Xanthomatous hypophysitis mimicking a pituitary adenoma: case report and review of the literature

Strategy for Identifying a Robust Metabolomic Signature Reveals the Altered Lipid Metabolism in Pituitary Adenoma

Despite the well-established connection between systematic metabolic abnormalities and the pathophysiology of pituitary adenoma (PA), current metabolomic studies have reported an extremely limited number of metabolites associated with PA. Moreover, there was very little consistency in the identified metabolite signatures, resulting in a lack of robust metabolic biomarkers for the diagnosis and treatment of PA. Herein, we performed a global untargeted plasma metabolomic profiling on PA and identified a highly robust metabolomic signature based on a strategy. Specifically, this strategy is unique in (1) integrating repeated random sampling and a consensus evaluation-based feature selection algorithm and (2) evaluating the consistency of metabolomic signatures among different sample groups. This strategy demonstrated superior robustness and stronger discriminative ability compared with that of other feature selection methods including Student's t-test, partial least-squares-discriminant analysis, support vector machine recursive feature elimination, and random forest recursive feature elimination. More importantly, a highly robust metabolomic signature comprising 45 PA-specific differential metabolites was identified. Moreover, metabolite set enrichment analysis of these potential metabolic biomarkers revealed altered lipid metabolism in PA. In conclusion, our findings contribute to a better understanding of the metabolic changes in PA and may have implications for the development of diagnostic and therapeutic approaches targeting lipid metabolism in PA. We believe that the proposed strategy serves as a valuable tool for screening robust, discriminating metabolic features in the field of metabolomics.

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.

Xanthogranulomatous hypophysitis: A rare presentation in a young female patient

Hypophysitis is a rare inflammatory condition that may present both clinically and radiologically as a neoplastic lesion. Xanthogranulomas are rare intracranial lesions with controversial etiology. Here, we report a clinical case of histologically confirmed xanthogranulomatosis hypophysitis in a young female with type I diabetes mellitus and hypothyroidism.

Hypopituitarism is an important cause of persistent hypoglycemia in a patient with previously well‐controlled diabetes. The combination of autoimmunity, hypopituitarism, and a sellar mass may represent autoimmune hypophysitis, which can mimic a pituitary adenoma. Several histological subtypes of hypophysitis have been found, and XH is a rare subtype.

Xanthomatous Hypophysitis Secondary to a Ruptured Rathke's Cleft Cyst: A Case Report

Hypophysitis (HP) is a rare disease which develops secondary to chronic or acute inflammation of the pituitary gland and may cause symptoms related to pituitary dysfunction and mass compression. Lymphocytic HP is the most common subtype of primary HP, while xanthomatous HP (XHP) is considered the rarest form, with 35 reported cases, to date. A 35-year-old woman was initially admitted to a Gynecology clinic with a 2-year history of amenorrhea and headache. She was started on cabergoline 0.5 mg twice a week for macroprolactinoma. Due to persistent amenorrhea with low gonadotropins, she was referred to our Endocrinology clinic. Her pituitary function profile revealed panhypopituitarism and a 13×11×12 mm sized sellar mass with diffuse enhancement which sustained toward the infundibulum and dura was observed on the gadolinium-enhanced pituitary MRI. The patient underwent an endoscopic endonasal transsphenoidal approach for tumor resection and thick yellowish fluid draining from the lesion was observed. The histopathological diagnosis was reported as a rupture of an Rathke’s cleft cyst and an XHP. The surgery did not improve the symptoms/pituitary functions, however, headache recovered immediately after the first dose of high dose methylprednisolone treatment. The inflammatory process in a xanthomatous lesion may actually be a secondary response to mucous fluid content release from a ruptured cyst, thus recommended to classify XHP as secondary hypophysitis. Since the differentiation of XHP from other pituitary tumors may be challenging preoperatively, surgery is the major diagnostic tool and also, the most recommended therapeutic option.

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.

