Lymphocytic hypophysitis: report of two biopsy-proven cases and one suspected case with pituitary autoantibodies

Successful treatment of medically and surgically refractory lymphocytic hypophysitis with fractionated stereotactic radiotherapy: a single-center experience and systematic literature review

PURPOSE

To explore the potential role of focused radiotherapy in managing the lymphocytic hypophysitis (LH) refractory to medical therapy and surgery.

METHOD

A systematic literature review was conducted following PRISMA guidelines to identify the studies on radiation treatment for hypophysitis, along with the experience in our institution.

RESULTS

The study included eight patients, three from our institution and five from existing literature. The age at presentation ranged from 37 to 75 years old, with a median age of 58. The presenting symptoms involved headache in seven patients and diplopia in two patients. Pre-radiation visual field defects were noticed in four patients. All patients exhibited variable degrees of hypopituitarism before radiation, with oral corticosteroids being the initial medical treatment. Immunosuppressive therapy was attempted in two patients prior to radiation. Seven patients had a history of transsphenoidal surgery with a histologically confirmed LH. Three patients underwent stereotactic radiosurgery (SRS), while the remaining received FSRT, with a mean irradiation volume of 2.2 cm3. A single-session total dose of 12 -15 Gy was administered in the SRS group. In the FSRT group, doses ranged from 24 to 30 Gy with a median dose of 25 Gy, delivered in 2 Gy fractions. Four patients achieved a resolution of visual field defects, while another two patients demonstrated improvement in their associated focal neurologic deficits. No change in pre-existing endocrine status was shown after radiation, except in one patient. Clinical response was achieved in seven patients after a single course of radiation, while one patient required the second course. Six patients remained stable on low-dose glucocorticoid during at least a 12-month follow-up period, and one discontinued it entirely without experiencing relapse. Three patients demonstrated a complete radiologic response, while the remaining showed a partial radiologic response.

CONCLUSIONS

Focused radiation, including FSRT, can play a role in symptomatic relief, effective mass shrinkage, and minimizing radiation exposure to critical surrounding structures in patients with refractory LH. However, further research efforts are necessary to better clarify its effects and optimal dose planning.

Paraneoplastic autoimmune hypophysitis: An emerging concept

Pituitary autoimmunity is one of the principal causes of hypopituitarism. Additionally, hypophysitis is one of the immune-related adverse events associated with immunotherapy. Recent case-oriented research has revealed a novel type of autoimmune hypophysitis, anti-PIT-1 hypophysitis, related to isolated adrenocorticotropic hormone (ACTH) deficiency and immune checkpoint inhibitor-related hypophysitis, as a form of paraneoplastic syndrome. Under these conditions, the ectopic expression of pituitary antigens present in tumors evokes a breakdown of immune tolerance, resulting in the production of autoantibodies and autoreactive cytotoxic T cells that specifically harm pituitary cells. Consequently, an innovative clinical entity of paraneoplastic autoimmune hypophysitis has been purported. This novel concept and its underlying mechanisms provide clues for understanding the pathogenesis of autoimmune pituitary diseases and can be applied to other autoimmune diseases. This review discusses the etiology of paraneoplastic autoimmune hypophysitis and its future.

Molecular and Genetic Immune Biomarkers of Primary and Immune-Therapy Induced Hypophysitis: From Laboratories to the Clinical Practice

Hypophysitis is a rare and potentially life-threatening disease, characterized by an elevated risk of complications, such as the occurrence of acute central hypoadrenalism, persistent hypopituitarism, or the extension of the inflammatory process to the neighboring neurological structures. In recent years, a large number of cases has been described. The diagnosis of hypophysitis is complex because it is based on clinical and radiological criteria. Due to this, the integration of molecular and genetic biomarkers can help physicians in the diagnosis of hypophysitis and play a role in predicting disease outcome. In this paper, we review current knowledge about molecular and genetic biomarkers of hypophysitis with the aim of suggesting a possible integration of these biomarkers in clinical practice.

Recent insights into the pathogenesis of autoimmune hypophysitis

INTRODUCTION

Hypophysitis is an inflammation of the pituitary gland and a rare case of hypopituitarism. Despite the expanding spectrum of histological variants and causative agents, its pathogenesis is far to be fully understood. The present review is focused on recent evidence concerning the pathogenesis of autoimmune hypophysitis by searching through online databases like MEDLINE and Scopus up to May 2021.

