Hypophysitis occurs in up to 10% of patients treated with immune-checkpoint inhibitors (ICIs). MRI shows no abnormalities of the pituitary gland in one third of patients. A delayed diagnosis increases the risk for life-threatening adrenal crisis, underscoring the need for early detection. This study evaluates the diagnostic accuracy FDG PET/CT in detecting ICI-induced hypophysitis in a cohort of melanoma patients. Patients with metastatic melanoma and ICI-induced hypophysitis, who underwent FDG PET/CT 90 days before to 10 days after diagnosis, were compared with an age- and sex-matched control group of patients undergoing ICI treatment without signs of hypophysitis. The ratio of SUV max of the pituitary gland to the SUV mean of the blood pool (target-to-background ratio [TBR]) was calculated. Diagnostic accuracy of the TBR was assessed using area under the receiver operating characteristics curve analysis. A total of 28 patients was included. The majority of patients with hypophysitis received ipilimumab/nivolumab (64.3%, 9/14). Visual assessment of the TBR distribution demonstrated a positive correlation with decreasing time to diagnosis. To evaluate diagnostic performance, only patients with FDG PET/CT 50 days before to 8 days after diagnosis (11/14) were included. TBR was significantly higher in these compared with the control group (median [interquartile range], 2.78 [2.41] vs 1.59 [0.70], respectively; P = 0.034). A sensitivity of 72.7% and a specificity of 90.9% were achieved at a TBR threshold of 2.41 (area under the receiver operating characteristics curve = 0.769). Our findings suggest that, in patients undergoing ICI treatment for metastatic melanoma, a pituitary TBR of approximately 2.4 may indicate impending ICI-induced hypophysitis.

Immune checkpoint inhibitors (ICIs), as novel antitumor drugs, have been widely used in the clinic and have shown good antitumor effects. However, their widespread use has also led to the emergence of various immune-related adverse events (IrAEs). Hypophysitis is a rare but serious IrAE. Due to its complex and changeable clinical manifestations, hypophysitis may be easily overlooked, leading to delayed diagnosis and treatment. A 68-year-old male patient was diagnosed with bladder cancer (T2bNXM0) in October 2021. He received two cycles of immunotherapy with sintilimab and chemotherapy with gemcitabine and cisplatin (GC). One month after the second treatment, he gradually developed recurrent fever, anorexia, drowsiness, and delirium. Laboratory examination revealed hyponatremia, decreased adrenocorticotropic hormone, and hypocortisolemia. The pituitary MRI showed no abnormality. The patient was diagnosed with immunotherapy-induced hypophysitis (IH) caused by sintilimab, leading to downstream endocrine disorders. With hormone replacement therapy, he was in a good mood, had a good appetite, and made an overall recovery. Immunotherapy-induced hypophysitis (IH) can result in a severe adrenal crisis, and prompt recognition and diagnosis are crucial. Clinicians must remain vigilant for the possibility of IH in patients who exhibit recurrent fever, anorexia, cognitive decline, and personality changes following ICI treatment. It is imperative to consider this diagnosis early to initiate appropriate management promptly.

Immune checkpoint inhibitors represent a hopeful and emerging group of medications employed in the regulation of the immune response against cancer, displaying tremendous potential in cancer treatment. However, the administration of these drugs has been linked to the occurrence of adverse events, among which hypophysitis appears to be a prevailing complication affecting a substantial number of patients. Given the potential gravity of this condition, it is strongly recommended to actively monitor hormone levels throughout the treatment process, allowing for the prompt detection and provision of appropriate therapeutic measures. The present study showcases a case involving a 72-year-old individual afflicted with both bladder cancer and prostate cancer, who subsequently developed autoimmune hypophysitis and secondary adrenocortical insufficiency following the administration of programmed death protein 1 (PD-1) inhibitors.

A Caucasian man in his 60s with recent diagnosis of metastatic renal cell carcinoma presented to the emergency department with a 5-day history of severe polyuria, polydipsia and fatigue and 1-day history of confusion, abdominal pain, nausea and vomiting. Investigations revealed an overlap of diabetic ketoacidosis (DKA) and hyperosmolar hyperglycaemic state (HHS). He had received the first dose of immunotherapy with nivolumab and ipilimumab 3 weeks prior to this attendance. New-onset type 1 diabetes (T1DM) was confirmed based on the clinical features at presentation, seropositivity for glutamic acid decarboxylase antibodies and significant insulin deficiency. He is currently on a multiple daily injections of insulin and uses intermittent-scanned glucose monitoring. Given the irreversible impact on beta-cell function and clinical response with insulin resulting in improved diabetes control, immunotherapy was resumed for his metastatic cancer with good radiological response. Although rare, new-onset T1DM can present with DKA and HSS overlap after a single dose of nivolumab/ipilimumab in individuals without pre-existing history of diabetes. Although rare, new onset of T1DM after immunotherapy can present with DKA and HSS overlap after a single dose of nivolumab/ipilimumab in individuals without pre-existing history of diabetes and normal glycaemic parameters. Due to the irreversible destruction of beta-cells, treatment with steroids is not indicated in contrast to other settings such as immunotherapy-induced hypophysitis. Presence of low c-peptide levels post-acute presentation is indicative of an irreversible impact on beta-cell function and supports resuming immunotherapy given the significant benefits on cancer prognosis. Clinicians must maintain a high index of suspicion in regards to diagnosis and management of new-onset type 1 diabetes and advice patients on reporting symptoms suggestive of diabetes and/or diabetes-related hyperglycaemic emergencies.

Hypophysitis is defined as inflammation of the pituitary gland that is primary or secondary to a local or systemic process. Differential diagnosis is broad (including primary tumors, metastases, and lympho-proliferative diseases) and multifaceted. Patients with hypophysitis typically present with headaches, some degree of anterior and/or posterior pituitary dysfunction, and enlargement of pituitary gland and/or stalk, as determined by imaging. Most hypophysitis causes are autoimmune, but other etiologies include inflammation secondary to sellar tumors or cysts, systemic diseases, and infection or drug-induced causes. Novel pathologies such as immunoglobulin G4-related hypophysitis, immunotherapy-induced hypophysitis, and paraneoplastic pituitary-directed autoimmunity are also included in a growing spectrum of this rare pituitary disease. Typical magnetic resonance imaging reveals stalk thickening and homogenous enlargement of the pituitary gland; however, imaging is not always specific. Diagnosis can be challenging, and ultimately, only a pituitary biopsy can confirm hypophysitis type and rule out other etiologies. A presumptive diagnosis can be made often without biopsy. Detailed history and clinical examination are essential, notably for signs of underlying etiology with systemic manifestations. Hormone replacement and, in selected cases, careful observation is advised with imaging follow-up. High-dose glucocorticoids are initiated mainly to help reduce mass effect. A response may be observed in all auto-immune etiologies, as well as in lymphoproliferative diseases, and, as such, should not be used for differential diagnosis. Surgery may be necessary in some cases to relieve mass effect and allow a definite diagnosis. Immunosuppressive therapy and radiation are sometimes also necessary in resistant cases.