distribution of IgG4-RH in the two sexes, albeit significant clinico-pathological variation was found between cases arisen in female and male patients, respectively. In detail, IgG4-RH females were affected in their second-third decade of life, with a solitary pituitary lesion, low IgG4 serum level, and frequent association with autoimmune disorders. By contrast, IgG4-RH in men was a disease of the elderly, often in the context of a systemic IgG4-RD, with high IgG4 serum levels. Our study shows that IgG4-RH, as currently defined, is a clinically heterogenous disease, with different features in the two sexes. Indeed, cases diagnosed in young women, as our case 2, mostly do not present other evidence of IgG4-RD and might be better classified as lymphocytic hypophysitis with abundant IgG4+ plasma cells. For this reason, the histopathological examination of the pituitary lesion, particularly in female patients, may still be useful for a correct differential diagnosis with other variants of primary hypophysitis.

Clinical Characteristics of 76 Patients with IgG4-Related Hypophysitis: A Systematic Literature Review

BACKGROUND

IgG4-related hypophysitis (IgG4-RH) is a rare disease, and its prevalence remains unclear. In recent years, an increasing number of cases have been reported because of the increasing recognition of this disease. We aimed to summarize case reports of IgG4-RH and outline the clinical features and outcomes.

METHODS

We performed PubMed search of articles using the search terms "hypophysitis [AND] IgG4." Consequently, only 54 English articles (76 cases) met Leporati's diagnostic criteria.

RESULTS

Of the 76 cases, the ratio of men to women was 1.5 : 1, and the age at diagnosis was 54.1 ± 17.8 years. The median IgG4 concentration was 405.0 mg/dl. Anterior hypopituitarism, isolated central diabetes insipidus, and panhypopituitarism were observed in 14 (18.4%), 12 (15.8%), and 44 (57.9%) cases, respectively. The sequence of anterior hormone deficiency was as follows: gonadotropin (68.4%), ACTH (63.2%), TSH (59.2%), GH (48.7%), and prolactin (42.1%). The median number of involved organs was 1.5, and the lung (18.4%), retroperitoneum (17.1%), kidney (15.8%), submandibular glands (14.5%), and pancreas (13.2%) were the common involved organs. Elevated IgG4 concentration and normal IgG4 level were in 42 (76.4%) and 13 (23.6%) cases, respectively. Patients with elevated serum IgG4 concentration were older (60.9 ± 14.3 vs 45.6 ± 17.4, p=0.001) and male-prone (78.6% vs 40.4%, p=0.003) and had a susceptibility of multiple organ involvement (78.6% vs 35.0%, p=0.001) compared to those with normal serum IgG4 levels. Males were older at disease onset (61.5 ± 12.6 vs 42.9 ± 18.8, p < 0.001) and had a higher IgG4 concentration (425.0 vs 152.5, p=0.029) and a greater number of involved organs (2.0 vs 0.0, p=0.001), while isolated hypophysitis was more prominent in female (63.3% vs 26.1%, p=0.001).

CONCLUSION

In this review, we found that there were different characteristics between different genders. Patients with elevated serum IgG4 level in terms of some clinical features were also different from those with normal serum IgG4 level. However, the data in this review were limited by bias and confounding. Further clinical studies with larger sample sizes are warranted.

Immunohistochemical Biomarkers in Diagnosis of Hematolymphoid Neoplasms of Endocrine Organs

The hematolymphoid infiltrations are challenging lesions in endocrine organs and tissues. The fourth edition of WHO classification of tumors of endocrine organs and the fourth edition of WHO classification of tumors of hematopoietic and lymphoid tissues are recently published. The updates in both fields include some new disease descriptions and prognostic markers. Our aim in this review article is to give practical diagnostic information about the most frequently seen hematolymphoid involvements of the pituitary gland, thyroid, and adrenal tissue. We designed the text in the order of organs and the contents according to the disease frequency. The pituitary gland and cellar region are the most frequently involved with Langerhans cell histiocytosis. Although it is very rare, Erdheim-Chester disease has recently been included in the classification and still needs more clear diagnostic definitions. Lymphoproliferative thyroid lesions and presentations create diagnostic problems for the pathologists. IGG4-related disease and its relation with thyroiditis is a new concept. There are many unknowns on pathobiology of the disease spectrum and discussion on defined diagnostic criteria of the IGG4-related thyroid diseases. The overlapping features of thyroiditis and primary thyroid lymphomas also create diagnostic difficulties. The frequently recognized primary hematolymphoid lesions of the endocrine organs may not be difficult to diagnose since they are expected lesions. The secondary involvement of hematolymphoid neoplasia may be more difficult to diagnose for an endocrine pathologist. In this review article, we aim to give brief description of the diseases and practical diagnostic approach by using optimum markers guided by the latest WHO classifications.

Hypophyseal Involvement in Immunoglobulin G4-Related Disease: A Retrospective Study from a Single Tertiary Center

This study aims to outline the clinical features and outcomes of IgG4-related hypophysitis (IgG4-RH) patients in a tertiary medical center. We reviewed clinical manifestations and imaging and pituitary function tests at baseline, as well as during follow-up. Ten patients were included. The mean age at diagnosis of IgG4-RH was 48.4 (16.0-64.0) years. An average of 3 (0-9) extrapituitary organs were involved. Five patients had panhypopituitarism, three had only posterior hypopituitarism, one had only anterior hypopituitarism, and one had a normal pituitary function. One patient in our study had pituitary mass biopsy, lacking IgG4-positive cells despite lymphocyte infiltration forming an inflammatory pseudotumor. Five patients with a clinical course of IgG4-RH less than nine months and a whole course of IgG4-RD less than two years were managed with glucocorticoids, while three patients with a longer history were administered glucocorticoids plus immunosuppressive agents. One patient went through surgical excision, and one patient was lost to follow-up. All patients showed a prompt response clinically, but only three patients had normalized serum IgG4 levels. Two patients who took medications for less than six months relapsed. Conclusions. IgG4-RD is a broad disease, and all physicians involved have to be aware of the possibility of pituitary dysfunction. Younger patients should be expected. The histopathological feature of pituitary gland biopsy could be atypical. For patients with a longer history, the combination of GC and immunosuppressive agents is favorable. Early and adequate courses of treatment are crucial for the management of IgG4-RH. With GC and/or immunosuppressant treatment, however, pituitary function or diabetes insipidus did not improve considerably.