AREAS COVERED

Hypophysitis frequently develops in the context of a strong autoimmune background, including a wide spectrum of subtypes ranging from the commonest form of lymphocytic hypophysitis to the newly described and less common IgG4-, anti-PIT-1, and ICI-induced forms. A peculiar combination of genetic predisposition, pituitary damage and immunological setting represents the pathogenetic basis of autoimmune hypophysitis, which is characterized by diffuse infiltration of the gland by lymphocytes and variable degrees of fibrosis followed by pituitary cell destruction. Anti-pituitary antibodies (APA) have been described in sera from patients suffering from autoimmune hypophysitis, though their pathophysiological significance remains largely unknown and their diagnostic value limited.

EXPERT OPINION

In recent years hypophysitis has gained interest due to the increased number of new diagnoses and the recognition of novel subtypes. Further studies could lead to improvements in biochemical/immunological diagnosis and targeted treatments.

Anti-pituitary antibodies and susceptible human leukocyte antigen alleles as predictive biomarkers for pituitary dysfunction induced by immune checkpoint inhibitors

BACKGROUND

Pituitary dysfunction is a life-threatening immune-related adverse event (irAE) induced by immune checkpoint inhibitors (ICIs). To date, it is not possible to identify patients who may develop pituitary irAEs prior to ICI treatment. The aim of this study was to characterize the predisposition for ICI-induced pituitary irAEs by analyzing anti-pituitary antibodies (APAs) and human leukocyte antigens (HLAs).

METHODS

In this case-control study, APAs and HLA alleles were analyzed in 62 patients (17 who developed ICI-induced isolated adrenocorticotropic hormone deficiency (ICI-IAD), 5 who developed ICI-induced hypophysitis (ICI-H) and 40 who did not develop pituitary irAEs) treated with ICIs between November 2, 2015, and March 31, 2020, at Nagoya University Hospital. The main outcome measures in this study were the association between the development of pituitary irAEs with APAs at baseline and after treatment and HLA alleles.

RESULTS

Eleven of 17 (64.7%) patients who developed ICI-IAD had APAs at baseline, whereas APAs were positive only in 1 of 40 (2.5%) control patients. Although APAs were negative at baseline in all patients who developed ICI-H, they had become positive before the onset of ICI-H in 3 of 4 patients several weeks after ipilimumab administration. At the onset of ICI-IAD and ICI-H, APAs were positive in 15 of 17 (88.2%) and 4 of 5 (80%) patients, respectively. The prevalence of HLA-Cw12, HLA-DR15, HLA-DQ7, and HLA-DPw9 was significantly higher in patients with ICI-IAD, whereas that of HLA-Cw12 and HLA-DR15 was significantly higher in patients with ICI-H than in controls.

CONCLUSIONS

This study showed distinct and overlapped patterns of APAs and HLA alleles between ICI-IAD and ICI-H. Our findings also showed that positive APAs at baseline and after treatment, together with susceptible HLA alleles, could become predictive biomarkers for ICI-IAD and ICI-H, respectively.

TRIAL REGISTRATION NUMBER

UMIN000019024.

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.

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.

Hypophysitis in the era of immune checkpoint inhibitors and immunoglobulin G4-related disease

INTRODUCTION

Hypophysitis is a rare disorder, defined as inflammation of the pituitary gland that may result in pituitary enlargement and varying anterior and posterior pituitary hormonal deficits. It involves different histopathological subtypes and variable etiologies, with considerable overlap between classification systems. Histopathology is the gold standard diagnostic approach.

AREAS COVERED

In this article, we will review the major histopathological subtypes of hypophysitis with a special focus on immunoglobulin G4 (IgG4)-related hypophysitis and immune checkpoint inhibitor-induced hypophysitis, given their recent appearance and increasing incidence. We will summarize the similarities and differences between the different subtypes as it relates to epidemiology, pathogenesis, presentation, diagnosis, and management.

EXPERT OPINION

Hypophysitis is a heterogeneous and wide term used to describe different, possibly distinct diseases often with poorly understood pathogenesis. It involves a wide range of subtypes with certain differences in incidence rates, pathogenesis, and management. Management usually focuses on relieving the mass effect symptoms and replacing the deficient pituitary hormones. Spontaneous recovery is possible but recurrence is not uncommon.

New causes of hypophysitis

Hypophysitis is a rare entity characterized by inflammation of the pituitary gland and its stalk that can cause hypopituitarism and/or mass effect. Etiology can be categorized as primary or secondary to systemic disease, but may also be classified according to anatomical and hispathological criteria. Newly recognized causes of hypophysits have been described, mainly secondary to immunomodulatory medications and IgG4-related disease. Diagnosis is based on clinical, laboratory and imaging data, whereas pituitary biopsy, though rarely indicated, may provide a definitive histological diagnosis. For the clinician, obtaining a broad clinical and drug history, and performing a thorough physical examination is essential. Management of hypophysitis includes hormone replacement therapy if hypopituitarism is present and control of the consequences of the inflammatory pituitary mass (e.g. compression of the optic chiasm) using high-dose glucocorticoids, whereas pituitary surgery is reserved for those unresponsive to medical therapy and/or have progressive disease. However, there remains an unmet need for controlled studies to inform clinical practice.

