Lymphocytic infundibuloneurohypophysitis: long-term follow-up of a case cured with glucocorticoid

Central diabetes insipidus with anti-rabphilin-3A antibody positivity causing hypovolemic shock after resection of tumorous lesions in the pelvic cavity

A 36-year-old female was pointed out to have liver enzyme elevation by routine health checkup. Subsequent contrast-enhanced CT scan identified gigantic uterine fibroids and retroperitoneal tumor. She was referred to the gynecologist at JA Toride Medical Center and planned to undergo a uterus enucleation and biopsy of the retroperitoneal tumor. The surgery was conducted without any troubles. After the surgery, the patient presented polyuria with urine volume 10-20 L a day and developed hypovolemic shock. Laboratory test revealed hypotonic urine and hypernatremia. Arginine vasopressin (AVP) loading test suggested shortage of endogenous vasopressin. Since the subcutaneous administration of AVP was not sufficient to control the urine volume, continuous intravenous infusion of AVP was initiated. After achieving hemodynamic stability, the treatment was switched to oral desmopressin. MRI finding indicated attenuation of high signal in posterior pituitary in T1 weighted image while neither enlargement of pituitary nor thickening of pituitary stalk was indicated by enhanced MRI. Hypertonic salt solution test indicated no responsive elevation of AVP, confirming the diagnosis of central diabetes insipidus (CDI). Her anterior pituitary function was preserved. Only anti-rabphilin-3A antibody was found positive in the serum of the patient, while other secondary causes for CDI were denied serologically and radiologically. Hence, lymphocytic infundibuloneurohypophysitis　(LINH) was suspected as the final diagnosis. Hormonal replacement therapy by nasal desmopressin was continued and the patient managed to control her urine volume. In cases of CDI considered idiopathic with conventional examinations, anti-rabphilin-3A antibody may be a clue for determining the cause as LINH.

Autoimmune diabetes insipidus

Once central diabetes insipidus (CDI) has been diagnosed, every effort should be made to reveal its underlying cause. Autoimmune CDI should be considered in the differential diagnosis of idiopathic CDI and also of mass lesions of the sella region. An autoimmune etiology of CDI was first suggested in 1983 by the detection of autoantibodies to hypothalamic vasopressin-producing cells (AVPcAb) in adults and also in children with the disease, using the indirect immunofluorescence test. The major autoantigen for autoimmune CDI has now been recognized as rabphilin-3A, a protein of secretory vesicles of the neurohypophyseal system. The detection of autoantibodies to rabphilin-3A by Western blotting or of AVPcAb provides strong evidence for the diagnosis of autoimmune CDI. Autoimmune CDI is recognized mostly in patients who had also been diagnosed with endocrine autoimmune disorders. The radiological and morphological correlate with autoimmune DI is lymphocytic infundibuloneurohypophysitis (LINH) as detected by magnetic resonance imaging and biopsies that show massive infiltration of the posterior pituitary and the infundibulum with lymphocytes and some plasma cells, and fibrosis in the later stages of the disease. LINH may be associated with lymphocytic anterior hypophysitis. Both may either appear spontaneously or on treatment with immune checkpoint inhibitors.

Clinical presentation and outcome of children with central diabetes insipidus associated with a self-limited or transient pituitary stalk thickening, diagnosed as infundibuloneurohypophysitis

OBJECTIVE

Despite lymphocytic or autoimmune infundibuloneurohypophysitis (INH) is an increasingly recognized aetiology in children with central diabetes insipidus (CDI); clinical data on epidemiology (clinical evolution, predisposing factors, complications), diagnosis and management of this entity are limited and mostly based on published case reports. The aim of this study was to gain a broader insight in the natural history of this disease by analysing the clinical presentation, radiological pituitary stalk changes, associated autoimmunity and hormonal deficiencies in children with CDI and a self-limiting or transient stalk thickening (ST), diagnosed as autoimmune infundibuloneurohypophysitis, during the last 15 years in four Belgian university hospitals.

