[A case of suspected IgG4-related hypophysitis presented with panhypopituitarism and central diabetes insipidus].

A 78-year-old man complained of subacute general fatigue and anorexia, following diplopia and gait disturbance. He demonstrated wide-based and small-stepped gait without objectively abnormal ocular movements. Brain |MRI showed enlargement of the pituitary stalk and gland with uniform contrast enhancement. PET-CT showed FDG |uptake in the pituitary gland, mediastinal lymph nodes, and left hilar lymph nodes. Blood investigations revealed panhypopituitarism and high serum IgG4 levels up to 265 |mg/dl. Histopathological examination revealed no IgG4-positive cell infiltration in the biopsied mediastinal lymph nodes. However, we suspected IgG4-associated hypophysitis based on the clinical symptoms and MRI findings, which were markedly resolved with steroid. Central masked diabetes insipidus was manifested, but was improved with oral desmopressin. We should pay close attention to the fact that IgG4-related hypophysitis may present with various symptoms regarded as indefinite complaints related to aging or underlying diseases, especially in elderly patients with multimorbidity.

Imaging for assessment of cancer treatment response to immune checkpoint inhibitors can be complementary in identifying hypophysitis.

Introduction: Hypophysitis is reported in 8.5%-14% of patients receiving combination immune checkpoint inhibition (cICI) but can be a diagnostic challenge. This study aimed to assess the role of routine diagnostic imaging performed during therapeutic monitoring of combination anti-CTLA-4/anti-PD-1 treatment in the identification of hypophysitis and the relationship of imaging findings to clinical diagnostic criteria. Methods: This retrospective cohort study identified patients treated with cICI between January 2016 and January 2019 at a quaternary melanoma service. Medical records were reviewed to identify patients with a documented diagnosis of hypophysitis based on clinical criteria. Available structural brain imaging with magnetic resonance imaging (MRI) or computed tomography (CT) of the brain and 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography with computed tomography (FDG-PET/CT) were assessed retrospectively. The main radiological outcome measures were a relative change in pituitary size or FDG uptake temporally attributed to cICI. Results: There were 162 patients (median age 60 years, 30% female) included. A total of 100 and 134 had serial CT/MRI of the brain and FDG-PET/CT, respectively. There were 31 patients who had a documented diagnosis of hypophysitis and an additional 20 who had isolated pituitary imaging findings. The pituitary gland enlargement was mild, and the largest absolute gland size was 13 mm, with a relative increase of 7 mm from baseline. There were no cases of optic chiasm compression. Pituitary enlargement and increased FDG uptake were universally transient. High-dose glucocorticoid treatment for concurrent irAEs prevented assessment of the pituitary-adrenal axis in 90% of patients with isolated imaging findings. Conclusion: Careful review of changes in pituitary characteristics on imaging performed for assessment of therapeutic response to iICI may lead to increased identification and more prompt management of cICI-induced hypophysitis.

A novel approach to hypophysitis: outcomes using non-glucocorticoid immunosuppressive therapy.

OBJECTIVE: To determine pituitary function before and after nonglucocorticoid immunosuppressive therapy (NGIT) in subjects with hypophysitis and evaluate their clinical and radiologic outcomes. DESIGN: Retrospective, longitudinal study. METHODS: We reviewed a large database, selected subjects with hypophysitis treated with NGIT, and collected information on the duration of therapy, and clinical, hormonal, and radiologic outcomes. RESULTS: Twelve subjects met the inclusion criteria. Five subjects had primary hypophysitis (PH), while seven had secondary hypophysitis (SH) due to an underlying systemic inflammatory disease. Mean age ± SD was 48.0 ± 15.7 years and 40.9 ± 13.0 years, for PH and SH, respectively. The majority were female (PH 60% and SH 86%). BMI ± SD at presentation was 25.2 ± 2.5 kg/m2 and 26.8 ± 6.7 kg/m2 for PH and SH, respectively. The most common symptom at presentation was fatigue (75%). All PH subjects (100%) and 2 (28.6%) SH subjects had polyuria/polydipsia. There was a significant decrease in mean pituitary stalk thickness after NGIT (P = .0051) (mean duration 16.5 ± 4.8 months). New hormone loss or recovery occurred rarely. Mycophenolate mofetil was the most used NGIT: adverse effects prompted discontinuation in 2 out of 7 subjects. CONCLUSIONS: Subjects with hypophysitis receiving NGIT had stable or improved brain/pituitary magnetic resonance imaging findings with a significant decrease in pituitary stalk thickness. NGITs did not improve anterior pituitary function. Our findings suggest that NGIT may be considered as an alternative therapy for patients with hypophysitis who require immunosuppression.