MECHANISMS IN ENDOCRINOLOGY: Hypophysitis: diagnosis and treatment

Hypophysitis is a rare condition characterised by inflammation of the pituitary gland, usually resulting in hypopituitarism and pituitary enlargement. Pituitary inflammation can occur as a primary hypophysitis (most commonly lymphocytic, granulomatous or xanthomatous disease) or as secondary hypophysitis (as a result of systemic diseases, immunotherapy or alternative sella-based pathologies). Hypophysitis can be classified using anatomical, histopathological and aetiological criteria. Non-invasive diagnosis of hypophysitis remains elusive, and the use of currently available serum anti-pituitary antibodies are limited by low sensitivity and specificity. Newer serum markers such as anti-rabphilin 3A are yet to show consistent diagnostic value and are not yet commercially available. Traditionally considered a very rare condition, the recent recognition of IgG4-related disease and hypophysitis as a consequence of use of immune modulatory therapy has resulted in increased understanding of the pathophysiology of hypophysitis. Modern imaging techniques, histological classification and immune profiling are improving the accuracy of the diagnosis of the patient with hypophysitis. The objective of this review is to bring readers up-to-date with current understanding of conditions presenting as hypophysitis, focussing on recent advances and areas for future development. We describe the presenting features, investigation and diagnostic approach of the patient with likely hypophysitis, including existing conventional techniques and those in the research/development arena. Hypophysitis usually results in acute and persistent pituitary hormone deficiency requiring long-term replacement. Management of hypophysitis includes control of the inflammatory pituitary mass using a variety of treatment strategies including surgery and medical therapy. Glucocorticoids remain the mainstay of medical treatment but other immunosuppressive agents (e.g. azathioprine, rituximab) show benefit in some cases, but there is a need for controlled studies to inform practice.

Pituitary Microsomal Autoantibodies in Patients with Childhood-Onset Combined Pituitary Hormone Deficiency: an Antigen Identification Attempt

The role of autoimmunization in the pathogenesis of pituitary disorders is poorly understood. The presence of pituitary autoantibodies (APA) has been detected in various pituitary disorders. Their role, however, remains elusive. Childhood-onset combined pituitary hormone deficiency (CPHD) may be caused by environmental or genetic factors. In some of patients, causes of the disease remain unclear and contributions of autoimmune processes have been postulated. The aim of this study was to identify the microsomes-derived pituitary antigens (MPA) as potential immunogenic autoantigens in patients with hypopituitarism, therefore 62 CPHD patients, 100 healthy controls and five autoimmune polyglandular syndrome type II (APS II) patients were included in the study. The clinical evaluation included hormonal tests and magnetic resonance imaging of the pituitary. The sources of MPA were pituitary glands taken from autopsies. Isolated MPA were then separated on SDS-PAGE gel and incubated with sera obtained from patients and controls. Microsomal APA were detected using Western blot and radioimmunological method. In all CPHD and APS II patients and in 9 % individuals from control group marked immunoreactivity was detected against MPA. Antibodies showed high affinity to 67, 60, 50 and 36 kDa MPAs. Since the identified autoantigens were of unknown nature, an in silico exploration of UniProt database was applied and indicated their possible relationship with chaperones, golgins and already known autoantigens like GAD67. Reactivity against MPA indicates that these proteins certainly play a role in the processes undergoing within pituitary of CPHD patients. The identification and further detailed studies on their role in the pathogenesis of CPHD should be continued.

Hypophysitis: Evaluation and Management

Hypophysitis is the acute or chronic inflammation of the pituitary gland. The spectrum of hypophysitis has expanded in recent years with the addition of two histologic subtypes and recognition as a complication of treatment with immune checkpoint inhibitors. Despite the increased number of published cases, the pathogenesis of hypophysitis is poorly understood, and treatment strategies are diverse and controversial. The diagnosis of hypophysitis generally requires histopathologic confirmation. The presentation and clinical course of hypophysitis varies. Hypophysitis can resolve spontaneously, relapse may occur, and some cases can be refractory to treatment.

