Re-analysis of gene mutations found in pituitary stalk interruption syndrome and a new hypothesis on the etiology.

Background: Pituitary stalk interruption syndrome (PSIS) is a complex clinical syndrome characterized by varied pituitary hormone deficiencies, leading to severe manifestations across multiple systems. These include lifelong infertility, short stature, mental retardation, and potentially life-threatening pituitary crises if not promptly diagnosed and treated. Despite extensive research, the precise pathogenesis of PSIS remains unclear. Currently, there are two proposed theories regarding the pathogenic mechanisms: the genetic defect theory and the perinatal injury theory. Methods: We systematically searched English databases (PubMed, Web of Science, Embase) and Chinese databases (CNKI, WanFang Med Online, Sinomed) up to February 24, 2023, to summarize studies on gene sequencing in PSIS patients. Enrichment analyses of reported mutated genes were subsequently performed using the Metascape platform. Results: Our study included 37 articles. KEGG enrichment analysis revealed mutated genes were enriched in the Notch signaling pathway, Wnt signaling pathway, and Hedgehog signaling pathway. GO enrichment analysis demonstrated mutated genes were enriched in biological processes such as embryonic development, brain development, axon development and guidance, and development of other organs. Conclusion: Based on our summary and analyses, we propose a new hypothesis: disruptions in normal embryonic development, partially stemming from the genetic background and/or specific gene mutations in individuals, may increase the likelihood of abnormal fetal deliveries, where different degrees of traction during delivery may lead to different levels of pituitary stalk interruption and posterior lobe ectopia. The clinical diversity observed in PSIS patients may result from a combination of genetic background, specific mutations, and variable degrees of traction during delivery.

Isolated hypogonadotropic hypogonadism in adolescence: Do we need to measure the pituitary, stalk or other imaging markers? A retrospective magnetic resonance imaging study.

BACKGROUND: Rapid changes in the size of the pituitary gland occur during the pubertal period. Therefore, measuring and reporting magnetic resonance imaging (MRI) in adolescents with pituitary disorders can cause unease among radiologists. Our aim was to compare the size of the pituitary gland, stalk and other previously described imaging tools in patients with isolated hypogonadotropic hypogonadism (HH) versus adolescents with a normal pituitary gland. METHODS: Forty-one patients (22 female, 19 male, mean age 16.3 ±2.0 years) with HH who underwent MRI prior to starting hormone treatment were enrolled. Age, sex, and genetic mutations were noted. Pituitary height, width on the coronal plane, anteroposterior (AP) diameter on the sagittal plane, stalk thickness, pons ratio (PR), clivus canal angle (CCA) and Klaus index (KI) were measured by two radiologists twice with a one-month interval blinded to each other and patient information. Measurements were compared with the control group, including 83 subjects with normal hypothalamic-pituitary-gonadal axis and normal pituitary gland on MRI. Inter-rater and intra-rater agreements were also evaluated. RESULTS: No significant differences were found between the two groups regarding height, width or AP diameter (p = 0.437, 0.836, 0.681 respectively). No significant differences were found between the two groups regarding CCA and PR (p = 0.890, 0.412 respectively). The KI of the male patients was significantly higher than that of the female patients and the control group (p < 0.001). The interrater agreement was moderate for pituitary height and width, poor for pituitary AP diameter and stalk thickness, good for PR and KI, and excellent for CCA. CONCLUSIONS: The measurements of the pituitary gland, stalk and posterior fossa structures were similar in adolescents with or without isolated HH. Consequently, pituitary gland, stalk or other posterior fossa measurements are unnecessary when evaluating a normal appearing pituitary gland on MRI.

Pituitary tuberculoma with panhypopituitarism masquerading as a pituitary adenoma.

Tuberculosis of the hypothalamo-pituitary axis is extremely uncommon. The presentation of panhypopituitarism in a case of sellar tuberculosis is an even rarer occurrence. We present a case of a 44-year-old man who presented with complaints of headache and right-sided diminution of vision for six months. A hormone profile showed abnormal anterior pituitary assay suggestive of panhypopituitarism. Magnetic Resonance imaging of the brain showed a sellar mass measuring 1.8 × 1.5 × 1.3 cm with suprasellar extension suggestive of a pituitary adenoma. Histopathological examination showed multiple epithelioid cell granulomas along with Langhans giant cells and mixed inflammatory infiltrates against a necrotic background. Zeihl Neelson stain demonstrated the presence of acid-fast bacilli. Thus, a final diagnosis of pituitary tuberculoma was made, and the patient started on antitubercular therapy. It is extremely important to correctly diagnose sellar tuberculosis as the treatment is entirely different, and the patient usually responds well to therapy.