Concurrent IgG4-related hypophysitis and clinically nonfunctioning gonadotroph pituitary neuroendocrine tumor.

BACKGROUND: Some patients develop immunoglobulin G4 (IgG4)-related hypophysitis associated with systemic diseases. More than 30 cases of IgG4-related hypophysitis have been reported. However, biopsy has rarely been performed in these patients, and none have had an associated pituitary neuroendocrine tumor (PitNET). We present a case of concurrent IgG4-related hypophysitis and PitNET. CASE PRESENTATION: A 56-year-old Japanese man arrived at the hospital with visual impairment, bitemporal hemianopia, and right abducens nerve palsy. Magnetic resonance imaging revealed pituitary body and stalk swelling as well as a small poorly enhanced right anterior lobe mass. Laboratory and loading test results suggested hypopituitarism. Because IgG4 level was elevated, a systemic examination was performed; multiple nodules were found in both lung fields. The diagnosis was based on an endoscopic transnasal biopsy of the pituitary gland. A histopathological examination revealed a marked infiltration of plasma cells into the pituitary gland, which was strongly positive for IgG4. The histological features of the resected tumor were consistent with those of gonadotroph PitNET, which was immunohistochemically positive for follicle-stimulating hormone-ß and steroidogenic factor-1, and no plasma cell infiltration was observed. Based on the histopathological examination results, steroid therapy was initiated, which reduced pituitary gland size and serum IgG4 levels. DISCUSSION AND CONCLUSIONS: This is the first reported case of IgG4-related hypophysitis with PitNET. Although no pathological findings indicating a relationship between the two conditions were found, we were able to preoperatively differentiate multiple lesions via detailed diagnostic imaging.

Neuroimaging of hypophysitis: etiologies and imaging mimics.

Hypophysitis is an inflammatory disease affecting the pituitary gland. Hypophysitis can be classified into multiple types depending on the mechanisms (primary or secondary), histology (lymphocytic, granulomatous, xanthomatous, plasmacytic/IgG4 related, necrotizing, or mixed), and anatomy (adenohypophysitis, infundibulo-neurohypophysitis, or panhypophysitis). An appropriate diagnosis is vital for managing these potentially life-threatening conditions. However, physiological morphological alterations, remnants, and neoplastic and non-neoplastic lesions may masquerade as hypophysitis, both clinically and radiologically. Neuroimaging, as well as imaging findings of other sites of the body, plays a pivotal role in diagnosis. In this article, we will review the types of hypophysitis and summarize clinical and imaging features of both hypophysitis and its mimickers.

Diffuse Basisphenoid Enhancement: Possible Differentiating Feature for Granulomatous Hypophysitis.

BACKGROUND AND PURPOSE: Granulomatous hypophysitis is a rare inflammatory condition of the pituitary gland with an imaging appearance that can overlap with that of pituitary adenoma. Differentiating the two before surgical resection can have important treatment implications. The purpose of our study was to determine whether it was possible to differentiate between granulomatous hypophysitis and pituitary adenoma on the basis of diffuse enhancing infrasellar basisphenoid bone marrow. MATERIALS AND METHODS: We present 3 cases, initially thought to be pituitary adenomas, that were pathology-proved granulomatous hypophysitis. The preoperative MR images were reviewed for diffuse, enhancing infrasellar basisphenoid bone marrow. For comparison, we reviewed 100 cases of pathology-proved pituitary adenoma for the same finding. Additionally, imaging findings including the sphenoid sinus pneumatization pattern, clinical history, laboratory values, and pathology results were reviewed. RESULTS: All 3 cases of granulomatous hypophysitis had diffuse enhancing infrasellar basisphenoid bone marrow. Conversely, this was not seen in any of the 100 pituitary adenomas. The patients with granulomatous hypophysitis were all women. Two patients had idiopathic granulomatous hypophysitis, and 1 had secondary granulomatous hypophysitis with sarcoidosis. Of the 100 patients with pituitary adenomas, 67 were women. The basisphenoid pneumatization patterns was as follows: 15 (type 2), 40 (type 3), and 45 (type 4). CONCLUSIONS: We present 3 cases of granulomatous hypophysitis with diffuse enhancement of the infrasellar basisphenoid bone marrow that was not seen in our 100 cases of pituitary adenomas. This imaging feature may be valuable for suggesting a diagnosis of granulomatous hypophysitis and avoiding surgical resection of what might otherwise be misdiagnosed as a pituitary adenoma.