VARIATIONS IN CLINICAL AND IMAGING FINDINGS BY TIME OF DIAGNOSIS IN FEMALES WITH HYPOPITUITARISM ATTRIBUTED TO LYMPHOCYTIC HYPOPHYSITIS

OBJECTIVE

To describe the various patterns of presentation, including assisting analyses, associated with the timing of diagnosis of females with hypopituitarism and suspected clinical diagnosis of lymphocytic hypophysitis.

METHODS

A retrospective study of 9 consecutive females with pituitary dysfunction developed during or after pregnancy. All subjects were treated in our clinics between 2008 and 2014. Data were collected on clinical characteristics, pituitary hormone levels, and imaging findings.

RESULTS

The study group included 9 patients with a mean age 33.7 ± 7.8 years at delivery. The probable cause of disease was lymphocytic hypophysitis. Headache or specific symptoms/signs of hypopituitarism appeared within 1 year of delivery. Five patients had headache, and 8 had difficulty breastfeeding or amenorrhea. Laboratory findings included central hypocortisolism (8/9 patients), hypogonadotropic hypogonadism (8/9), and central hypothyroidism (6/7). Insulin-like growth factor-1 (IGF-1) levels were low in 8/8 patients. Prolactin levels were low in 3/9 patients, and 1 patient had diabetes insipidus. Seven patients were diagnosed less than 1 year from symptom onset; 4 (57%) complained of headaches, and 5 (71%) had panhypopituitarism. Two patients were diagnosed later. Both had difficulty breastfeeding and amenorrhea, and one also had headaches. Both had panhypopituitarism and reduced pituitary volume. None of the patients fully recovered pituitary function. Normalization of the thyrotroph axis occurred in 3 patients, gonadotroph function in 3, the corticotroph axis in 2, and IGF-1 normalized in 1 subject.

CONCLUSION

Hypopituitarism attributed to lymphocytic hypophysitis may present during pregnancy or early postpartum period with a clear clinical picture, or later, with indolent and nonspecific symptoms and signs.

Rabphilin-3A as a Targeted Autoantigen in Lymphocytic Infundibulo-neurohypophysitis

CONTEXT

Central diabetes insipidus (CDI) can be caused by several diseases, but in about half of the patients the etiological diagnosis remains unknown. Lymphocytic infundibulo-neurohypophysitis (LINH) is an increasingly recognized entity among cases of idiopathic CDI; however, the differential diagnosis from other pituitary diseases including tumors can be difficult because of similar clinical and radiological manifestations. The definite diagnosis of LINH requires invasive pituitary biopsy.

OBJECTIVE

The study was designed to identify the autoantigen(s) in LINH and thus develop a diagnostic test based on serum autoantibodies.

DESIGN

Rat posterior pituitary lysate was immunoprecipitated with IgGs purified from the sera of patients with LINH or control subjects. The immunoprecipitates were subjected to liquid chromatography-tandem mass spectrometry to screen for pituitary autoantigens of LINH. Subsequently, we made recombinant proteins of candidate autoantigens and analyzed autoantibodies in serum by Western blotting.

RESULTS

Rabphilin-3A proved to be the most diagnostically useful autoantigen. Anti-rabphilin-3A antibodies were detected in 22 of the 29 (76%) patients (including 4 of the 4 biopsy-proven samples) with LINH and 2 of 18 (11.1%) patients with biopsy-proven lymphocytic adeno-hypophysitis. In contrast, these antibodies were absent in patients with biopsy-proven sellar/suprasellar masses without lymphocytic hypophysitis (n = 34), including 18 patients with CDI. Rabphilin-3A was expressed in posterior pituitary and hypothalamic vasopressin neurons but not anterior pituitary.

CONCLUSIONS

These results suggest that rabphilin-3A is a major autoantigen in LINH. Autoantibodies to rabphilin-3A may serve as a biomarker for the diagnosis of LINH and be useful for the differential diagnosis in patients with CDI.

Central hypothyroidism in adults: better understanding for better care

Central hypothyroidism (CH) is a rare cause of hypothyroidism generally related to a hypothalamic-pituitary disorder or arising as an iatrogenic complication. In adults, CH may be secondary to quantitative and/or qualitative alterations in thyroid-stimulating hormone (TSH) secretion. The disease is difficult to diagnose clinically because it lacks specific clinical signs and these may be masked by other anterior pituitary hormone secretion deficiencies. In patients with long-standing and marked CH, a diagnosis may be made based on low free T4 levels and normal, low or moderately increased TSH levels. In patients with early-stage or moderate CH, exploration of the circadian TSH cycle, determination of TSH response after a TRH test or recombinant TSH injection, estimation of TSH index, or evaluation of peripheral indexes of thyroid hormone metabolism may be required to establish a diagnosis. Regarding treatment, patients should receive levothyroxine replacement therapy, but hormone objectives during follow-up need to be precisely determined in order to reduce cardiovascular risks and to improve the quality of life of patients.