The Significance of the Intercarotid Distances for Transsphenoidal Pituitary Surgery: A Magnetic Resonance Imaging Study.

OBJECTIVE: We performed magnetic resonance imaging (MRI) to analyze the distance between the left and right internal carotid arteries (ICD) around pituitary tumors for transsphenoidal surgery (TSS). METHODS: Measurements were performed using thin slice T2-weighted MRI, and/or time-of-flight (TOI) MR angiography imaging for 64 nonfunctioning pituitary neuroendocrine tumors (NF-pitNETs), 22 growth hormone-producing pitNETs (GH producing pitNETs), and 46 normal controls. We measured the ICD at 3 anatomic levels: at the distal dural ring (ICD-A); at the most concave point of the C4-C5 bend (ICD-B); and at the most convex point of the C4 bend (ICD-C). Additionally, we measured the sagittal distance between the tuberculum selle and the junction of the sellar floor and clivus on the midsagittal MRI (TS-C). RESULTS: We found that ICD-B was the longest and that ICD-A was the shortest among the 3 distance parameters in all groups (P < 0.001). The comparison of the groups revealed that the NF-pitNET group had longer distances than the normal control group at all ICDs (P < 0.001). The GH producing pitNET group had longer distance than the normal control group at ICD-B (P < 0.001). Tumor volume was correlated with ICD-A and ICD-B in the NF-pitNET, and was correlated with ICD-C in the GH producing pitNET group. CONCLUSIONS: Among the distance parameters, ICD-B is the longest, and was approximately twice the width of the TS-C. The shape of the sella is an ellipse that is widest in the lateral dimension in TSS. A horizontal based dural incision may be more rational than a conventional X-shaped dural incision.

[Transient thickening of the pituitary stalk followed by a supra-pituitary Langerhansian histiocytosis : consequence or mere coincidence ?] / Cas clinique. Épaississement transitoire de la tige pituitaire suivi d'une histiocytose langerhansienne supra-hypophysaire : conséquence ou simple coïncidence ?

One of the difficult challenges in endocrinology is the etiological diagnosis of isolated thickened pituitary stalk (PS). We report the case of a woman in whom a thickened PS was diagnosed following the onset of central diabetes insipidus revealed by polyuria-polydypsia syndrome of late pregnancy and postpartum. The pituitary exploration showed panhypopituitarism with disconnecting hyperprolactinemia. An etiological investigation for an inflammatory, granulomatous or tumour cause was carried out, but was negative. Postpartum lymphocytic hypophysitis was then retained. However, the course was puzzling with a control pituitary MRI showing disappearance of the PS thickening with paradoxical appearance of a supra-pituitary tumour, the biopsy of which concluded of being a Langerhansian histiocytosis. This paradoxical sequence is unusual and has not been reported before. It called into question the autoimmune lymphocytic origin of the thickened PS, initially considered, and raised the likelihood of a causal relationship between this PS thickening and Langerhansian histiocytosis.

Le diagnostic étiologique d'un épaississement isolé de la tige pituitaire (TP) constitue l'un des grands défis en endocrinologie. Nous rapportons le cas d'une patiente chez qui un épaississement de la TP a été diagnostiqué suite à la survenue d'un diabète insipide central révélé par un syndrome polyuro-polydypsique de fin de grossesse et du post-partum. Le bilan hypophysaire a montré un panhypopituitarisme avec une hyperprolactinémie de déconnexion. Une enquête étiologique à la recherche d'une cause inflammatoire, granulomateuse ou tumorale a été menée et s'est avérée négative. Une hypophysite lymphocytaire du post-partum a alors été retenue. Cependant, l'évolution a été déroutante avec, à l'IRM hypophysaire de contrôle, la disparition de l'épaississement de la TP et l'apparition paradoxale d'une tumeur suprahypophysaire dont la biopsie a conclu à une histiocytose langerhansienne. Cette évolution paradoxale est inhabituelle et n'a pas été rapportée auparavant. Elle a remis en question l'origine lymphocytaire auto-immune de l'épaississement de la TP, retenue initialement, et a soulevé la possibilité d'une relation de cause à effet entre cet épaississement de la TP et l'histiocytose langerhansienne.

