Central diabetes insipidus induced by temozolomide: A report of two cases

INTRODUCTION

Central diabetes insipidus is a heterogeneous condition characterized by decreased release of antidiuretic hormone by the neurohypophysis resulting in a urine concentration deficit with variable degrees of polyuria. The most common causes include idiopathic diabetes insipidus, tumors or infiltrative diseases, neurosurgery and trauma. Temozolomide is an oral DNA-alkylating agent capable of crossing the blood-brain barrier and used as chemotherapy primarily to treat glioblastoma and other brain cancers.

CASES

Two men (aged 38 and 54 years) suddenly developed polyuria and polydispsia approximately four weeks after the initiation of temozolomide for a glioblastoma. Plasma and urine parameters demonstrated the presence of a urinary concentration defect.

MANAGEMENT

The clinical and laboratory abnormalities completely resolved with intranasal desmopressin therapy, allowing the continuation of temozolomide. The disorder did not relapse after cessation of temozolomide and desmopressin and relapsed in one patient after rechallenge with temozolomide.

DISCUSSION

Our report highlights the importance of a quick recognition of this exceptional complication, in order to initiate promptly treatment with desmopressin and to maintain therapy with temozolomide.

Diabetes Insipidus: An Update

The differential diagnosis of diabetes insipidus involves the distinction between central or nephrogenic diabetes insipidus and primary polydipsia. Differentiation is important because treatment strategies vary; the wrong treatment can be dangerous. Reliable differentiation is difficult especially in patients with primary polydipsia or partial forms of diabetes insipidus. New diagnostic algorithms are based on the measurement of copeptin after osmotic stimulation by hypertonic saline infusion or after nonosmotic stimulation by arginine and have a higher diagnostic accuracy than the water deprivation test. Treatment involves correcting preexisting water deficits, but is different for central diabetes insipidus, nephrogenic diabetes insipidus, and primary polydipsia.

Pituitary sellar spine in a pediatric patient with diabetes insipidus

A sellar spine is a midline bony spur arising from the ventral aspect of the dorsum sellae. Representing a remnant of the anterior notochord, it is often an incidental finding and thought to be of no clinical significance. However, it has recently been suggested that a potential association may exist between sellar spine and pediatric pituitary endocrinopathies, possibly caused by deformation of the developing pituitary gland by the sellar spine. To our knowledge, this is the first case report demonstrating an association between sellar spine and clinical diabetes insipidus.

Postoperative Hormonal Outcomes in Patients with Large and Giant Non-functioning Pituitary Adenomas

Objective and Aims

To study hormonal axis (HA) dysfunction pre-operatively and at three months after surgery in patients with large (>3 cms) (Hardy's grade C) and giant (>4 cms) nonfunctioning pituitary adenomas (NFPA).

Methods

One hundred thirty nine patients operated between 2006 and 2017, with 3 months post-operative hormonal evaluation, were included in this retrospective study. HA damage was categorized as 0 to 3 based on number of axes (thyrotroph, corticotroph and gonadotroph) that were affected. Risk factors studied for HA dysfunction before and after surgery included duration of symptoms, size of tumor, diabetes mellitus, hypertension and extent of resection.

Results

Preoperatively 45 (32.3%) had no axis involvement, 34 (24.4%), 36 (25.8%) and 24 (17.2%) had one, two and three axes involvement respectively. Thyrotroph axis was affected in most patients. Tumor volume had significant correlation with preoperative pituitary dysfunction (P < 0.000). Post-operatively HA function remained same in 100 (72%), improved in only 7 (5%) and worsened in 32 (23%) of the patients. Of the 3 HA, corticotroph function worsened in most patients. None of the patients who had dysfunction in all three axes had improvement after surgery. No significant risk factors were associated with post-operative pituitary function outcomes. Persistent diabetes insipidus was noted in six (4.3%) patients.

Conclusion

Pre-operatively anterior pituitary dysfunction is noted in nearly two-thirds of patients with large and giant NFA. Tumor volume >15 cc had significant correlation with pre-operative panhypopituitarism. Post-operatively, pituitary function remains the same in nearly three quarters of the patients. No significant risk factors were found for post-operative hormonal outcomes.

