Lymphocytic hypophysitis (LYH) is an uncommon autoimmune disease in which the pituitary gland is infiltrated by lymphocytes, plasma cells and macrophages and its function is usually impaired. It has to be suspected in pregnant women and in women with recent delivery presenting with hyperprolactinemia, headache, visual field alterations and changes of one or more pituitary hormone secretions with secondary impairment of related peripheral target glands, especially when associated with other autoimmune endocrine or non-endocrine disorders. It can also occur less frequently in prepubertal or post-menopausal women and in men. Headache, visual field impairment and more rarely diplopia are due to extrasellar pituitary enlargement with optic chiasma compression and/or to invasion of cavernous sinuses. Among the 'isolated' pituitary hormone deficiencies, ACTH deficit is usually the earliest and most frequent hormonal impairment and in rare cases can induce an acute secondary hyposurrenalism as the first sign of the disease, with high mortality in affected patients. Histopathological findings from pituitary biopsy show lymphoplasmacytic infiltrate with lymphoid aggregates surrounding atropic acini of pituitary cells; immunohistochemical analysis shows numerous mast cells randomly distributed and also localized in the vicinity of capillaries, suggesting a possible influence on capillary permeability and angiogenesis, thus favoring the inflammatory and immunological aggression against pituitary cells. Nuclear magnetic resonance imaging shows uniform sellar floor depression and an extrasellar symmetrical pituitary enlargement, usually displacing the optic chiasma, which shows a rapid homogeneous enhancement after gadolinium also involving the adjacent dura (dural tail). Antipituitary antibodies have been detected in several patients with LYH but their role needs to be clarified. Since a possible spontaneous remission can occur, a careful follow-up is required in subclinical patients without important hyposurrenalism or symptomatic extrasellar expansion. Medical (immunosuppressive, replacement and antiprolactinemic) and neurosurgical (decompression) treatments are needed in clinical symptomatic patients.

Objective: Traumatic brain injury (TBI) is a devastating public health problem that may result in hypopituitarism. However, the mechanisms responsible for hypothalamic–pituitary dysfunction due to TBI are still unclear. Although the antibodies against neurons have been demonstrated in injured animal studies, investigations regarding the occurrence of antipituitary antibodies (APAs) in patients with TBI are lacking in the literature. In order to investigate whether autoimmune mechanisms could play a role in the pituitary dysfunction after TBI, we have planned this study aimed at investigating the presence of APA at the third year of TBI and association between the TBI-induced hypopituitarism and APA.Patients and design: Twenty-nine (25 males and 4 females; age 36.5±2.3 years) patients who had completed a 3-year follow-up after TBI were included in the present study. APA and pituitary function were evaluated in all the patients 3 years after TBI; moreover, APAs were tested also in sera of 60 age-/sex-matched normal controls. The APAs were investigated by an indirect immunofluorescence method.Results: APAs were detected in 13 out of the 29 TBI patients (44.8%), but in none of the normal controls. Pituitary dysfunction development ratio was significantly higher in APA-positive patients (46.2%) when compared with APA-negative ones (12.5%;P=0.04). There was a significant association between APA positivity and hypopituitarism due to TBI (odds ratio: 2.25, 95% confidence intervals 1.1–4.6). Moreover, there was a significant positive correlation (r=0.74,P=0.004) between APA titer ratio and peak GH response to GHRH+GH related peptide (GHRP)-6 test, suggesting that high APA titers were associated with low GH response to GHRH+GHRP-6 test.Conclusions: This study shows for the first time the presence of the APA in TBI patients 3 years after head trauma. Moreover, present investigation indicates preliminary evidence that APA may be associated with the development of TBI-induced pituitary dysfunction, thus suggesting that autoimmunity may contribute in the development of TBI-induced hypopituitarism. The presence of the association between APA and TBI-induced hypopituitarism may provide a new point of view in this field and promote further clinical and experimental studies.

Traumatic brain injury (TBI) has been recently recognized as a common cause of pituitary dysfunction. However, there are not sufficient numbers of prospective studies to understand the natural history of TBI induced hypopituitarism. The aim was to report the results of five years' prospective follow-up of anterior pituitary function in patients with mild, moderate and severe TBI. Moreover, we have prospectively investigated the associations between TBI induced hypopituitarism and presence of anti-hypothalamus antibodies (AHA) and anti-pituitary antibodies (APA). Twenty five patients (20 men, five women) were included who were prospectively evaluated 12 months and five years after TBI, and 17 of them also had a third-year evaluation. Growth hormone (GH) deficiency is the most common pituitary hormone deficit at one, three, and five years after TBI. Although most of the pituitary hormone deficiencies improve over time, there were substantial percentages of pituitary hormone deficiencies at the fifth year (28% GH, 4% adrenocorticotropic hormone [ACTH], and 4% gonadotropin deficiencies). Pituitary dysfunction was significantly higher in strongly AHA- and APA-positive (titers ≥1/16) patients at the fifth year. In patients with mild and moderate TBI, ACTH and GH deficiencies may improve over time in a considerable number of patients but, although rarely, may also worsen over the five-year period. However in severe TBI, ACTH and GH status of the patients at the first year evaluation persisted at the fifth year. Therefore, screening pituitary function after TBI for five years is important, especially in patients with mild TBI. Moreover, close strong associations between the presence of high titers of APA and/or AHA and hypopituitarism at the fifth year were shown for the first time.

Central diabetes insipidus (CDI) is a rare hypothalamus-pituitary disease due to the deficiency of arginine vasopressin (AVP) synthesis from the hypothalamus and/or secretion from the neurohypophysis. The etiology of CDI is unknown in over one third of cases, classified as idiopathic CDI. The aim of this study was 2-fold: 1) to evaluate the occurrence of circulating autoantibodies to AVP-secreting cells (AVPcAb), and 2) to correlate it to clinical (sex, age of disease onset, disease duration, and degree), immunological (clinical history of autoimmune diseases and presence of related organ-specific autoantibodies), and radiological features (neurohypophyseal bright spot, pituitary stalk thickening, and empty sella) in a large cohort of patients with apparently idiopathic CDI or CDI of known etiology. To this purpose, 150 patients with CDI were studied: 64 idiopathic, 6 familial, 12 associated to granulomatous diseases, and 68 secondary to cranial trauma, tumor, or surgery. AVPcAb were measured by an indirect immunofluorescence method. AVPcAb were found in 23.3% of CDI patients: 21 idiopathic (32.8%) and 14 nonidiopathic (16.3%; χ² = 13.1; P < 0.001). AVPcAb were independently associated with age less than 30 yr at disease onset (P = 0.001) in patients with idiopathic CDI and with history of autoimmune diseases (P = 0.006 and P = 0.02, respectively) and radiological evidence of pituitary stalk thickening (P = 0.02 and P = 0.003, respectively) in both idiopathic and nonidiopathic CDI. The likelihood of autoimmunity in one patient with apparently idiopathic CDI with age of disease onset less than 30 yr was 53%, it increased to 91% when history of autoimmune diseases was associated and to 99% when pituitary stalk thickening was further associated. In conclusion, autoimmunity is associated with one third of patients with apparently idiopathic CDI, which should therefore be classified as autoimmune CDI. Autoimmune CDI is highly likely in young patients with a clinical history of autoimmune diseases and radiological evidence of pituitary stalk thickening. Conversely, autoimmunity probably represents an epiphenomenon in patients with nonidiopathic CDI.