Preoperative differentiation of hypophysitis and pituitary adenomas using a novel clinicoradiologic scoring system.

PURPOSE: Hypophysitis can clinically and radiologically mimic other nonfunctioning masses of the sella turcica, complicating preoperative diagnosis. While sellar masses may be treated surgically, hypophysitis is often treated medically, so differentiating between them facilitates optimal management. The objective of our study was to develop a scoring system for the preoperative diagnosis of hypophysitis. METHODS: A thorough literature review identified published hypophysitis cases, which were compared to a retrospective group of non-functioning pituitary adenomas (NFA) from our institution. A preoperative hypophysitis scoring system was developed and internally validated. RESULTS: Fifty-six pathologically confirmed hypophysitis cases were identified in the literature. After excluding individual cases with missing values, 18 hypophysitis cases were compared to an age- and sex-matched control group of 56 NFAs. Diabetes insipidus (DI) (p < 0.001), infundibular thickening (p < 0.001), absence of cavernous sinus invasion (CSI) (p < 0.001), relation to pregnancy (p = 0.002), and absence of visual symptoms (p = 0.007) were significantly associated with hypophysitis. Stepwise logistic regression identified DI and infundibular thickening as positive predictors of hypophysitis. CSI and visual symptoms were negative predictors. A 6-point hypophysitis-risk scoring system was derived: + 2 for DI, + 2 for absence of CSI, + 1 for infundibular thickening, + 1 for absence of visual symptoms. Scores ≥ 3 supported a diagnosis of hypophysitis (AUC 0.96, sensitivity 100%, specificity 75%). The scoring system identified 100% of hypophysitis cases at our institution with an estimated 24.7% false-positive rate. CONCLUSIONS: The proposed scoring system may aid preoperative diagnosis of hypophysitis, preventing unnecessary surgery in these patients.

[Clinical and radiological diagnosis of hypophysitis: a review of literature and own data].

This article presents a literature review of the various forms of hypophysitis, its varieties, as well as the problem of radiation diagnosis and treatment of this pathology. Hypophysitis is a poorly understood and multifactorial disease which the difficulty of diagnosing is not only to a variety of nonspecific clinical manifestations and hormonal research data, but also the ambiguous results of MRI studies, the lack of clear MR patterns. The article reflects the main histological types of hypophysitis, the peculiarities of diagnosis in connection with general clinical symptoms, outlines the features of each type of hypophysitis with their own clinical observations. This review is devoted to modern ideas about the clinical course of hypophysitis, presented a set of characteristic diagnostic signs of the disease according to MRI and the treatment algorithms recommended today are also highlighted. The article summarizes data from foreign literature and our own clinical observations in order to develop an optimal protocol for MRI studies in patients with suspected hypophysitis, to develop recommendations for radiologists and endocrinologists for the correct results interpretation. The uniqueness of this review is the lack of data on the clinic, diagnosis and treatment of hypophysitis in the Russian literature today.

Xanthomatous Hypophysitis: A Case Report and Comprehensive Literature Review.

Purpose: Xanthomatous hypophysitis (XHP) is an extremely rare form of primary hypophysitis for which there is a lack of clinical experience. A comprehensive understanding of its clinical characteristics, diagnosis and treatment is needed. Methods: Here, we report a case study and conduct a systematic review of XHP. Thirty-six cases were included, and their clinical manifestations, endocrine assessment, imaging features, treatment and follow-up data were collected and analyzed. Results: The mean age at diagnosis was 39.1 years, and females were predominant (75.0%). The most common symptom was headache (68.6%), and 66.7% of female patients presented menstrual disorders. The most common pituitary dysfunction was growth hormone (GH) deficiency. More than half of patients exhibited central diabetes insipidus (CDI). The majority of patients had an imaging presentation of a cystic lesion with peripheral enhancement. Pituitary stalk thickening was observed in half of the patients. Total lesion resection was achieved in 57.1% of cases. The recurrence rate after partial resection and biopsy was significantly higher than that after total lesion resection (57.1% vs. 0.0%, P = 0.0147). The most common pituitary hormone abnormalities to resolve after surgery were hyperprolactinemia (100.0%) and GH deficiency (91.7%). The typical pathological feature was inflammatory infiltration of foamy histiocytes, which showed positivity for CD68. Conclusion: Diagnosis of XHP is difficult when relying on clinical symptoms and imaging features. Therefore, surgical histopathology is necessary. Based on the available evidence, total lesion resection is recommended for treatment. However, the long-term prognosis for this rare disease remains unclear.