Postoperative management of patients with pituitary tumors submitted to pituitary surgery. Experience of a Spanish Pituitary Tumor Center of Excellence

There is a lack of evidence on timing, frequency, and duration of postoperative endocrine, radiologic, and ophthalmologic assessments that should be performed after pituitary surgery (PS). However, it is known that careful optimization of treatment and follow-up strategies as well as a multidisciplinary approach may have a significant impact on long-term outcomes, improving surgical results, minimize complications and facilitate their correct treatment if occurring, and optimize the hormonal, ophthalmological, and radiological reassessment throughout the follow-up. Considering that there are no specific guidelines on the postoperative management of patients with pituitary tumors (PT), we present our protocol for the postoperative management of patients with PT. It has been elaborated by the multidisciplinary team of a Spanish Pituitary Tumor Center of Excellence (PTCE) that includes at least one neurosurgeon, ENT, neuroradiologist, neuro-ophthalmologist, endocrine pathologist and endocrinologist specialized in pituitary diseases. We elaborated this guideline with the aim of sharing our experience with other centers involved in the management of PT thereby facilitating the postoperative management of patients submitted to PS.

Diabetes insipidus and syndrome of inappropriate antidiuresis (SIADH) after pituitary surgery: incidence and risk factors

Electrolyte disorders are relatively frequent and potentially serious complications after pituitary surgery. Both DI (diabetes insipidus) and SIADH (syndrome of inappropriate antidiuresis) can complicate and prolong hospital and intensive care unit stay, and the latter may even be preventable. We aim to assess the incidence of both electrolyte disorders and their risk factors. From a prospective registry of patients who underwent endoscopic transnasal transsphenoidal surgery (TSS) for pituitary adenoma, patients with postoperative DI and SIADH were identified. Univariable and multivariable statistics were carried out to identify factors independently associated with the occurrence of either DI or SIADH. A total of 174 patients were included, of which 73 (42%) were female. Mean age was 54 years (range 20-88). During postoperative hospital stay, 13 (7.5%) patients presenting with DI and 11 (6.3%) with SIADH were identified. Patients who developed DI after surgery had significantly longer hospital stays (p = 0.022), as did those who developed SIADH (p = 0.002). Four (2.3%) patients were discharged with a diagnosis of persistent DI, and 2 (1.1%) with the diagnosis of SIADH. At the last follow-up, 5 (2.9%) patients presented with persistent DI, while none of the patients suffered from SIADH. Younger age (odds ratio (OR) 0.97, 95% confidence interval (CI) 0.94-1.01, p = 0.166) and pituitary apoplexy (OR 2.69, 95% CI 0.53-10.65, p = 0.184) were weakly associated with the occurrence of DI. We identified younger age (OR 0.96, 95% CI 0.92-0.99, p = 0.045) and lower preoperative serum sodium (OR 0.83, 95% CI 0.71-0.95, p = 0.008) as independent risk factors for SIADH. Although we found a weak association among age, pituitary apoplexy, and the occurrence of DI, no independent predictor was identified for DI. For postoperative SIADH however, lower age and preoperative serum sodium were identified as significant predictors. None of these findings were sufficiently supported by preexisting literature. Both electrolyte disorders are exquisitely hard to predict preoperatively, and further research into their early detection and prevention is warranted.

Pituitary metastases: presentation and outcomes from a pituitary center over the last decade

PURPOSE

Highlight and characterize manifestations, diagnostic/management approaches and outcomes in a contemporary cohort of patients with pituitary metastases (PM) from a large European pituitary center-over 10 years.

METHODS

Retrospective review of PM cases between 1/2009 and 12/2018. Clinical, laboratory, imaging data at PM detection and during follow-up were analysed.

RESULTS

18 cases were identified (14 females; median age at diagnosis 61.5 years). Most common primary malignancies were lung (39%) and breast (32%). Most frequent presenting manifestation was visual dysfunction (50%). Gonadotrophin, ACTH, TSH deficiency were diagnosed in 85%, 67%, 46% of cases, respectively; diabetes insipidus (DI) was present in 17%. 33% of cases were detected during investigation for symptoms unrelated to PM. PM management included radiotherapy (44%), transsphenoidal surgery (17%), transsphenoidal surgery and radiotherapy (6%) or monitoring only (33%). One-year survival was 49% with median survival from PM detection 11 months (range 2-47).

CONCLUSIONS

In our contemporary series, clinical presentation of PM has evolved; we found increased prevalence of anterior hypopituitarism, decreased rates of DI and longer survival compared with older literature. Increased availability of diagnostic imaging, improvements in screening and recognition of pituitary disease and longer survival of patients with metastatic cancer may be contributing factors.

Management of endocrine conditions at the end of life

An important facet to end-of-life care is deprescribing. This can be challenging when reviewing life-sustaining endocrine medications but, unlike for diabetes, there is no national guidance to support patients and clinicians faced with care planning. This article reviews the limited current evidence to highlight areas for further discussion and research with the aim of moving towards consensus opinion. Discontinuation of certain endocrine medications, including corticosteroids, desmopressin and levothyroxine, is likely to precipitate an 'endocrine-driven mechanism of death', while it may be reasonable to discontinue other endocrine medications without the risk of hastening death or causing unnecessary symptoms. However, the over-arching theme should be that early discussion with patients regarding conversion or discontinuation of endocrine medications or monitoring is central to care planning.