Identification of the novel autoantigen candidate Rab GDP dissociation inhibitor alpha in isolated adrenocorticotropin deficiency

Isolated adrenocorticotropin deficiency (IAD) is characterized by low or absent adrenocorticotropic hormone (ACTH) production. IAD is presumed to be caused in part by an autoimmune mechanism, and several lines of evidence have suggested the presence of anti-pituitary antibodies in IAD. However, the exact autoantigens remain unknown. The present study was designed to identify the autoantigen(s) in IAD using chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Rat anterior pituitary lysate was subjected to SDS-PAGE, and immunoblotting was performed using the sera from two patients with IAD and from a healthy subject. The bands detected by the patient serum samples, but not by the healthy subject sample, were excised, in-gel digested using trypsin, and subjected to LC-MS/MS analysis. On immunoblots, a 51-kDa band in the insoluble pellet was detected by the sera from the IAD patients but not from the healthy subject. Mass spectrometric analysis revealed the 51-kDa band contained Rab guanine nucleotide dissociation inhibitor (GDI) alpha. Consistent with the mass spectrometric analysis, a recombinant full-length human Rab GDI alpha was recognized by the two IAD patient samples but not by the healthy subject sample using immunoblotting. In total, anti-Rab GDI alpha antibodies were detected in serum samples from three of five patients with IAD (60%) but were absent in 5 healthy subjects. In addition, Rab GDI alpha was expressed in the anterior pituitary. In conclusion, it appears that Rab GDI alpha is a candidate autoantigen involved in IAD, and that anti-Rab GDI alpha antibodies are present predominantly in patients with IAD.

The optic chiasm

The optic chiasm is formed when the optic nerves come together in order to allow for the crossing of fibers from the nasal retina to the optic tract on the other side. This enables vision from one side of both the eyes to be appreciated by the occipital cortex of the opposite side. This review makes note of the embryology, anatomy and vascular supply of the optic chiasm, then discusses the clinical syndromes associated with chiasmal disease, and the diseases which commonly influence its function.

Pituitary gonadotropins and autoimmunity

Autoimmune disease occurs when the body produces an inappropriate immune response against its own tissues producing antibodies, called autoantibodies, reacting to specific antigens. Studies regarding the presence of an autoimmune process specifically involving gonadotropins date from over than 20 years ago, when antibodies to gonadotropic-secreting cells were found by immunofluorescence in sera from a group of patients affected by cryptorchidism. Later on, antibodies detected by the same technique, and directed to the same cells were also found at high titer in sera from patients affected by hypogonadotropic hypogonadism, Kallmann's syndrome, lymphocytic hypophysitis with isolated gonadotropin deficiency, as well as autoimmune polyendocrine syndrome. Concerning the autoimmune target/s within the gonadotropic cells, rarely autoantibodies were found labeling gonadotropins while in a large number of cases, auto-antigens remained to be identified. Since pituitary gonadotropins are fundamental for the sexual maturity and reproductive mechanisms, patients with infertility were largely investigated by enzyme-linked immunosorbent assay for the presence of circulating antibodies likely interfering with gonadotropin activity. In infertile women, autoantibodies to gonadotropins were found related to ovarian autoimmunity, ovarian disorders that cause infertility and also associated with in vitro fertilization treatments. In infertile men, autoantibodies to gonadotropins may alter the testicular spermatogenesis and cause apoptosis of the spermatogenic cells. In conclusion, circulating antibodies were found labeling gonadotropic cells and/or gonadotropins, and in both cases they could create dysfunctions in gonadotropin related mechanism. The intriguing question of what can cause the production of such autoantibodies is not clear yet.

Intermediate lobe immunoreactivity in a patient with suspected lymphocytic hypophysitis