Hypophysitis: A comprehensive overview.

Hypophysitis is defined as inflammation of the pituitary gland. It is a heterogeneous condition as it can originate from different parts of the pituitary gland, can be caused by different pathophysiological processes, and can be isolated or the manifestation of a underlying systemic disease. Hypophysitis usually presents with endocrine deficiencies, including diabetes insipidus, with varying patterns. A subset of patients presents with mass effects. The last decades major progress has been made in the understanding of this disease. New forms are now recognized, new diagnostics are being developed, and specific treatments are proposed. This review provides an overview of the current knowledge on hypophysitis using an aetiology-based approach and provides the clinician with a stepwise approach to the patient with (suspected) hypophysitis.

Nivolumab induced hypophysitis in a patient with recurrent non-small cell lung cancer.

Nivolumab is a programmed death receptor-1 blocking monoclonal antibody which has been approved by United States Food and Drug Administration for patients with metastatic non-squamous non-small cell lung cancer. Endocrinopathies like thyroid dysfunction and adrenal insufficiency are its known immune related adverse effects. Hypophysitis is very rare and usually presents with minimal symptoms. We report development of hypophysitis in an 84-year-old female patient who developed a range of symptoms (fatigue, headache, nausea) as well as laboratory confirmation of both central hypothyroidism and central adrenal deficiency which is unusual in cases of nivolumab induced hypophysitis. The patient had well differentiated adenocarcinoma of the left upper lobe of the lung. She underwent wedge resection followed by chemotherapy and was started on nivolumab due to recurrence. After 14 cycles of nivolumab, she started complaining of intense fatigue. She was found to have central thyroid deficiency and was started on levothyroxine. But her symptoms did not improve. Then she underwent adrenocorticotropic hormone stimulation test which showed central adrenal deficiency, but her brain magnetic resonance imaging did not reveal any pituitary or sellar changes. A diagnosis of nivolumab induced hypophysitis was made, based on clinical grounds and hormonal profile and she was started on oral steroids. She responded dramatically to this steroidal therapy within four weeks of its initiation and her immunotherapy with nivolumab was restarted.

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.

Multiple endocrinopathies, hypercalcaemia and pancreatitis following combined immune checkpoint inhibitor use- case report and review of literature.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are a novel class of oncological agents which are used to treat a number of malignancies. To date seven agents have been approved by the Food and Drug Administration (FDA) to treat both solid and haematological malignancies. Despite their efficacy they have been associated with a number of endocrinopathies. We report a unique case of hypophysitis, thyroiditis, severe hypercalcaemia and pancreatitis following combined ICI therapy. CASE PRESENTATION: A 46-year old Caucasian female with a background history of malignant melanoma and lung metastases presented to the emergency department with lethargy, nausea, palpitations and tremors. She had been started on a combination of nivolumab and ipilimumab 24 weeks earlier. Initial investigations revealed thyrotoxicosis with a thyroid stimulating hormone (TSH) of < 0.01 (0.38-5.33) mIU/L, free T4 of 66.9 (7-16) pmol/.L. TSH receptor and thyroperoxidase antibodies were negative. She was diagnosed with thyroiditis and treated with a beta blocker. Six weeks later she represented with polyuria and polydipsia. A corrected calcium of 3.54 (2.2-2.5) mmol/l and parathyroid hormone (PTH) of 9 (10-65) pg/ml confirmed a diagnosis of non-PTH mediated hypercalcaemia. PTH-related peptide and 1, 25-dihydroxycholecalciferol levels were within the normal range. Cross-sectional imaging and a bone scan out ruled bone metastases but did reveal an incidental finding of acute pancreatitis - both glucose and amylase levels were normal. The patient was treated with intravenous hydration and zoledronic acid. Assessment of the hypothalamic-pituitary-adrenal (HPA) axis uncovered adrenocorticotrophic hormone (ACTH) deficiency with a morning cortisol of 17 nmol/L. A pituitary Magnetic Resonance Image (MRI) was unremarkable. Given her excellent response to ICI therapy she remained on ipilimumab and nivolumab. On follow-up this patient's thyrotoxicosis had resolved without anti-thyroid mediations - consistent with a diagnosis of thyroiditis secondary to nivolumab use. Calcium levels normalised rapidly and remained normal. ACTH deficiency persisted, and she is maintained on oral prednisolone. CONCLUSION: This is a remarkable case in which ACTH deficiency due to hypophysitis; thyroiditis; hypercalcaemia and pancreatitis developed in the same patient on ipilimumab and nivolumab combination therapy. We postulate that hypercalcaemia in this case was secondary to a combination of hyperthyroidism and secondary adrenal insufficiency.