Transient water-electrolyte disturbance after hemispherotomy in young infants with epileptic encephalopathy

PURPOSE

This study aimed to elucidate the clinical features of water-electrolyte disturbance (WED) as a sequela of hemispherotomy.

METHODS

We performed a retrospective chart review to identify the clinical features of diabetes insipidus (DI) as a complication in < 12-month-old patients who underwent hemispherectomy or hemispherotomy for severe epilepsy between 2007 and 2018. Central DI was diagnosed if a patient developed polyuria (urine output > 5 mL/kg/h), abnormally high serum osmolality (> 300 mOsm/kg), high serum sodium level (> 150 mEq/L), either abnormally low urine specific gravity (< 1.005) or low urine osmolality (< 300 mOsm/kg) or both, and effective control of polyuria with arginine vasopressin (AVP). The clinical course of post-hemispherotomy WED, complications other than WED, and seizure outcomes were analyzed.

RESULTS

The review identified that 3 of 23 infants developed WED. All patients developed polyuria within 2 days after surgery, with high serum osmolality and hypotonic urine; AVP was effective in treating these symptoms. The clinical course was compatible with central DI. Two patients subsequently developed hyponatremia in a biphasic or triphasic manner. All patients had multiple seizures that were probably related to WED. Two patients developed asymptomatic cerebral sinovenous thrombosis, possibly because of the surgical procedure and dehydration; anticoagulant treatment was provided. All patients were treated for WED for up to 2 months and had no residual pituitary dysfunction.

CONCLUSION

Systemic complications other than intracranial ones can occur in patients who have undergone hemispherotomy. Perioperative systemic management of young infants undergoing this procedure should include careful water and electrolyte balance monitoring.

Multiple endocrinological failures as a clinical presentation of a metastatic lung adenocarcinoma

SUMMARY

Multiple endocrine metastases are a rare but possible complication of lung adenocarcinoma (LAC). Pituitary metastasis is a rare condition with poor clinical expression. Diabetes insipidus (DI) is its most common presenting symptom. Here we report an original case of a pituitary stalk (PS) metastasis from LAC presenting as central DI followed by adrenal insufficiency (AI) from bilateral adrenal metastasis, without known evidence of the primary malignancy. A 45-year-old woman whose first clinical manifestations were polyuria and polydipsia was admitted. She was completely asymptomatic with no cough, no weight loss or anorexia. Chest radiography was normal. Brain MRI showed a thick pituitary stalk (PS). DI was confirmed by water restriction test and treated with vasopressin with great clinical results. Explorations for systemic and infectious disease were negative. Few months later, an acute AI led to discovering bilateral adrenal mass on abdominal CT. A suspicious 2.3 cm apical lung nodule was found later. Histopathological adrenal biopsy revealed an LAC. The patient received systemic chemotherapy with hormonal replacement for endocrinological failures by both vasopressin and hydrocortisone. We present this rare case of metastatic PS thickness arising from LAC associated with bilateral adrenal metastasis. Screening of patients with DI and stalk thickness for lung and breast cancer must be considered. Multiple endocrine failures as a diagnostic motive of LAC is a rare but possible circumstance.

LEARNING POINTS

Adrenal metastasis is a common location in lung adenocarcinoma; however, metastatic involvement of the pituitary stalk remains a rare occurrence, especially as a leading presentation to diagnose lung cancer. The posterior pituitary and the infundibulum are the preferential sites for metastases, as they receive direct arterial blood supply from hypophyseal arteries. Patients diagnosed with diabetes insipidus due to pituitary stalk thickness should be considered as a metastasis, after exclusion of the classical systemic and infectious diseases. The diagnosis of an endocrinological metastatic primary lung adenocarcinoma for patients without respiratory symptoms is often delayed due to a lack of correlation between endocrinological symptoms and lung cancer. The main originality of our case is the concomitant diagnosis of both endocrinological failures, as it was initiated with a diabetes insipidus and followed by an acute adrenal insufficiency.

Diagnosis and treatment of autoimmune and IgG4-related hypophysitis: clinical guidelines of the Japan Endocrine Society

Hypophysitis, which is often accompanied by pituitary dysfunction, is classified into several subtypes based on the cause, histology, and the location of inflammation in the pituitary gland. A definitive diagnosis requires pituitary biopsy, which is invasive, and the process is limited to specialized clinical settings. In this opinion paper, we review the literature associated with hypophysitis, and provide the guidelines of the Japan Endocrine Society for the diagnosis and treatment of autoimmune and IgG4-related hypophysitis.