Xanthomatous Hypophysitis Presenting in an Adolescent Girl: A Long-Term Follow-Up of a Rare Case and Review of the Literature

Objective

Primary hypophysitis refers to the isolated inflammation of the pituitary gland not associated with other secondary causes. Among its histopathologic subtypes, xanthomatous is the rarest.

Methods

We describe a 22-year-old woman with xanthomatous hypophysitis (XH), its clinical progression over 8 years as well as the treatment effects of prednisolone and azathioprine. Our patient was first referred for severe short stature and delayed puberty at the age of 14 years.

Results

Investigations revealed multiple pituitary deficiencies. Magnetic resonance imaging showed a pituitary mass whereby a partial resection was performed. A full resection was not feasible due to the location of the mass. The histopathologic analysis of the tissue was consistent with XH. The results of secondary workout for neoplasm, infection, autoimmune, and inflammatory disorders were negative. After surgery, a progressive enlargement of the mass was observed. Two courses of prednisolone were administered with a significant reduction in the mass size. Azathioprine was added due to the unsustained effects of prednisolone when tapered off and the concern of steroid toxicity with continued use. No further increase in the mass size was noted after 6 months on azathioprine.

Conclusion

Glucocorticoid and immunotherapy are treatment options for XH; however, more cases are needed to better understand its pathogenesis and clinical progression.

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 (Including IgG4 and Immunotherapy)

Hypophysitis is characterized by inflammation of the pituitary gland that can be primary (PH) or secondary (SH) to other diseases or following drug administration. It may also be classified according to anatomical and histopathological criteria, leading to variable degrees of hypopituitarism and/or compressive symptoms to nearby structures. There has recently been an increase in the number of hypophysitis cases, raising the interest on the spectrum of its pathogenesis, clinical, biochemical/endocrinological, and imaging features. However, the use of conventional biomarkers, including currently utilized pituitary autoantibodies, has relatively limited diagnostic accuracy. Lymphocytic hypophysitis (LH) is the commonest cause of PH, whereas IgG4-related hypophysitis is increasingly being recognized. Histiocytosis and granulomatous diseases are the most frequent causes of SH, although infections and lymphoma have also been reported. The increasing use of immune checkpoint inhibitors in oncology is associated with a high incidence of hypophysitis, providing further understanding of its pathogenesis. Hypophysitis can occur silently and be easily missed, potentially leading to substantial morbidity or mortality due to adrenal insufficiency, requiring a high index of clinical suspicion and timely initiation of appropriate treatment. In most cases of LH or drug-induced hypophysitis, active surveillance along with replacement of established hormonal deficiencies is needed. In the presence of compressive and/or evolving symptoms, treatment with glucocorticoids either alone or in combination with other immunosuppressive agents can be used. Surgical decompression is reserved for nonresponsive cases with threatened vital structures. Timely diagnosis and intervention are important to minimize disease-related morbidity and mortality. We aimed to review current concepts and recent developments in the pathogenesis, diagnosis, and management of 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.

Xanthomatous hypophysitis causing hypogonadotropic hypogonadism resulting in delayed presentation of slipped capital femoral epiphysis

An 18-year-old man who underwent bilateral pinning of his hip joints after a left unstable Slipped Capital Femoral Epiphysis (right pinned prophylactically) was noted to have delayed secondary sexual characteristics and post-operative diabetes insipidus. The patient also described a history of fatigue, headache and polydipsia for the past 4 years. Endocrine investigations revealed reduced androgen levels, hypocortisolism, a borderline normal Serum ACE and secondary hypothyroidism. Magnetic Resonance Imaging of the pituitary gland identified an enhancing mass and a thickened stalk which trans-nasal endoscopic biopsy found to be necrotic with pus. Histology confirmed a diagnosis of Xanthomatous Hypophysitis, an inflammatory condition likely related to a partial rupture of a Rathke cleft cyst. The patient was subsequently commenced on Androgen, Thyroxine, Desmopressin and Hydrocortisone therapy with on-going endocrine follow-up. Although endocrine dysfunction & hypogonadism has been recognised to be a risk factor for SCFE at an atypically older age, due to reduced androgen levels leading to a weakened physeal plate, this is the first known case of a Xanthomatous Hypophysitis resulting in pituitary dysfunction and eventual SCFE. This case highlights that an increased range of pituitary disorders should be considered in late presentations of SCFE; and vice versa the risk of SCFE should be considered in patients with prolonged hypogonadotropic hypogonadism.