The imaging of immunotherapy-related hypophysitis and other pituitary lesions in oncology patients.

Immunotherapy has revolutionised the treatment of metastatic disease from a variety of different primaries, but is frequently associated with immune-related adverse events. This review illustrates the imaging features of immunotherapy-related hypophysitis (IH) and some of the important differential diagnoses in oncology patients. The key radiological characteristic of IH is diffuse, modest enlargement of the pituitary gland with temporal evolution attributable to immunotherapy. Pituitary enlargement is transient, and the gland size returns to baseline size or smaller within months. IH is usually associated with homogeneous enhancement of the pituitary gland, and the pituitary stalk may be thickened. Larger pituitary size, deviation of the pituitary stalk, the presence of a discrete lesion surrounding by normal pituitary tissue, sellar expansion, and clival invasion are not typical of IH and suggest alternate diagnoses. On integrated 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography (PET)/computed tomography (CT), a transient increase in the metabolic activity of the pituitary gland with subsequent decline to background activity is also suggestive of IH. We suggest that the sella is assessed routinely on imaging performed in the first 6 months after commencing immunotherapy to detect subtle changes. Radiologists should also be aware of features that either support a diagnosis of IH or suggest alternate diagnoses.

When polyuria does not stop: a case report on an unusual complication of hantavirus infection.

BACKGROUND: The clinical features, course and outcome of hantavirus infection is highly variable. Symptoms of the central nervous system may occur, but often present atypically and diagnostically challenging. Even though the incidence of hantavirus infection is increasing worldwide, this case is the first to describe diabetes insipidus centralis as a complication of hantavirus infection in the Western world. CASE PRESENTATION: A 49-year old male presenting with severe headache, nausea and photophobia to our neurology department was diagnosed with acute haemorrhage in the pituitary gland by magnetic resonance imaging. In the following days, the patient developed severe oliguric acute kidney failure. Diagnostic workup revealed a hantavirus infection, so that the pituitary haemorrhage resulting in hypopituitarism was seen as a consequence of hantavirus-induced hypophysitis. Under hormone replacement and symptomatic therapy, the patient's condition and kidney function improved considerably, but significant polyuria persisted, which was initially attributed to recovery from kidney injury. However, water deprivation test revealed central diabetes insipidus, indicating involvement of the posterior pituitary gland. The amount of urine production normalized with desmopressin substitution. CONCLUSION: Our case report highlights that neurological complications of hantavirus infection should be considered in patients with atypical clinical presentation.

MRI Findings of Immune Checkpoint Inhibitor-Induced Hypophysitis: Possible Association with Fibrosis.