A homozygote frameshift mutation in OCLN gene result in Pseudo-TORCH syndrome type I: A case report extending the phenotype with central diabetes insipidus and renal dysfunction

Intrauterine infections with the pathogens, including toxoplasmosis, other (syphilis, varicella, mumps, parvovirus, and HIV), rubella, cytomegalovirus, and herpes simplex (TORCH) in susceptible individuals during pregnancy, result in microcephaly, white matter disease, cerebral atrophy, and calcifications in the fetus. Pseudo-TORCH syndrome is an umbrella term, consisting of several syndromes, resultant from different genetic alterations and pathogenetic mechanisms. Band-like calcification with simplified gyration and polymicrogyria (BLC-PMG) is one of these conditions, resultant from biallelic mutations in the OCLN gene, located in the chromosome 5q13.2. OCLN gene encodes occludin, a tight junction protein, which is expressed in the endothelia. The absence of occludin in the developing brain subsequently results in abnormal blood-brain barrier, thus immune-cell mediated tissue damage and cortical malformation. Herein, we present a pediatric patient who had progressive microcephaly, spasticity, multi-drug resistant epilepsy, PMG and intracranial band-type calcifications, accompanied by central diabetes insipidus and renal dysfunction. Whole exome sequencing revealed a homozygote W58Ffs*10 (c.173_194del) frameshift mutation in the OCLN gene. Of 34 BLC-PMG cases with demonstrable OCLN mutations, only three had renal manifestations, which is responsible for the majority of the demises. This is the first case diagnosed as having central diabetes insipidus and responded to desmopressin treatment to the best of our knowledge, however, this clinical improvement could not prevent the patient from renal dysfunction. The patient deceased at four years of age from sepsis, therefore early diagnosis, optimal follow-up for renal involvement and infection prevention measures are necessary for the patients with BLC-PMG.

Diagnosis of central diabetes insipidus using a vasopressin radioimmunoassay during hypertonic saline infusion

Central diabetes insipidus (CDI) is characterized by polyuria and polydipsia caused by impairment of arginine vasopressin (AVP) secretion. In this study, we evaluated plasma AVP concentrations during a hypertonic saline infusion test using a new AVP radioimmunoassay (RIA) which is now available in Japan. Thirteen control subjects, mostly with hypothalamo-pituitary disease but without CDI, and 13 patients with CDI were enrolled in the study. Whether or not subjects had CDI was determined based on the totality of clinical data, which included urine volumes and osmolality. Regression analysis of plasma AVP and serum Na concentrations revealed that the gradient was significantly lower in the CDI group than in the control group. The area under the receiver-operating-characteristic (ROC) curve was 0.99, and the <0.1 gradient cut-off values for the simple regression line to distinguish CDI from control had a 100% sensitivity and a 77% specificity. The ROC analysis with estimated plasma AVP concentrations at a serum Na concentration of 149 mEq/L showed that the area under the ROC curve was 1.0 and the <1.0 pg/mL cut-off values of plasma AVP had a 99% sensitivity and a 95% specificity. We conclude that measurement of AVP by RIA during a hypertonic saline infusion test can differentiate patients with CDI from those without CDI with a high degree of accuracy. Further investigation is required to confirm whether the cut-off values shown in this study are also applicable to a diagnosis of partial CDI or a differential diagnosis between CDI and primary polydipsia.

Incidence and Effect of Diabetes Insipidus in the Acute Care of Patients with Severe Traumatic Brain Injury

BACKGROUND

Literature on diabetes insipidus (DI) after severe traumatic brain injury (TBI) is scarce. Some studies have reported varying frequencies of DI and have showed its association with increased mortality, suggesting it as a marker of poor outcome. This knowledge gap in the acute care consequences of DI in severe TBI patients led us to conceive this study, aimed at identifying risk factors and quantifying the effect of DI on short-term functional outcomes and mortality.

METHODS

We assembled a historic cohort of adult patients with severe TBI (Glasgow Coma Scale ≤ 8) admitted to the intensive care unit (ICU) of a tertiary-care university hospital over a 6-year period. Basic demographic characteristics, clinical information, imaging findings, and laboratory results were collected. We used logistic regression models to assess potential risk factors for the development of DI, and the association of this condition with death and unfavorable functional outcomes [modified Rankin scale (mRS)] at hospital discharge.