Accuracy of Frozen Section with Histopathological Report in an Institute

INTRODUCTION

Frozen section helps in rapid intra-operative diagnosis. It is commonly used during surgical procedures to detect malignancy so that modifications of surgery can be decided at the time of surgery on the table. Frozen section is also performed for evaluation of surgical margins and detection of lymph node metastasis. In addition it is applied for detection of unknown pathological processes.The objective of this study was to assess the accuracy of frozen section diagnosis in comparison to gold standard histopathological diagnosis and to find concordance and discordance rate of frozen section with histopathological report.

METHODS

This was a cross sectional study of 41 frozen section samples done in the department of pathology of BP Koirala Institute of Health Sciences from September 2014 to August 2015. All frozen section samples with their permanent tissue samples sent for final histopathological evaluation were included in the study.

RESULTS

The overall accuracy of frozen section diagnosis was 97%. The sensitivity was 94%, specificity was 87%, positive predictive value was 90% and negative predictive value was 93%. The concordance rate was 90.2% and the discordance rate was 9.8%.

CONCLUSIONS

The results of frozen section varied in different organ systems and the common cause of discrepancy in our study were the gross sampling error and the interpretational error.

Review of xanthomatous lesions of the sella

Xanthomatous lesions of the sellar region have traditionally been divided into two separate categories, xanthomatous hypophysitis (XH) and xanthogranuloma (XG) of the sellar region. The seminal article on XH, a condition typified by foamy histiocytes and lymphoplasmacytic infiltrates in the pituitary gland/sellar region, but usually little or no hemosiderin pigment, detailed three patients. However, most reports since that time have been single cases, making understanding of the entity difficult. In contrast, the seminal report on XG, characterized by sellar region cholesterol clefts, lymphoplasmacytic infiltrates, marked hemosiderin deposits, fibrosis, multinucleated giant cells around cholesterol clefts, eosinophilic granular necrotic debris, and accumulation of macrophages, included 37 patients, allowing more insights into etiology. Few examples could be linked to adamantinomatous craniopharyngioma, and although ciliated epithelium similar to that of Rathke cleft cyst (RCC) was identified up to 35% of the 37 cases, it could not be proven that XG was related to hemorrhage into RCC. Case reports since that time, however, occasionally linked XG to RCC when an etiology could be identified at all, and a few recognized that a spectrum exists in xanthomatous lesions of the sella. They review literature, adding 23 cases from our own experience, to confirm that overlap occurs between XH and XG, and that the majority-but not all-can be linked to RCC leakage/rupture/hemorrhage. It was suggested that progressive accumulation of hemosiderin pigment in the lesion, possibly caused by the multiple episodes of bleeding, could account for the transition of at least some cases of XH to XG.

