Anti-pituitary antibodies as a marker of autoimmunity in pituitary glands.

Autoimmunity contributes to the pathogenesis of hypophysitis, a chronic inflammatory disease in the pituitary gland. Although primary hypophysitis is rare, the number of pituitary dysfunction cases induced by immune checkpoint inhibitors (ICIs) is increasing. While it is difficult to prove the involvement of autoimmunity in the pituitary glands, circulating anti-pituitary antibodies (APAs) can be measured by indirect immunofluorescence and used as a surrogate marker of pituitary autoimmunity. APAs are present in several pituitary diseases, including lymphocytic adenohypophysitis, lymphocytic infundibulo-neurohypophysitis (LINH), IgG4-related hypophysitis, and pituitary dysfunction induced by ICIs. Mass spectrometry analysis of antigens targeted by APAs clarified rabphilin-3A as an autoantigen in LINH. This demonstrates that APAs can be applied as a probe to identify novel autoantigens in other pituitary autoimmune diseases, including pituitary dysfunction induced by ICIs, which can aid in biomarker discovery.

A case series of atypical features of patients with biopsy-proven isolated IgG4-related hypophysitis and normal serum IgG4 levels.

BACKGROUND: IgG4-related hypophysitis is a rare clinical entity that forms part of an emerging group of multi-organ IgG4-related fibrosclerotic systemic diseases. The rare prevalence of the disease, presenting features that overlap with other sellar pathologies, and variable imaging features can make preoperative identification challenging. PURPOSE AND METHODS: We report three cases of isolated IgG4-related hypophysitis with atypical clinical and imaging features that mimicked those of pituitary apoplexy and other sellar lesions. Additionally, we review the literature of IgG4-related hypophysitis to provide context for individual patient data described herein. RESULTS: All patients presented with symptoms that mimicked those of pituitary apoplexy and visual disturbance, and MRI findings suggestive of pituitary macroadenoma, Rathke's cleft cyst and craniopharyngioma. The clinical presentation warranted surgical decompression, resulting in rapid symptomatic improvement. Preoperative high-dose followed by postoperative low-dose glucocorticoid replacement therapy was administered in all cases. Histopathology showed dense infiltrate of IgG4 cells. Post-operative follow-up monitoring for 12-26 months revealed normal serum IgG4 levels with no other organ involvement, while endocrinological testing revealed persistent pituitary hormone deficiencies. CONCLUSIONS: Our cases highlight the importance of considering IgG4-related hypophysitis in the differential diagnosis of solid and cystic sellar lesions presenting acutely with pituitary apoplexy symptoms. Existing diagnostic criteria may not be sufficiently precise to permit rapid and reliable identification, or avoidance of surgery in the acute setting. In contrast to other reports of the natural history of this condition, despite the severity of presenting features, the disease in our cases was pituitary-restricted with normal serum IgG4 levels.

Diabetes insipidus is an unfavorable prognostic factor for response to glucocorticoids in patients with autoimmune hypophysitis.

INTRODUCTION: Autoimmune hypophysitis (AH) has a variable clinical presentation and natural history; likewise, its response to glucocorticoid therapy is often unpredictable. OBJECTIVE: To identify clinical and radiological findings associated with response to glucocorticoids. DESIGN AND METHODS: 12 consecutive patients with AH, evaluated from 2008 to 2016. AH was the exclusion diagnosis after ruling out other pituitary masses and secondary causes of hypophysitis. Mean follow-up time was 30 ± 27 months (range 12-96 months). RESULTS: MRI identified two main patterns of presentation: global enlargement of the pituitary gland or panhypophysitis (n = 4, PH), and pituitary stalk abnormality only, or infundibulo-neuro-hypophysitis (n = 8, INH). Multiple tropin defects were more common in PH (100%) than those in INH (28% P = 0.014), whereas diabetes insipidus was more common in INH (100%) than that in PH (50%; P = 0.028). All 4 PH and 4 out of 8 INH were treated with glucocorticoids. Pituitary volume significantly reduced in all PH patients (P = 0.012), defective anterior pituitary function recovered only in the two patients without diabetes insipidus (50%) and panhypopituitarism persisted, along with diabetes insipidus, in the remaining 2 (50%). In all INH patients, either treated or untreated, pituitary stalk diameter reduced (P = 0.008) but diabetes insipidus persisted in all. CONCLUSIONS: Glucocorticoid therapy may improve anterior pituitary function in a subset of patients but has no effect on restoring posterior pituitary function. Diabetes insipidus appears as a negative prognostic factor for response to glucocorticoids.