RESULTS

A total of 317 patients were included in the study. The frequency of DI was 14.82%, and it presented at a median of 2 days (IQR 1-3) after ICU admission. Severity according to the Abbreviated Injury Scale (AIS) score of the head, intracerebral hemorrhage, subdural hematoma, and skull base fracture was suggested as risk factors for DI. Diagnosis of DI was independently associated death (OR 4.34, CI 95% 1.92-10.11, p = 0.0005) and unfavorable outcome (modified Rankin Scale = 4-6) at discharge (OR 7.38; CI 95% 2.15-37.21, p = 0.0047).

CONCLUSIONS

Diabetes insipidus is a frequent and early complication in patients with severe TBI in the ICU and is strongly associated with increased mortality and poor short-term outcomes. We provide clinically useful risk factors that will help detect DI early to improve prognosis and therapy of patients with severe TBI.

Amyloid-like aggregation of provasopressin

The antidiuretic hormone vasopressin is synthesized as a longer precursor protein. After folding in the endoplasmic reticulum (ER), provasopressin is transported through the secretory pathway, forms secretory granules in the trans-Golgi network (TGN), is processed, and finally secreted into the circulation. Mutations in provasopressin cause autosomal dominant diabetes insipidus. They prevent native protein folding and cause fibrillar, amyloid-like aggregation in the ER, which eventually results in cell death. Secretory granules of peptide hormones were proposed to constitute functional amyloids and thus might be the cause of amyloid formation of misfolded mutant protein in the ER. Indeed, the same two segments in the precursor-vasopressin and a C-terminal glycopeptide-were found to be responsible for pathological aggregation in the ER and physiological aggregation in granule formation in the TGN. Furthermore, even wild-type provasopressin tends to aggregate in the ER, but is controlled by ER-associated degradation. When essential components thereof, Sel1L or Hrd1, were inactivated, wild-type provasopressin accumulated as fibrillar aggregates in vasopressinergic neurons in mice, causing diabetes insipidus. Evolution of amyloidogenic sequences for granule formation thus made provasopressin dependent on ER quality control mechanisms. These principles may similarly apply to other peptide hormones.

Rare occurrence of central diabetes insipidus with dermatomyositis in a young male

SUMMARY

Central diabetes insipidus (CDI) and several endocrine disorders previously classified as idiopathic are now considered to be of an autoimmune etiology. Dermatomyositis (DM), a rare autoimmune condition characterized by inflammatory myopathy and skin rashes, is also known to affect the gastrointestinal, pulmonary, and rarely the cardiac systems and the joints. The association of CDI and DM is extremely rare. After an extensive literature search and to the best of our knowledge this is the first reported case in literature, we report the case of a 36-year-old male with a history of CDI, who presented to the hospital's endocrine outpatient clinic for evaluation of a 3-week history of progressive facial rash accompanied by weakness and aching of the muscles.

LEARNING POINTS

Accurate biochemical diagnosis should always be followed by etiological investigation. This clinical entity usually constitutes a therapeutic challenge, often requiring a multidisciplinary approach for optimal outcome. Dermatomyositis is an important differential diagnosis in patients presenting with proximal muscle weakness. Associated autoimmune conditions should be considered while evaluating patients with dermatomyositis. Dermatomyositis can relapse at any stage, even following a very long period of remission. Maintenance immunosuppressive therapy should be carefully considered in these patients.

Role of protein aggregation and degradation in autosomal dominant neurohypophyseal diabetes insipidus

This review focuses on the cellular and molecular aspects underlying familial neurohypophyseal diabetes insipidus (DI), a rare disorder that is usually transmitted in an autosomal-dominant fashion. The disease, manifesting in infancy or early childhood and gradually progressing in severity, is caused by fully penetrant heterozygous mutations in the gene encoding prepro-vasopressin-neurophysin II, the precursor of the antidiuretic hormone arginine vasopressin (AVP). Post mortem studies in affected adults have shown cell degeneration in vasopressinergic hypothalamic nuclei. Studies in cells expressing pathogenic mutants and knock-in rodent models have shown that the mutant precursors are folding incompetent and fail to exit the endoplasmic reticulum (ER), as occurs normally with proteins that have entered the regulated secretory pathway. A portion of these mutants is eliminated via ER-associated degradation (ERAD) by proteasomes after retrotranslocation to the cytosol. Another portion forms large disulfide-linked fibrillar aggregates within the ER, in which wild-type precursor is trapped. Aggregation capacity is independently conferred by two domains of the prohormone, namely the AVP moiety and the C-terminal glycopeptide (copeptin). The same domains are also required for packaging into dense-core secretory granules and regulated secretion, suggesting a disturbed balance between the physiological self-aggregation at the trans-Golgi network and avoiding premature aggregate formation at the ER in the disease. The critical role of ERAD in maintaining physiological water balance has been underscored by experiments in mice expressing wild-type AVP but lacking critical components of the ERAD machinery. These animals also develop DI and show amyloid-like aggregates in the ER lumen. Thus, the capacity of the ERAD is exceeded in autosomal dominant DI, which can be viewed as a neurodegenerative disorder associated with the formation of amyloid ER aggregates. While DI symptoms develop prior to detectable cell death in transgenic DI mice, the eventual loss of vasopressinergic neurons is accompanied by autophagy, but the mechanism leading to cell degeneration in autosomal dominant neurohypophyseal DI still remains unknown.