A procedure in mice to obtain intact pituitary-infundibulum-hypothalamus preparations: a method to evaluate the reconstruction of hypothalamohypophyseal system.

PURPOSE: The histopathological study of brain tissue is a common method in neuroscience. However, efficient procedures to preserve the intact hypothalamic-pituitary brain specimens are not available in mice for histopathological study. METHOD: We describe a detailed procedure for obtaining mouse brain with pituitary-hypothalamus continuity. Unlike the traditional methods, we collect the brain via a ventral approach. We cut the intraoccipital synchondrosis, transection the endocranium of pituitary, broke the spheno-occipital synchondrosis, expose the posterior edge of pituitary, separate the trigeminal nerve, then the intact pituitary gland was preserved. RESULT: We report an more effective and practical method to obtain continuous hypothalamus -pituitary preparations based on the preserve of leptomeninges. COMPARED WITH THE EXISTING METHODS: Our procedure effectively protects the integrity of the fragile infundibulum preventing the pituitary from separating from the hypothalamus. This procedure is more convenient and efficient. CONCLUSION: We present a convenient and practical procedure to obtain intact hypothalamic-pituitary brain specimens for subsequent histopathological evaluation in mice.

A case of pituitary gland abscess associated with granulomatous hypophysitis.

BACKGROUND: Granulomatous hypophysitis is a rare disease that presents with chronic inflammation of the pituitary gland. In this study, we reported a case of granulomatous hypophysitis associated with a pituitary abscess. CASE PRESENTATION: A 39-year-old woman presented with a 2-year history of infertility. For the past six months, she has suffered from amenorrhea, decreased libido, headaches, and vertigo. She was referred to our hospital with a suspected diagnosis of nonfunctioning pituitary adenoma based on her presentation and brain MRI findings. She underwent trans-sphenoidal surgery (TSS). Direct observation during surgery revealed drainage of malodor pus and pituitary gland abscess. The histopathological evaluation also showed granulomatous hypophysitis and neutrophilic microabscess formation. The patient was initially treated with high doses of ceftriaxone (2 g twice daily) and metronidazole (500 mg (mg) four times per day). Also, the patient received cortisol replacement therapy after the operation. After obtaining the antibiogram and culture results, the treatment regimen was continued for 4 weeks postoperatively, followed by amoxicillin-clavulanate (500/125 mg three times daily) for a total duration of 12 weeks. CONCLUSION: The patient recovered uneventfully and the postoperative MRI was normal without any remnant lesions.

The evolution of pituitary cysts in growth hormone-treated children.

OBJECTIVES: We have previously shown that pituitary cysts may affect growth hormone secretion. This study sought to determine cyst evolution during growth hormone treatment in children. METHODS: Forty-nine patients with short stature, a pituitary cyst, and at least two brain MRI scans were included. The percent of the pituitary gland occupied by the cyst (POGO) was calculated, and a cyst with a POGO of ≤15% was considered small, while a POGO >15% was considered large. RESULTS: Thirty-five cysts were small, and 14 were large. Five of the 35 small cysts grew into large cysts, while 6 of the 14 large cysts shrunk into small cysts. Of 4 cysts that fluctuated between large and small, 3 presented as large and 1 as small. Small cysts experienced greater change in cyst volume (CV) (mean=61.5%) than large cysts (mean=-0.4%). However, large cysts had a greater net change in CV (mean=44.2 mm3) than small cysts (mean=21.0 mm3). Older patients had significantly larger mean pituitary volume than younger patients (435.4 mm3 vs. 317.9 mm3) and significantly larger mean CV than younger patients (77.4 mm3 vs. 45.2 mm3), but there was no significant difference in POGO between groups. CONCLUSIONS: Pituitary cyst size can vary greatly over time. Determination of POGO over time is a useful marker for determining the possibility of a pathologic effect on pituitary function since it factors both cyst and gland volume. Large cysts should be monitored closely, given their extreme, erratic behavior.