Xanthomatous Hypophysitis Is Associated with Ruptured Rathke's Cleft Cyst

Xanthomatous hypophysitis is a rare inflammatory disease of the pituitary gland that can mimic a neoplastic lesion clinically and radiologically. Its pathogenesis remains largely unknown, although recent evidence suggests that pituitary inflammation may occur as a secondary reaction to mucous content released from a ruptured cyst. In a series of 1221 pituitary specimens, we identified seven cases of xanthomatous hypophysitis. Six patients had complete radiological and biochemical workup preoperatively: a cystic-appearing pituitary mass was identified in all six patients (100%) with a mean size of 2.0 cm (range 1.4-2.5 cm) on imaging, and pituitary endocrine dysfunction was noted in five patients (83.3%). In all cases, the pituitary mass was resected through an endoscopic transsphenoidal approach. Pathological examination revealed the presence of foamy macrophages admixed with variable amounts of giant cells and chronic inflammatory cells, confirming the diagnosis of xanthomatous hypophysitis. Additionally, all cases presented with concurrent findings of ruptured Rathke's cleft cyst, with the exception of one patient who had previous surgery for a Rathke's cleft cyst, followed by recurrence and diagnosis of xanthomatous hypophysitis. While accurate distinction of hypophysitis from a pituitary neoplasm can be problematic in the preoperative setting, the identification of a cystic lesion in the sella turcica should raise the possibility of such an entity in the clinical and radiological differential diagnosis. The current series provides further evidence that xanthomatous hypophysitis predominantly occurs as a secondary reaction to a ruptured Rathke's cleft cyst; thus, it is best classified as a secondary (reactive) hypophysitis.

Xanthomatous hypophysitis associated with autoimmune disease in an elderly patient: A rare case report

Background:

Xanthomatous hypophysitis (XH) is an extremely rare form of primary hypophysitis characterized by infiltration of the pituitary gland by mixed types of inflammatory cells, including foamy cells, plasma cells, and small mature lymphocytes. XH manifests as varying degrees of hypopituitarism. Although several previous reports have denied a possible contribution of autoimmune mechanism, the exact pathogenesis of XH remains unclear.

Case Description:

We describe the case of a 72-year-old woman with a history of rheumatoid arthritis and Sjögren's syndrome who presented with panhypopituitarism and diabetes insipidus. At the time of her visit, she also experienced relapsed rheumatoid arthritis and Sjögren's syndrome, manifesting as arthralgia. Magnetic resonance imaging (MRI) showed a multicystic mass in the sellar and suprasellar regions. In the course of steroid replacement therapy for hypocortisolism, the patient's arthralgia diminished, and MRI revealed shrinkage of the mass. XH was diagnosed histologically following a transsphenoidal endoscopic biopsy, and it was the oldest case of XH.

Conclusion:

To the best of our knowledge, this patient is the oldest of reported patients diagnosed with XH. Steroid therapy may be effective to XH temporarily. XH should be considered when diagnosing pituitary cystic lesions in elderly patients with autoimmune disease.

Xanthomatous hypophysitis

We present a 69-year-old woman who presented with chronic headaches and was found to have a pituitary mass on MRI, which was biopsied and said to be lymphocytic hypophysitis. The woman was placed on prednisone and followed with routine eye examinations. Two years later, the lesion gradually increased in size and the woman developed a decrease in peripheral vision in the right eye. An MRI showed abutment of the right optic nerve by the mass. A repeat endoscopic transsphenoidal biopsy/resection of the pituitary lesion was performed. Histopathological analysis of the specimen was consistent with diagnosis of xanthomatous hypophysitis (XH). XH is an inflammatory disorder of the pituitary gland characterized by an infiltration of lipid-laden histiocytes, also known as xanthoma cells. The mass was biopsied and a diagnosis of lymphocytic hypophysitis was made. The woman reported improved visual acuity and peripheral vision postoperatively. One year after the second resection, her visual symptoms worsened. Repeat MRI revealed expansion of the residual pituitary tissue. She was referred to the radiation oncology department for external beam radiation therapy and was placed on a maintenance dose of steroids. Since undergoing radiation therapy, her vision has improved slightly and her 3month MRI revealed stable lesion size. This woman illustrates a rare pituitary pathology presented with a literature review of published patients describing xanthomatous hypophysitis. A discussion of the clinical presentation, epidemiology, etiology, diagnosis, histology and treatment is provided.