Central Diabetes Insipidus in an Off-pump Coronary Artery Bypass Grafting Surgery

Polyuria in perioperative coronary artery bypass grafting (CABG) surgery is common and mostly benign. Diabetes insipidus (DI) post-CABG is however very rare and mostly have been related with use of cardiopulmonary bypass (CPB) pump. The patient recovered completely with transient requirement of exogenous vasopressin. The central DI may be considered as a differential diagnosis in case of polyuria in the perioperative period of CABG surgery.

How to cite this article

Nasa P, Varma G, Kulkarni A, Chaudhary S, Sagar P. Central Diabetes Insipidus in an Off-pump Coronary Artery Bypass Grafting Surgery. IJCCM 2019;23(11):523-525.

Pituitary Stalk Enlargement in Adults

Pathologies involving the pituitary stalk (PS) are generally revealed by the presence of diabetes insipidus. The availability of MRI provides a major diagnostic contribution by enabling the visualization of the site of the culprit lesion, especially when it is small. However, when only an enlarged PS is found, the etiological workup may be difficult, particularly because the biopsy of the stalk is difficult, harmful and often not contributive. The pathological proof of the etiology thus needs to be obtained indirectly. The aim of this article was to provide an accurate review of the literature about PS enlargement in adults describing the differences between the numerous etiologies involved and consequent different diagnostic approaches. The etiological diagnostic procedure begins with the search for possible other lesions suggestive of histiocytosis, sarcoidosis, tuberculosis or other etiologies elsewhere in the body that could be more easily biopsied. We usually perform neck, thorax, abdomen, and pelvis CT scan; positron emission tomography scan; bone scan; or other imaging methods when we suspect generalized lesions. Measurement of serum markers such as human chorionic gonadotropin, alpha-fetoprotein, angiotensin converting enzyme, and IgG4 may also be helpful. Obviously, in the presence of an underlying carcinoma (particularly breast or bronchopulmonary), one must first consider a metastasis located in the PS. In the case of an isolated PS enlargement, simple monitoring, without histological proof, can be proposed (by repeating MRI at 3-6 months) with the hypothesis of a germinoma (particularly in a teenager or a young adult) that, by increasing in size, necessitates a biopsy. In contrast, a spontaneous diminution of the lesion is suggestive of infundibulo-neurohypophysitis. We prefer not to initiate steroid therapy to monitor the spontaneous course when a watch-and-see attitude is preferred. However, in many cases, the etiological diagnosis remains uncertain, requiring either close monitoring of the lesion or, in exceptional situations, trying to obtain definitive pathological evidence by a biopsy, which, unfortunately, is in most cases performed by the transcranial route. If a simple surveillance is chosen, it has to be very prolonged (annual surveillance). Indeed, progression of histiocytosis or germinoma may be delayed.

Copeptin in the differential diagnosis of hypotonic polyuria

COPEPTIN

Copeptin is secreted in equimolar amount to Arginine Vasopressin (AVP) but can easily be measured with a sandwich immunoassay. Both peptides, copeptin and AVP, show a high correlation. Accordingly, copeptin mirrors the amount of AVP in the circulation and its measurement provides an attractive marker in the differential diagnosis of diabetes insipidus.

THE POLYURIA POLYDIPSIA SYNDROME

Diabetes insipidus-either central or nephrogenic-has to be differentiated from primary polydipsia. Differentiation is crucial since wrong treatment can have deleterious consequences. Since many decades, the "gold standard" for differential diagnosis has been the classical water deprivation test, which has several limitations leading to an overall limited diagnostic accuracy. In addition, the test has a long duration of 17 hours and is cumbersome for patients. Clinical signs and symptoms as well as MRI characteristics overlap between patients with diabetes insipidus and primary polydipsia. Direct measurement of AVP upon osmotic stimulation was first shown to overcome these limitations, but failed to enter clinical practice mainly due to technical limitations of the AVP assay.