Critical review of IgG4-related hypophysitis.

PURPOSE: IgG4-related hypophysitis is a rare disease, with only 34 cases published in English (2015). Available short reviews may not present complete details of IgG4-related hypophysitis. We aimed to survey case reports of IgG4-related hypophysitis, including abstracts of scientific meetings, in English and Japanese. METHODS: We searched for information about IgG4-related hypophysitis in PubMed and Igakuchuozasshi (Japan Medical Abstracts Society). Among 104 case reports found, we reviewed 84 fulfilling Leporati's diagnostic criteria. RESULTS: The mean ±  SD age of onset was 64.2  ±  13.9, 67.5  ±  9.8, and 56.4  ±  18.6 years for all subjects, men, and women, respectively. Men:women was 2.4:1. On magnetic resonance imaging, pituitary, stalk, and pituitary-stalk mass were observed at frequencies of 14.3, 21.4, and 64.3%, respectively. Manifestations were anterior hypopituitarism in 26.2% (22 cases), central diabetes insipidus in 17.9% (15 cases), and panhypopituitarism in 52.4% (44 cases). The median level of serum IgG4 was 264.5 mg/dL for all subjects, 405 mg/dL for men, and 226 mg/dL for women. The mean number of IgG4-related systemic diseases was 2.7  ±  1.5 in all subjects, 3.0  ±  1.5 in men, and 1.8  ±  1.1 in women. Among the IgG4-related diseases, retroperitoneal fibrosis was the most frequent (26.2%), followed by salivary gland diseases (25%). Glucocorticoid therapy was generally effective, except for two cases that received replacement doses. There were significant differences between sexes in terms of age, serum IgG4 levels, and number of IgG4-related diseases. CONCLUSION: IgG4-related hypophysitis may have different clinical characteristics between genders. This survey may lack some information because the Japanese abstracts did not contain certain details.

Longitudinal behavior of autoimmune GH deficiency: from childhood to transition age.

BACKGROUND: Some cases of apparently idiopathic GH deficiency (GHD) may be caused by pituitary autoimmunity. OBJECTIVE: To study the variations in pituitary function and antipituitary antibodies (APA) from childhood to transition age in patients with apparently idiopathic GHD. DESIGN: We conducted a longitudinal study. PATIENTS AND METHODS: Pituitary function and APA detection by immunofluorescence were investigated in 24 childhood patients with isolated GHD before starting recombinant GH therapy and after the stopping of this therapy in transition age. Sera of patients positive for APA were processed by double immunofluorescence to identify their pituitary target. RESULTS: At diagnosis, 16 out of 24 patients were APA positive targeting only somatotrophs (group 1), while the remaining eight were APA negative (group 2). When retested off therapy, 12 out of 16 patients in group 1 persisted being APA positive, while the remaining four became negative with recovery of pituitary function. All patients in group 2 persisted being APA negative but still showing GHD. Of the 12 patients persistently APA positive, eight with confirmed GHD showed APA still targeting somatotrophs, whereas four showed APA targeting only gonadotrophs associated with isolated hypogonadotropic hypogonadism (HH). CONCLUSION: Patients with APA at middle but not at high titer in childhood may show a remission of autoimmune GHD in childhood after GH replacement therapy. As APA may shift their target in transition period, an early characterization of APA by double immunofluorescence is advisable in APA positive GHD patients showing delayed puberty, to allow an early diagnosis and an appropriate therapy, thus preventing the progression toward HH.

HLA Markers DQ8 and DR53 Are Associated With Lymphocytic Hypophysitis and May Aid in Differential Diagnosis.