Delayed Diagnosis of Congenital Combined Pituitary Hormone Deficiency including Severe Growth Hormone Deficiency in Children with Persistent Neonatal Hypoglycemia-Case Reports and Review.

Apart from stimulation of human growth and cell proliferation, growth hormone (GH) has pleiotropic metabolic effects in all periods of life. Severe GH deficiency is a common component of combined pituitary hormone deficiency (CPHD). CPHD may be caused by mutations in the genes encoding transcription factors and signaling molecules involved in normal pituitary development; however, often its genetic cause remains unknown. Symptoms depend on which hormone is deficient. The first symptom of GH or adrenocorticotropic hormone (ACTH) deficiency may be persistent hypoglycemia in apparently healthy newborns, which is often neglected. Diagnosing CPHD is based on decreased concentrations of hormones secreted by the anterior pituitary and peripheral endocrine glands. Findings in magnetic resonance imaging vary widely, including anterior pituitary hypoplasia/aplasia or pituitary stalk interruption syndrome (PSIS). Delayed diagnosis and treatment can be life-threatening. GH therapy is necessary to recover hypoglycemia and to improve auxological and psychomotor development. We present two girls, diagnosed and treated in our departments, in whom the diagnosis of CPHD was delayed, despite persistent neonatal hypoglycemia; and a review of similar cases, with attention paid to progress in the genetic assessments of such patients, since the introduction of whole exome sequencing that is especially important for PSIS.

Normal or elevated prolactin is a good indicator to show pituitary stalk interruption syndrome in patients with multiple pituitary hormone deficiency.

OBJECTIVES: To determine the importance of serum prolactin (PRL) in the detection of pituitary stalk interruption syndrome (PSIS) in children with multiple pituitary hormone deficiency (MPHD). We hypothesized that PRL elevation might be a diagnostic indicator of pituitary stalk pathologies. METHODS: Clinical, radiological, and laboratory features of the 50 cases of MPHD were studied. RESULTS: The median age at presentation of the 50 cases (52%, n=26 were female) was 6.61 (0.02-18.9) years. PSIS was detected in 60% (n=30), pituitary hypoplasia in 32% (n=16), partial empty sella in 6% (n=3), and only 2% (n=1) was reported as normal. Out of 50 patients, 21.3% (n=10) were hypoprolactinemic, 44.7% (n=19) were normoprolactinemic, and 34% (n=16) were hyperprolactinemic. The median PRL value was 27.85 (4.21-130) ng/mL in patients with PSIS and 5.57 (0-41.8) ng/mL in patients without PSIS. Additional hormone deficiencies, especially ACTH and LH were detected in follow-up. CONCLUSIONS: Patients with normal or high prolactin levels deserve special attention regarding the possibility of PSIS. Furthermore, we emphasize the importance of regular follow-up and monitoring for multiple pituitary hormone deficiencies in all patients with a single pituitary hormone deficiency.

Pituitary Stalk Thickening: Causes and Consequences. The Children's Memorial Health Institute Experience and Literature Review.

Background: Pituitary stalk thickening (PST) is a rare abnormality in the pediatric population. Its etiology is heterogeneous. The aim of the study was to identify important clinical, radiological and endocrinological manifestations of patients with PST and follow the course of the disease. Materials and Methods: It is a study conducted in 23 patients (13 boys) with PST with/without central diabetes insipidus (CDI) diagnosed between 1990 and 2020 at Children's Memorial Health Institute (CMHI) in Warsaw, Poland. We analyzed demographic data, clinical signs and symptoms, radiological findings, tumor markers, hormonal results, treatment protocols and outcomes. Results: The median age at the diagnosis of PST was 9.68 years (IQR: 7.21-12.33). The median time from the onset of the symptoms to the diagnosis was 2.17 years (IQR: 1.12-3.54). The most common initially reported manifestations were polydipsia, polyuria and nocturia (82.6%); most of the patients (56.5%) also presented decreased growth velocity. Hormonal evaluation at the onset of PST revealed: CDI (91.3%), growth hormone deficiency (GHD) (56.5%), hyperprolactinemia (39%), central hypothyroidism (34.8%), adrenal insufficiency (9%), precocious puberty (8.7%). The majority of the patients were diagnosed with germinoma (seventeen patients - 73.9%, one of them with teratoma and germinoma). Langerhans cell histiocytosis (LCH) was identified in three patients (multisystem LCH in two patients, and unifocal LCH in one patient). A single case of atypical teratoid rhabdoid tumor, suspected low-grade glioma (LGG) and lymphocytic infundibuloneurohypophysitis (LINH). The overall survival rate during the observational period was 87.0%. Conclusions: The pituitary infundibulum presents a diagnostic imaging challenge because of its small size and protean spectrum of disease processes. Germinoma should be suspected in all children with PST, especially with CDI, even when neurological and ophthalmological symptoms are absent.