Lymphocytic hypophysitis is an organ-specific autoimmune disease characterised by destruction of pituitary hormone-secreting cells due to attack by self-reactive T lymphocytes. The spectrum of pituitary autoantibodies characterised by indirect immunofluorescence (IF) in these patients has not been substantially defined. The purpose of this study was to determine the spectrum of pituitary autoantibodies in 16 lymphocytic hypophysitis patients. Pituitary sections were prepared from guinea pigs and sera from 16 lymphocytic hypophysitis patients (13 biopsy proven and 3 suspected cases) and 13 healthy controls were evaluated for immunoreactivity to the pituitary tissue by immunofluorescence. A single patient was found to have high titre pituitary autoantibodies against guinea pig pituitary tissue. Immunoreactivity was directed against cells of the intermediate lobe. We present the case report of the patient who is a 24 year old woman that presented with headaches, polyuria and polydipsia. A uniformly enlarged pituitary mass was visible on MRI and a diagnosis of suspected lymphocytic hypophysitis was made. Based on our IF study, we postulate this patient has an autoimmune process directed towards the major cell type in the intermediate lobe, the melanotroph. Pre-adsorption with peptides representing adrenocorticotropic hormone, α-melanocyte stimulating hormone or β-endorphin did not affect the IF signal suggesting our patient's pituitary autoantibodies may target some other product of Proopiomelanocortin (POMC) processing, such as corticotrophin-like intermediate peptide or γ-lipoprotein. Alternatively, the autoantibodies may target a peptide completely unrelated to POMC processing.

Growth hormone and proopiomelanocortin are targeted by autoantibodies in a patient with biopsy-proven IgG4-related hypophysitis

Hypophysitis is a chronic inflammation of the pituitary gland often caused by autoimmunity. Among the autoimmune diseases it is one of the few where the autoantigens remain to be identified. The goal of the paper was to characterize the antigenic profile in a previously reported patient with IgG4-related hypophysitis. Immunofluorescence and immunoblotting were performed to detect antibodies to human pituitary proteins. The proteins recognized by western blotting were then submitted to mass spectrometry for sequencing. The patient's autoantibodies recognized two unique bands around 40 and 30 kDa on immunoblotting. Sequencing revealed one peptide from proopiomelanocortin in the 40 kDa band and four peptides from growth hormone in the 30 kDa band. This work represents the first antigenic profile in IgG4-related hypophysitis, and the first recognition of proopiomelanocortin as a possible pituitary autoantigen. In addition, the work supports previous suggestions of growth hormone as a pituitary autoantigen. Further studies are needed to prove the pathogenicity and diagnostic utility of these two pituitary proteins.

Identification of TPIT and other novel autoantigens in lymphocytic hypophysitis: immunoscreening of a pituitary cDNA library and development of immunoprecipitation assays

BACKGROUND

Lymphocytic hypophysitis is an organ-specific autoimmune disease of the pituitary gland. A specific and sensitive serological test currently does not exist to aid in the diagnosis.

OBJECTIVE

To identify target autoantigens in lymphocytic hypophysitis and develop a diagnostic assay for these proteins.

DESIGN/METHODS

A pituitary cDNA expression library was immunoscreened using sera from four patients with lymphocytic hypophysitis. Relevant cDNA clones from screening, along with previously identified autoantigens pituitary gland-specific factor 1a and 2 (PGSF1a and PGSF2) and neuron-specific enolase (NSE) were tested in an in vitro transcription and translation immunoprecipitation assay. The corticotroph-specific transcription factor, TPIT, was investigated separately as a candidate autoantigen.

RESULTS

Significantly positive autoantibody reactivity against TPIT was found in 9/86 hypophysitis patients vs 1/90 controls (P = 0.018). The reactivity against TPIT was not specific for lymphocytic hypophysitis with autoantibodies detectable in the sera from patients with other autoimmune endocrine diseases. Autoantibodies were also detected against chromodomain-helicase-DNA binding protein 8, presynaptic cytomatrix protein (piccolo), Ca(2+)-dependent secretion activator, PGSF2 and NSE in serum samples from patients with lymphocytic hypophysitis, but at a frequency that did not differ from healthy controls. Importantly, 8/86 patients with lymphocytic hypophysitis had autoantibodies against any two autoantigens in comparison with 0/90 controls (P = 0.0093).

CONCLUSIONS

TPIT, a corticotroph-specific transcription factor, was identified as a target autoantigen in 10.5% of patients with lymphocytic hypophysitis. Further autoantigens related to vesicle processing were also identified as potential autoantigens with different immunoreactivity patterns in patients and controls.

Pregnancy and other pituitary disorders (including GH deficiency)

The pituitary gland is one of the most affected organs with altered anatomy and physiology during pregnancy. Acromegaly is the second most common pituitary adenoma seen in relation to gestation after prolactinomas. Acromegaly should be treated before conception to prevent potential tumor growth in patients who desire fertility. Medical therapy can be ceased safely after confirmation of pregnancy in acromegalic patients, but octreotide may be used in selected cases with compressive signs. Other hormonal and non-functional tumors are rarer and have been presented as case reports. Sheehan's syndrome, which is one of the most common causes of hypopituitarism in developing countries, and lymphocytic hypophysitis are known to be associated with pregnancy. They usually result in hypopituitarism, sometimes with delays in diagnosis and difficulties in differential diagnosis. Pregnancy is not common among patients with hypopituitarism or pituitary adenomas due to altered gonadotroph functions. Ovulation induction is essential for fertility achievement, but the replacement of other deficient pituitary hormones, including GH, seems to play an important role in the preparation of the uterus for implantation of the embryo.