COPEPTIN AS DIAGNOSTIC TOOL IN THE POLYURIA POLYDIPSIA SYNDROME

We have recently shown that copeptin, without prior water deprivation, identifies patients with nephrogenic diabetes insipidus. On the other hand, for the more difficult differentiation between central diabetes insipidus and primary polydipsia, a copeptin level of 4.9 pmol/L stimulated with hypertonic saline infusion differentiates between these two entities with a high diagnostic accuracy, and is superior to the water deprivation test. It is important to note that close sodium monitoring during the hypertonic saline test is a prerequisite.

CONCLUSION

Therefore, we propose that copeptin upon hypertonic saline infusion should become the new standard test in the differential diagnosis of diabetes insipidus.

Metastatic Spread to the Pituitary

The pituitary fossa is an uncommon site for metastatic tumor spread. Metastatic lesions to the sellar area derived mostly from breast, lung, renal, prostate, and colon cancers, and rarely from other solid and hematologic malignancies. Almost every cancer has been reported as a source of pituitary metastasis. Pituitary metastasis can involve both the anterior and posterior lobes, but the neuro-hypophysis is mainly involved. Clinical manifestations include diabetes insipidus, hypopituitarism, headache, visual disturbances, ophthalmoplegia, and also compression of adjacent structures by aggressive tumor masses. Metastatic spread to the pituitary from a distant primary malignancy is commonly associated with metastases to other tissues and poor prognosis, unless efficient systemic targeted medical treatment is available for the primary cancer (melanoma, lymphoma).

Diabetes Insipidus: New Concepts for Diagnosis

Diabetes insipidus (DI), be it from central or from nephrogenic origin, has to be differentiated from primary polydipsia. This differentiation is crucial since wrong treatment can have dangerous consequences. For decades, the "gold standard" for differential diagnosis has been the standard water deprivation test. However, this test has several limitations leading to an overall limited diagnostic accuracy. In addition, the test has a long duration of 17 h and is cumbersome for patients. Also clinical signs and symptoms and MRI characteristics overlap between patients with DI and primary polydipsia. Direct measurement of arginine vasopressin (AVP) upon osmotic stimulation was first shown to overcome these limitations, but failed to enter clinical practice mainly due to technical limitations of the AVP assay. Copeptin is secreted in equimolar ratio to AVP, mirroring AVP concentrations in the circulation. We have shown that copeptin, without prior fluid deprivation, identifies patients with nephrogenic DI. For the more difficult differentiation between central DI and primary polydipsia, a copeptin level of 4.9 pmol/L stimulated with hypertonic saline infusion differentiates between these 2 entities with a high diagnostic accuracy and is superior to the water deprivation test. However, it is important to note that close and regular sodium monitoring every 30 min during the hypertonic saline test is a prerequisite, which is not possible in all hospitals. Furthermore, side effects are common. Therefore, a nonosmotic stimulation test would be advantageous. Arginine significantly stimulates copeptin and therefore is a novel, so far unknown stimulus of this peptide. Consequently, infusion of arginine with subsequent copeptin measurement was shown to be an even simpler and better tolerated test, but head to head comparison is still lacking.

Intracranial Germinoma Masquerading as Secondary Granulomatous Hypophysitis: A Case Report and Review of Literature

Germinomas are highly immunogenic tumors eliciting a strong peri-tumoral immune response that can spillover into the surrounding healthy tissues. This phenomenon can also occur in intracranial germinomas, manifesting as secondary hypophysitis. Herein, we report a case of 12-year-old-girl presenting with polyuria and polydispsia. She had central diabetes insipidus (CDI) and panhypopituitarism. Imaging revealed a sellar-suprasellar mass with infundibular stalk thickening. Transphenoidal biopsy revealed epithelioid granulomas with immunostaining negative for germinomatous cells. Other causes of hypophysitis were ruled out. Accordingly, she was diagnosed as primary granulomatous hypophysitis and treated with high-dose corticosteroids. Three years later she again presented with headache, vomiting and diminution of vision. Imaging showed a heterogeneous, solid-cystic peripheral rim-enhancing lesion at the same location with involvement of hypothalamus, ependyma and pineal gland. Cerebrospinal fluid beta-human chorionic gonadotropin was markedly elevated, confirming the diagnosis of an intracranial germ cell tumor. She was started on chemotherapy; however, she succumbed to febrile neutropenia. We performed a literature search and found 18 anecdotal cases of secondary hypophysitis associated with intracranial germinomas. There was a slight male preponderance (male:female 5:4). Two-thirds of the cases were below 18 years of age. Polyuria was the most common presenting manifestation (83%). CDI and panhypopituitarism were seen in 89 and 78% cases, respectively. Imaging evidence of pituitary stalk thickening was seen in 12 cases (67%), while pituitary enlargement and/or sellar mass were reported in 11 cases (61%). Pineal involvement was extremely rare, being reported in only 1 case, implying the predilection of suprasellar (rather than pineal) germinomas in causing secondary hypophysitis. Histologically, 82% had lymphocytic hypophysitis, while 18% had granulomatous hypophysitis. Initially, the diagnosis of germinoma was missed in 60% of the cases who were wrongly treated with corticosteroids. To conclude, physicians should make it a dictum that all children and adolescents presenting with CDI and pituitary stalk thickening should be rigorously screened for an underlying intracranial germinoma before labeling them as primary hypophysitis.