Case Report: Acquired Generalized Anhidrosis Caused by Brain Tumor: Review of the Literature.

Purpose: There has been limited focus on sweating failure in patients with brain tumor. We report two patients with generalized anhidrosis caused by germinoma. We also review previous reports of generalized anhidrosis due to brain tumor. Case Reports: Patient 1 was a 12-year-old boy with repetitive heat shock-like episodes even in winter. Based on Minor's test, he was diagnosed with generalized anhidrosis. Magnetic resonance imaging (MRI) revealed the absence of high signal intensity of the posterior pituitary. He was initially diagnosed with central diabetes insipidus. However, an MRI scan performed after 3 months revealed an enlarged pituitary stalk. He was finally diagnosed with germinoma by pituitary biopsy. After chemotherapy and radiation, sweating was partially resolved. Patient 2 was a 12-year-old girl with growth hormone deficiency and generalized anhidrosis. She was diagnosed with germinoma based on MRI and pituitary biopsy findings. After chemotherapy and radiation, the sweating resolved completely. Discussion: In our literature search, we identified four patients with anhidrosis due to brain tumor, including our cases. All patients had germinoma and continued to require hormone replacement therapy after treatment of germinoma. Two patients with incomplete recovery of sweating had the involvement in the hypothalamus, whereas one patient with complete recovery showed a lack of evident hypothalamic involvement. Improvement in sweating in one patient was not described. Conclusion: Germinoma can cause anhidrosis, and involvement in the hypothalamus may be relevant to incomplete recovery of sweating.

Pituitary stalk thickening in patients under 18 years of age - the most common causes and diagnostic procedures.

INTRODUCTION: Pituitary stalk thickening (PST) is a rare abnormality in children, and it may be challenging due to its diverse clinical picture. AIM OF THE STUDY: The aim of the study is to summarize the data on the causes and diagnostic procedures of PST. MATERIAL AND METHODS: Papers were searched in the PubMed database identifying published randomized clinical trials, reviews, systematic reviews, meta-analyses, and case reports. RESULTS: The most common causes of a thickened pituitary stalk in children are germ cell tumours (GCTs), Langerhans cell histiocytosis (LCH), and lymphocytic infundibulo-neurohypophysitis (LINH). Neurosarcoidosis, pituitary tuberculosis, granulomatosis, or specific inflammations were only reported in the paediatric population as case studies. PST mainly affects teenagers and is often detected with brain magnetic resonance imaging (MRI) in patients with central diabetes insipidus (CDI). It is not possible to differentiate the causes of PST with the use of the MRI image alone. Although various biochemical and oncological markers and other imaging tests are used, the diagnosis of PST remains a significant diagnostic challenge for clinicians. The final diagnosis is made based on histopathological examination. The indications for a biopsy are not uniform. Most experts, including the authors of the 2021 British consensus, recommend biopsy in the case of PST with a stalk lesion diameter ≥ 6.5-7 mm. CONCLUSIONS: The differential diagnosis of PST is a challenge. The diagnostic and treatment strategy should be individually adapted. Patients should be diagnosed in large clinical centres with experience in this field.

Relationship between growth hormone deficiency and nonalcoholic fatty liver disease in patients with pituitary stalk interruption syndrome.