Diagnosis and treatment of autoimmune hypophysitis: a short review

Medical therapy of autoimmune hypophysitis with immunosuppressive drugs can be effective to induce remission of the disease by treating both pituitary dysfunction and compression symptoms. We describe the case of a 41-yr-old man with autoimmune hypophysitis in whom prednisone therapy induced remission of the disease but was followed by a sudden relapse after withdrawal. A second trial of corticosteroid was started and succeeded in inducing remission of the disease. Eight months after the second withdrawal pituitary function was restored, pituitary mass had disappeared, only partial diabetes insipidus remained unchanged. Review of the literature identified 30 articles, among case reports and case series, reporting a total of 44 cases of autoimmune hypophysitis treated with glucocorticoids and/or azathioprine. Combining all the cases, medical therapy resulted to be effective in reducing the pituitary mass in 84%, in improving anterior pituitary function in 45%, and in restoring posterior pituitary function in 41%. Clinical aspects of autoimmune hypophysitis are discussed and a possible algorithm for the diagnosis and treatment of the disease is proposed.

The optic chiasm

In the first part of this chapter the anatomy and vascular supply of the chiasm are recounted, and the visual symptoms that may arise in chiasmal disease are noted. The neuro-ophthalmic signs, including the pattern of visual field defects, appearance of the optic disc, and various uncommon clinical accompaniments, are described. The second part deals with a comprehensive list of disease processes that may directly or indirectly affect the chiasm. These are divided into inflammatory disorders, including sarcoidosis, multiple sclerosis, and idiopathic chiasmitis; infective disorders, including tuberculosis; and a large section on tumors, including pituitary adenomas, cysts, and choristomas, malignant disorders, including germ cell tumors and glioma, and meningioma; and finally vascular disorders and compression due to hydrocephalus. In each case the clinical features and management of the disorder are noted, as well as the prognosis for visual improvement following treatment.

Lymphocytic hypophysitis with diabetes insipidus in a young man

BACKGROUND

A 29-year-old man was referred to a multidisciplinary pituitary clinic with a 3.5-year history of central diabetes insipidus, initially presumed to be idiopathic based on a normal MRI scan of the pituitary gland. Subsequent scanning revealed a suprasellar mass, which demonstrated progressive enlargement on serial imaging. He also developed hypogonadotropic hypogonadism.

INVESTIGATIONS

Measurement of levels of serum morning fasting cortisol, adrenocorticotropic hormone, total testosterone, luteinizing hormone, follicle-stimulating hormone, prolactin, insulin-like growth factor 1, TSH and free T(4), MRI of the pituitary gland and a transsphenoidal biopsy of a pituitary mass were performed.

DIAGNOSIS

Lymphocytic hypophysitis presenting with diabetes insipidus, with development of hypogonadotropic hypogonadism and a suprasellar mass.

MANAGEMENT

The patient was treated with intranasal desmopressin and transdermal testosterone. The underlying lymphocytic hypophysitis was initially managed conservatively with serial MRI and visual field testing. No immunosuppressant medication was given and, aside from the diagnostic transsphenoidal biopsy, no surgical intervention was required. He subsequently developed secondary hypothyroidism, secondary adrenal insufficiency and growth hormone deficiency. These disorders were managed with levothyroxine and prednisone.

[Watch out for headaches at the end of a pregnancy! Do not miss an autoimmune hypositys]

We report the case of a 21-year-old pregnant women (36 WA) presenting intensive headaches and visual disturbances. Those sellar compression symptoms have made us suppose the diagnosis of autoimmune hypophysitis. MRI has confirmed the typical aspect of symmetric enlargement of the pituitary gland with a strong and homogenous enhancement after gadolinium. This pathology associated to a high morbidity and mortality due to partial or complete deficit of the anterior pituitary hormones, shall be reminded more often.

Gamma Knife surgery for lymphocytic hypophysitis

Lymphocytic hypophysitis is a relatively uncommon autoimmune inflammatory disorder affecting the pituitary gland. It most frequently occurs in women of child-bearing age. The authors report on their experience with a patient who presented with diplopia and marked enlargement of the pituitary gland. She underwent transsphenoidal surgery, and histopathological analysis confirmed the diagnosis of lymphocytic hypophysitis. The disease proved refractory to resection, and any attempt at withdrawal of corticosteroid therapy resulted in a return of the patient's symptoms and enlargement of the sellar contents.