Xanthogranulomatous hypophysitis: a rare and often mistaken pituitary lesion

Xanthogranulomatous hypophysitis (XGH) is a very rare form of pituitary hypophysitis that may present both clinically and radiologically as a neoplastic lesion. It may either be primary with an autoimmune aetiology and can occur in isolation or as a part of autoimmune systemic disease or secondary as a reactive degenerative response to an epithelial lesion (e.g. craniopharyngioma (CP), Rathke's cleft cyst, germinoma and pituitary adenomas) or as a part of a multiorgan systemic involvement such as tuberculosis, sarcoidosis or granulomatosis. It may also present with a variation of symptoms in children and adults. Our case series compares the paediatric and adult presentations of XGH and the differential diagnoses considered in one child and two adult patients, highlighting the wide spectrum of this condition. Endocrine investigations suggested panhypopituitarism in all three patients and imaging revealed a suprasellar mass compressing the optic chiasm suggestive of CP or Rathke's cleft cyst in one patient and non-functioning pituitary macroadenoma in two patients. Magnetic resonance imaging (MRI) demonstrated mixed signal intensities on T1- and T2-weighted sequences. Following endoscopic transsphenoidal surgery, histological analysis revealed necrotic material with a xanthogranulomatous reaction confirming XGH in two patients and a necrobiotic granulomatous chronic inflammatory infiltrate with neutrophils in one patient, which is not typical of current descriptions of this disorder. This case series describes the wide spectrum of XGH disease that is yet to be defined. Mixed signal intensities on T1- and T2-weighted MRI sequences may indicate XGH and diagnosis is confirmed by histology. Histological variation may indicate an underlying systemic process.

LEARNING POINTS

XGH is a rare form of pituitary hypophysitis with a wide clinical and histological spectrum and can mimic a neoplastic lesion.XGH primarily presents with growth arrest in children and pubertal arrest in adolescents. In adults, the presentation may vary.A combination of hypopituitarism and mixed signal intensity lesion on MRI is suggestive of XGH and should be considered in the differential diagnosis of sellar lesions.Radical surgery is the treatment of choice and carries an excellent prognosis with no recurrence.

Update on hypophysitis and TTF-1 expressing sellar region masses

This article reviews recent literature on sellar region masses that most closely mimic nonsecretory pituitary adenomas: hypophysitis, pituicytoma, spindle cell oncocytoma, and granular cell tumor of neurohypophysis. Even today, these four entities often cannot be confidently distinguished from each other clinically or by preoperative neuroimaging features. Thus, they often come to biopsy/surgical resection and require tissue confirmation of diagnosis. Causes of secondary and primary hypophysitis will be discussed, including two newly described types, IgG4 plasma cell hypophysitis and hypophysitis caused by anti-cytotoxic T-lymphocyte antigen 4 antibody therapy for cancer. For the neoplastic conditions, emphasis will be placed on literature that has emerged since these entities were first codified in the 2007 World Health Organization fascicle. The finding that immunohistochemical staining for thyroid transcription factor-1 is shared by pituicytoma, spindle cell oncocytoma, and granular cell tumor of neurohypophysis suggests common lineage and explains why histological overlap can be encountered. We incorporate our own experiences over the last 30 years from two referral institutions with specialty practices in pituitary region masses.

Steroid responsive xanthomatous hypophysitis associated with autoimmune thyroiditis: a case report

We report the case of a 36-year-old woman who presented with headache, fever, and amenorrhea. Laboratory analysis revealed hypopituitarism and autoimmune thyroiditis, while a cerebrospinal fluid study suggested concurrent aseptic meningitis. A magnetic resonance image (MRI) scan revealed a 1.0×0.9 cm cystic mass enlarging the sella turcica. Surgical resection via an endoscopic transsphenoidal route was performed. The histological finding of the excised tissue revealed foamy histiocytes with vacuolated cytoplasm, supporting the diagnosis of xanthomatous hypophysitis. Although a residual soft lesion was observed on the MRI image postoperatively, the patient's headache and fever improved. Ten months after surgery, the patient complained of visual impairment and headache, and the residual mass had enlarged into the suprasellar area. High dose (500 mg intravenous) methylprednisolone was administered for 3 days. During the methylprednisolone pulse therapy, the patient's visual acuity and headache improved. A follow-up MRI taken after methylprednisolone therapy showed a marked mass reduction. Our case supports an autoimmune pathophysiology for xanthomatous hypophysitis and suggests that high dose glucocorticoid therapy as a treatment option.