Imaging findings in hypophysitis: a review

Hypophysitis (HP) is a rare acute or chronic inflammatory condition of the pituitary gland. The greatest challenge in the management of HP is establishing a diagnosis through clinical criteria and non-invasive methods and predicting the patients' clinical outcome. The aim of this review is to describe the neuroradiological findings of this rare disease, providing some information regarding the possible differential diagnosis in order to avoid unnecessary surgery. Gadolinium-enhanced pituitary magnetic resonance imaging (MRI) is considered the neuroradiological investigation of choice. The features suggestive for HP include an enlarged triangular- or dumbbell-shaped gland with a thickened and not obviously deviated stalk, further supported by the absence of posterior pituitary bright spot on T1weighted images, particularly in patients presenting with diabetes insipidus. Contrast enhancement pattern is quite variable; dural enhancement has been reported in some cases after intravenous contrast administration. The characterization of the unusual sellar mass is not straightforward and generally results in a wide differential. HP should be primarily differentiated from pituitary adenomas (including pituitary apoplexy), from pituitary metastases, and from other sellar and parasellar tumors, e.g., craniopharyngiomas, germinomas, gliomas, lymphomas, meningiomas, pituicytomas, chordomas, teratomas, dermoids and epidermoids, Rathke's cleft cysts, and abscesses. In patients suspected for secondary forms related to systemic pathology, additional imaging is helpful in identifying other involved sites. Neuroradiologists need to know MRI appearance of this rare disease, as well as its typical symptoms and serological markers. A strict collaboration with endocrinologists and neurosurgeons is mandatory in order to reach a definitive diagnosis, allowing to promptly initiating an appropriate treatment.

Childhood Langerhans cell histiocytosis: a disease with many faces

BACKGROUND

Langerhans cell histiocytosis (LCH) is a group of diseases characterized by the proliferation and accumulation of Langerhans cells. Clinical presentations of LCH vary widely.

DATA SOURCES

A PubMed search was conducted using Clinical Queries with the key term "Langerhans cell histiocytosis". The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. This paper is based on, but not limited to, the search results.

RESULTS

Generally, patients with LCH can be divided into two groups based on the extent of involvement at diagnosis, namely, single-system LCH and multisystem LCH. The involvement may be unifocal or multifocal. Patients with isolated bone lesions typically present between 5 and 15 years of age, whereas those with multisystem LCH tend to present before 5 years of age. The clinical spectrum is broad, ranging from an asymptomatic isolated skin or bone lesion to a life-threatening multisystem condition. Clinical manifestations include, among others, "punched out" lytic bone lesion, seborrheic dermatitis-like eruption, erythematous/reddish-brown crusted/scaly papules/maculopapules/plaques/patches, and eczematous lesions, diabetes insipidus, hepatosplenomegaly, cytopenias, lymphadenopathy, and an acute fulminant disseminated multisystem condition presenting with fever, skin rash, anemia, thrombocytopenia, lymphadenopathy, and hepatosplenomegaly. The diagnosis is clinicopathologic, based on typical clinical findings and histologic/immunohistochemical examination of a biopsy of lesional tissue. Positive CD1a, S100, and/or CD207 (Langerin) immunohistochemical staining of lesional cells is required for a definitive diagnosis. Watchful waiting is recommended for patients with skin-only LCH. Patients with symptomatic or refractory skin-only LCH may be treated with topical tacrolimus/corticosteroids, topical nitrogen mustard, oral methotrexate, or oral hydroxyurea. The current recommended first-line therapy for patients with multisystem LCH is 12 months therapy with prednisone and vinblastine. Mercaptopurine is added for patients with risk organ involvements.

CONCLUSIONS

Because of the broad spectrum of clinical manifestations and the extreme diversity of disease, LCH remains a diagnostic dilemma. Morphological identification of LCH cells and positive immunochemical staining with CD1a, S100, and/or CD207 (Langerin) of lesional cells are necessary for a definitive diagnosis.