DESIGN AND PATIENTS

The medical files of nine CDI patients with a ST at initial presentation and no signs of Langerhans cell histiocytosis or germinoma at presentation and/or during follow-up of more than 1.5 years were reviewed.

RESULTS

Age at presentation ranged from 3 to 14 years. Two patients had a positive family history of autoimmunity. Three children presented with associated growth failure, two with nausea and one with long-standing headache. Median maximal diameter of the stalk was 4.6 mm (2.7-10 mm). Four patients had extra-pituitary brain anomalies, such as cysts. One patient had central hypothyroidism, and another had a partial growth hormone deficiency at diagnosis. Within a mean follow-up of 5.4 (1.5-15) years, stalk thickening remained unchanged in two patients, regressed in one and normalized in six children. CDI remained in all, while additional pituitary hormone deficiencies developed in only one patient.

CONCLUSIONS

In this series of children INH with CDI as initial presentation, CDI was permanent and infrequently associated with anterior pituitary hormone deficiencies, despite a frequent association with nonstalk cerebral lesions.

Lymphocytic infundibulo-neurohypophysitis: a clinical overview

Lymphocytic infundibulo-neurohypophysitis is an uncommon inflammatory disorder postulated to be autoimmune in origin. Because of the location of inflammation, it selectively affects the posterior lobe of the pituitary (neurohypophysis) and pituitary stalk (infundibulum). The most common presentation is central diabetes insipidus. Although the definitive diagnosis is established histologically by a pituitary biopsy, radiological imaging can be valuable in diagnosing this condition. In this paper, we provide an overview of the pathophysiology, investigations, management, and outcomes of lymphocytic infundibulo-neurohypophysitis.

Subclinical diabetes insipidus

Subclinical central diabetes insipidus (CDI) can be the outcome of a number of diseases that affect the hypothalamus-infundibulum-post hypophysis axis. One of the most common forms of subclinical CDI is linked to an autoimmune pathogenesis even if other causes may be also responsible. Among these, pregnancy, traumatic and surgical brain injury and some infiltrative, vascular, infectious and neoplastic diseases have been reported with increasing frequency. The natural history of autoimmune CDI seems to evolve through 4 functional stages according to the presence of antibodies to vasopressin-secreting cells (AVPcAb) and the relationship between their behavior overtime, the variations of posterior pituitary function and the characteristics of hypothalamic-hypophyseal region on magnetic resonance imaging. This staging is of crucial importance for the therapeutic strategy, taking into account that some stages could be still reversible. Several medical treatments have been suggested to interrupt the progression toward clinical CDI but the results are still discussed.

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.

Lymphocitic infundibulo-neurohypophysitis mimicking a pituitary adenoma

A rare case of infundibulo-neurohypophysitis mimicking a pituitary adenoma is presented. A 69-years-old female patient developed polyuria and polydipsia. Laboratory analysis revealed central diabetes insipidus. No hormonal abnormalities. Cranial-magnetic resonance imaging (MRI) showed a left sided mass in the adenohypophysis presuming a pituitary adenoma. The mass had contact to both internal carotids. Admission to our department for neurosurgical treatment followed. Ophthalmologic examination and neurological examination yielded normal findings. A second MRI focussing on the sellar-region showed a left-sided (T2-MRI.hyperintense), distended adenohypophysis, without contrast enhancement in T1. The stalk appeared thickened. T1-weighted sequences of the neurohypophysis showed loss of signal intensity. We diagnosed an infundibulo-neurohypophysitis and abstained from surgical removal. The patient was discharged under treatment with corticosteroids and desmopressin. Hypophysitis is rare and shows special clinical characteristics. Despite defined radiological features to differentiate between hypophysitis and adenoma the possibility of misdiagnosis, and unnecessary surgical procedures, should always kept in mind.