IMPORTANCE: Lymphocytic hypophysitis (LH) is a poorly understood autoimmune disorder of the pituitary gland. Symptoms include headache, pituitary dysfunction, visual disturbances, and neurological deficits. The diagnosis can be made based on clinical and biochemical findings, but for atypical presentations, no circulatory diagnostic biomarkers exist, and a pituitary biopsy is necessary for diagnosis. OBJECTIVES: We used high-resolution human leukocyte antigen (HLA) screening assays to investigate a relationship between specific HLA markers and LH. DESIGN: This was a retrospective analysis. SETTING: The study was conducted at a tertiary referral center. SUBJECTS: Fifteen patients with sporadic LH, 4 patients with melanoma who developed hypophysitis after administration of cytotoxic T lymphocyte antigen 4 (CTLA4) antibodies, and 1 patient with sarcoid-associated hypophysitis were evaluated. INTERVENTION: Clinical data, including endocrine function, were assessed, and HLA typing was performed in all 20 patients with hypophysitis, 50 control patients with other sellar abnormalities, and 4 CTLA4 antibody-treated patients without hypophysitis. RESULTS: Two major histocompatibility class II HLA markers, DQ8 and DR53, were found in 13 of 15 (87%) and 12 of 15 (80.0%) patients with sporadic LH, respectively. In contrast, none of the 4 patients who developed hypophysitis after administration of the CTLA4 antibodies exhibited the HLA-DQ8 marker and only 1 of 4 (25%) exhibited the HLA-DR53 marker. In a parallel group of 50 control subjects with sellar masses and 4 CTLA4 antibody-treated patients who did not develop evidence of pituitary failure, the candidate HLA subtypes were found in ∼20% for DQ8 and ∼48% for DR53, respectively. CONCLUSION AND RELEVANCE: The HLA markers, DQ8 and DR53, were found to be commonly present in patients with LH. The odds ratio of a patient with LH expressing the HLA-DQ8 marker is 23.1-fold higher than that of a patient with another sellar mass. HLA-DQ8 testing may assist in diagnosis and avoid unnecessary biopsies in patients with atypical LH.

Role of F-18 FDG PET/CT in assessing IgG4-related disease with inflammation of head and neck glands.

PURPOSE: The aim of the current study was to evaluate the utility of F-18-fluoro-2-deoxy-D-glucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) in assessing patients diagnosed with immunoglobulin G4 (IgG4)-related disease (IgG4-RD) with inflammation of the head and neck glands. METHODS: We reviewed the records of 17 patients (16 men and 1 woman) with IgG4-RD exhibiting inflammation of the head and neck glands (lacrimal or salivary glands; LSG) who were diagnosed by excisional biopsy of the LSG. F-18 FDG PET/CT images were retrospectively evaluated for locations of high FDG accumulation, and the maximum standardized uptake value (SUVmax) of each lesion was calculated. RESULTS: In 15 of 17 patients (88 %), FDG accumulation was observed in organs outside of the biopsied LSG. High FDG accumulation was most frequently seen in the lymph node (71 %), followed by the non-biopsied LSG (41 %). FDG accumulation was also found in other typically affected organs including the prostate and retroperitoneum (18 %), kidney and lung (12 %), and pancreas (1 %). FDG accumulation was most commonly observed in two lesions outside of the biopsied site (41 %). CONCLUSIONS: Detection of the multi-organ involvement before treatment is important for patients with IgG4-RD. F-18 FDG PET/CT is an effective tool for assessing the location of extra-LSG lesions in patients with IgG4-RD with LSG inflammation.

Autoimmune hypophysitis: new developments.

Autoimmune hypophysitis, often referred to as lymphocytic hypophysitis, is defined as an inflammatory condition of the pituitary gland of autoimmune etiology that leads to pituitary dysfunction. However, the pathogenesis of autoimmune hypophysitis is still incompletely defined. Although pathogenic autoantibodies in autoimmune hypophysitis have not yet been reported, it has been suggested that several antibodies may be closely related to pathogenesis. Novel clinical entities that are associated with hypophysitis, such as IgG4-related hypophysitis and anti-PIT-1 antibody syndrome, have recently been reported. The findings demonstrate the heterogeneity of the disease and provide important clues for understanding the pathogenesis and definition of hypophysitis, as well as the significance of antipituitary antibodies. This review focuses on new developments in autoimmune hypophysitis.