BACKGROUND AND PURPOSE: Hypophysitis is one of the well-known adverse effects of immune checkpoint inhibitors. Immune checkpoint inhibitor-induced hypophysitis frequently causes irreversible hypopituitarism, which requires long-term hormone replacement. Despite the high frequency and clinical significance, characteristic MR imaging findings of immune checkpoint inhibitor-induced hypophysitis have not been established. In the present study, we aimed to review and extract the MR imaging features of immune checkpoint inhibitor-induced hypophysitis. MATERIALS AND METHODS: This retrospective international multicenter study comprised 20 patients with melanoma who were being treated with immune checkpoint inhibitors and clinically diagnosed with immune checkpoint inhibitor-induced hypophysitis. Three radiologists evaluated the following MR imaging findings: enlargement of the pituitary gland and stalk; homogeneity of enhancement of the pituitary gland; presence/absence of a well-defined poorly enhanced area and, if present, its location, shape, and signal intensity in T2WI; and enhancement pattern in contrast-enhanced dynamic MR imaging. Clinical symptoms and hormone levels were also recorded. RESULTS: Enlargement of the pituitary gland and stalk was observed in 12 and 20 patients, respectively. Nineteen patients showed poorly enhanced lesions (geographic hypoenhancing lesions) in the anterior lobe, and 11 of these lesions showed hypointensity on T2WI. Thyrotropin deficiency and corticotropin deficiency were observed in 19/20 and 12/17 patients, respectively, which persisted in 12/19 and 10/12 patients, respectively, throughout the study period. CONCLUSIONS: Pituitary geographic hypoenhancing lesions in the anterior lobe of the pituitary gland are characteristic and frequent MR imaging findings of immune checkpoint inhibitor-induced hypophysitis. They reflect fibrosis and are useful in distinguishing immune checkpoint inhibitor-induced hypophysitis from other types of hypophysitis/tumors.

Central diabetes insipidus related to anti-programmed cell-death 1 protein active immunotherapy.

Cancer immunotherapy is a breakthrough strategy entwined with toxicity. Immune-related hypophysitis is conventionally considered distinctive of cytotoxic T-lymphocyte antigen 4 (CTLA-4) inhibitors. Immune-related central diabetes insipidus (CDI) is exceptional. CDI rarely manifests as hypernatremia, which is almost always euvolemic. We report a 71-years-old male patient with advanced lung cancer who experienced severe chronic hypernatremia presented as alterations in mental status five months after initiation of treatment with the anti-PD-1 checkpoint inhibitor nivolumab. Combination of persistenthypernatremia, polyuria, high plasma osmolality and hyposthenuria raised suspicion of diabetes insipidus, prompting measurement of serum concentration of arginine vasopressin(AVP). The inappropriately undetectable serum levels of AVP confirmed central diabetes insipidus (CDI). Nivolumab-related hypophysitis was recognized as possible cause of CDI. Further hormonal assessment excluded any endocrinopathy indicating disorder of posterior pituitary. Pituitary MRI was normal with persistence of hyperintensity of posterior pituitary on T1-weighted images (bright spot). The patient was scheduled to receive 1-deamino-8-D-arginine vasopressin (DDAVP), but he died suddenly due to cardiac arrest before initiation of treatment. Our report describes the first case of nivolumab related CDI, building on existing literature through: (I) underscoring hypovolemic hypernatremia as CDI manifestation; (ii) bringing into spotlight the rare anti-PD-1 treatment related hypophysitis; (iii) enriching the limited evidence on immune-related CDI. Increased awareness of nivolumab related CDI will enable prompt recognition and therapeutic intervention.

[Checkpoint inhibitors-induced hypophysitis]. / Hypophysites induites par les immunothérapies anti-néoplasiques.

Checkpoint inhibitors immunotherapy is more and more prescribed in oncology, causing new immune related endocrine adverse events. Hypophysitis occurs in approximately 10 % of patients treated with anti-CTLA4. It occurs two to three months after initiation of the immunotherapy. The initial presentation is characterized, in typical forms, by the association of headache, asthenia and hyponatremia. Hormonal exploration usually shows ACTH, gonadotropic and thyrotropic deficiencies. ACTH deficiency may be life-threatening and requires urgent supplementation, without awaiting for biological results. MRI is warranted in order to exclude differential diagnoses, such as pituitary metastases. Hypophysitis induced by anti-PD1/PDL1 seems to be a different nosologic entity characterized by a later onset and a less symptomatic presentation. Biologically ACTH deficiency seems to be constant and permanent, and often isolated. Treatment requires high-dose steroids only in case of severe tumor syndrome (resistant headache, visual disturbance) or acute decompensation of ACTH deficiency. Patients always need lifelong hormonal supplementation of pituitary deficits and must be followed and educated specifically. Immunotherapy can be delayed during the acute phase, but can be secondarily continued if there is an oncological benefit. As it is a pauci-symptomatic but potentially life-threatening complication, biological screening must be systematic in patients treated with checkpoint inhibitors.