The patient underwent Gamma Knife surgery (GKS) to the sella and both cavernous sinuses. After GKS, the patient was able to discontinue steroid therapy without return of her symptoms. Follow-up MR images demonstrated no evidence of recurrence of lymphocytic hypophysitis.

For persistent lymphocytic hypophysitis, GKS is a reasonable treatment option.

Empty sella may be the final outcome in lymphocytic hypophysitis

INTRODUCTION

Lymphocytic hypophysitis (LH) is an autoimmune disorder associated with the infiltration of the pituitary gland by lymphocytes leading to different degrees of hypopituitarism. Females are affected more frequently than males and the disease is usually associated with pregnancy or postpartum period.

CASE

We present a case of LH who was first diagnosed with diabetes insipidus and hyperprolactinemia. In the follow-up, the patient developed growth hormone, gonadotropin, and thyroid stimulating hormone deficiency. The typical appearance of increased stalk thickness and diffuse homogenous contrast enhancement of pituitary on magnetic resonance imaging resulted in empty sella by time.

CONCLUSION

The present case demonstrates the natural course of LH over a 13-year period in which the empty sella was the final outcome.

Novel autoantigens in autoimmune hypophysitis

BACKGROUND

Pituitary autoantibodies are found in autoimmune hypophysitis and other conditions. They are a marker of pituitary autoimmunity but currently have limited clinical value. The methods used for their detection lack adequate sensitivity and specificity, mainly because the pathogenic pituitary autoantigen(s) are not known and therefore antigen-based immunoassays have not been developed.

OBJECTIVES

This study aimed to identify novel pituitary autoantigens using sera as probes in proteomic assays. We also compared immunoblotting and immunofluorescence methods for their accuracy in diagnosing autoimmune hypophysitis.

STUDY DESIGN AND SUBJECTS

Twenty-eight sera from autoimmune hypophysitis cases (14 histologically proven and 14 clinically suspected) were compared to 98 sera from controls, which included 14 patients with pituitary adenomas, 48 with autoimmune thyroiditis (15 Graves' disease and 33 Hashimoto's thyroiditis) and 36 healthy subjects.

METHODS

All sera were tested against human pituitary cytosolic proteins separated by one-dimensional (1D) gel electrophoresis. The band recognition was analysed statistically to detect molecular weight regions preferentially recognized by hypophysitis sera. 2D gel immunoblotting and mass spectrometry were then used to sequence the protein spots of interest. Sera were also tested by immunofluorescence for their recognition of Macaca mulatta pituitary sections.

RESULTS

A single region in the 25-27-kDa range was recognized more often by hypophysitis cases than healthy subjects (P = 0.004) or patients with pituitary adenomas (P = 0.044). This region contained two novel candidate autoantigens: chromosome 14 open reading frame 166 (C14orf166) and chorionic somatomammotrophin. Immunoblotting positivity for the 25-27-kDa region yielded greater sensitivity (64%vs. 57%) and specificity (86%vs. 76%) than immunofluorescence in predicting histologically proven hypophysitis, although the performance was still inadequate to make immunoblotting a clinically useful test.

CONCLUSION

The study reports two novel proteins that could act as autoantigens in autoimmune hypophysitis. Further studies are needed to validate their pathogenic role and diagnostic utility.

Autoimmune hypophysitis of SJL mice: clinical insights from a new animal model

Autoimmune hypophysitis (AH) is a rare but increasingly recognized disease of the pituitary gland. Its autoantigens are unknown, and the management is difficult because it is often misdiagnosed as a nonsecreting adenoma. By immunizing female SJL/J mice with mouse pituitary extracts, we established a new mouse model of experimental AH. Immunized mice developed severe lymphocytic infiltration in the anterior pituitary that closely mimicked the human pathology. In the early phase of experimental AH, the pituitary enlarged, consistent with the compression symptoms reported by hypophysitis patients at presentation. In the florid phase, adrenal insufficiency and pituitary antibodies developed, in strong correlation with the pituitary pathology. In the late phase, hypothyroidism ensued, and the pituitary gland became atrophic. Using immune sera as probes in a two-dimensional immunoblotting screen followed by mass spectrometry, we identified several proteins that could function as pituitary autoantigens. These findings provide new insights into the pathogenesis of AH, and establish a platform for developing novel diagnostic biomarkers and therapeutics.