Growth hormone and proopiomelanocortin are targeted by autoantibodies in a patient with biopsy-proven IgG4-related hypophysitis

Hypophysitis is a chronic inflammation of the pituitary gland often caused by autoimmunity. Among the autoimmune diseases it is one of the few where the autoantigens remain to be identified. The goal of the paper was to characterize the antigenic profile in a previously reported patient with IgG4-related hypophysitis. Immunofluorescence and immunoblotting were performed to detect antibodies to human pituitary proteins. The proteins recognized by western blotting were then submitted to mass spectrometry for sequencing. The patient's autoantibodies recognized two unique bands around 40 and 30 kDa on immunoblotting. Sequencing revealed one peptide from proopiomelanocortin in the 40 kDa band and four peptides from growth hormone in the 30 kDa band. This work represents the first antigenic profile in IgG4-related hypophysitis, and the first recognition of proopiomelanocortin as a possible pituitary autoantigen. In addition, the work supports previous suggestions of growth hormone as a pituitary autoantigen. Further studies are needed to prove the pathogenicity and diagnostic utility of these two pituitary proteins.

Xanthomatous hypophysitis

Xanthomatous hypophysitis (XH) is the rarely seen primary form of hypophysitis. The histological differential diagnosis includes other causes of hypophysitis, Erdheim-Chester disease (ECD), Langerhans cell histiocytosis, Rosai-Dorfman disease and plasma cell granulomas. We present a 39-year-old woman admitted to our department with headache, menstrual irregularity and galactorrhea. The MRI revealed a lesion with a central cystic/necrotic region and a diameter of almost 1cm. Histologic examination showed an inflammatory infiltrate of numerous foamy histiocytes, surrounding the necrotic tissue. On immunohistochemical sections, infiltrating foamy cells stained strongly positive for CD68, and negative for CD1a and S100. After establishing the diagnosis of XH, the patient underwent glucocorticoid treatment. XH should be considered in the differential diagnosis of pituitary lesions. Since XH is rare, it is difficult to assess the efficacy of medical/surgical treatment of this entity accurately.

From pituitary expansion to empty sella: disease progression in a mouse model of autoimmune hypophysitis

Lymphocytic hypophysitis has a variable clinical course, where a swelling of the pituitary gland at presentation is thought to be followed by pituitary atrophy and empty sella. Data in patients, however, are scanty and contradictory. To better define the course of hypophysitis, we used an experimental model based on the injection of pituitary proteins into SJL mice. A cohort of 33 mice was divided into three groups: 18 cases were immunized with pituitary proteins emulsified in complete Freund's adjuvant; six controls were injected with adjuvant only; and nine controls were left untreated. Mice were followed by cranial magnetic resonance imaging (MRI) for up to 300 d, for a total of 106 MRI scans, and killed at different time points to correlate radiological and pathological findings. Empty sella was defined as a reduction in pituitary volume greater than 2 sd below the mean volume. All immunized mice showed by MRI a significant expansion of pituitary volume during the early phases of the disease. The volume then decreased gradually in the majority of cases (14 of 18, 78%), reaching empty sella values by d 300 after immunization. In a minority of cases (four of 18, 22%), the decrease was so rapid and marked to induce a central area of necrosis accompanied by hemorrhages, mimicking the condition known in patients as pituitary apoplexy. No radiological or pathological changes were observed in controls. Overall, these findings indicate that the evolution of hypophysitis is complex but can lead, through different routes, to the development of empty sella.