BACKGROUND: Pituitary stalk interruption syndrome (PSIS), characterized by thinning or disappearance of the pituitary stalk, hypoplasia of the anterior pituitary, and an ectopic posterior pituitary, can lead to congenital combined pituitary hormone deficiency. There is a high prevalence of various metabolic disorders, including nonalcoholic fatty liver disease (NAFLD), in this population. OBJECTIVE: To investigate the characteristics of NAFLD in Chinese adult patients with PSIS and its association with growth hormone deficiency. DESIGN: Retrospective cross-sectional study in a tertiary referral center of China. PATIENTS: Adult patients with PSIS diagnosed, followed up between September 2019 and August 2021, were consecutively enrolled. MEASUREMENTS: Abdominal ultrasonography images were evaluated and noninvasive fibrosis scores were determined to assess the severity of NAFLD. Anthropometric, clinical, and biochemical parameters were compared between patients with and without NAFLD. Logistic regression was performed to assess the independent effects of insulin-like growth factor-1 (IGF-1) on NAFLD. RESULTS: A total of 93 patients (77 men, 16 women, mean age: 29.6 ± 7.1 years) were included. The prevalence of NAFLD and advanced fibrosis/cirrhosis was 50.5% and 4.3%, respectively. Insufficient hormone therapy and prominent metabolic disorders, including central obesity, dyslipidemia, insulin resistance, and metabolic syndrome, were more common in the NAFLD (+) group. After adjusting for multiple variables, IGF-1 <-2 standard deviation score (SDS) was found to be associated with an increased prevalence of NAFLD (odds ratio [OR]: 4.92, 95% confidence interval [CI]: 1.21-24.55, p = .035). Per 1 SDS increase in IGF-1 was associated with a 27% lower risk of NAFLD (OR: 0.73, 95% CI: 0.52-0.97, p = .042). CONCLUSION: NAFLD is a frequent comorbidity among Chinese adult patients with PSIS and is strongly associated with lower IGF-1 levels. Timely and appropriate hormone replacement, particularly growth hormone may contribute to decreasing the risk of NAFLD in these patients.

Differential Diagnosis and Radiographic Imaging of Pituitary Lesions: An Integrated Approach.

The sellar and parasellar region of the skull base is an area that can harbor a broad range of pathologic conditions. Formulating a differential diagnosis of a lesion in this region relies heavily on neuroimaging in addition to clinical and laboratory data. In this article, the authors briefly discuss some of the common pathologic conditions and their associated radiographic and clinical features.

A rare case of a secondary pituitary abscess arising in a craniopharyngioma with atypical presentation and clinical course.

Pituitary abscesses are very uncommon. They are divided into primary, arising within a healthy gland, and secondary, observed with an underlying pre-existing lesion. Here we present the eighth case reported of a secondary abscess within a craniopharyngioma. A 59-year-old-woman presented with a 3-week history of headache, and fever. Physical examination was unremarkable. An Magnetic Resonance Imaging (MRI) showed a pituitary lesion suggestive of a chronic inflammatory process. She was diagnosed with lymphocytic meningitis with hypophysitis and she was treated with corticosteroids. Two months later she presented with headache and fever again. Control MRI showed enlargement of the pituitary lesion. Therefore, a transsphenoidal biopsy was performed. During the procedure, purulent material was released. Histological study demonstrated a craniopharyngioma and meningeal inflammation. Empiric antibiotics were started. Three months post-operatively, a follow-up MRI showed a suspect minimal residual mass. Secondary pituitary abscesses are rare. The key to successful management is a high index of suspicion. Transsphenoidal surgical evacuation plus antibiotics is the mainstay of treatment. Although most symptoms resolve, endocrinopathies improve only rarely.

Pituitary MRI Standard and Advanced Sequences: Role in the Diagnosis and Characterization of Pituitary Adenomas.

Pituitary adenomas (PAs) represent the most frequently found lesions in the sellar region; however, several other lesions may be encountered in this region, such as meningiomas, craniopharyngiomas, and aneurysms. High-quality imaging is fundamental for diagnosis, characterization, and guidance of treatment planning of PAs. Sellar magnetic resonance imaging (MRI) is considered the imaging modality of choice for the evaluation of lesions in the sella turcica. The sellar MRI standard protocol includes coronal and sagittal T1-weighted spin-echo sequencing with and without gadolinium-based contrast agent and coronal T2-weighted (T2w) fast-spin echo sequencing. A systematic MRI approach to the pituitary region generally provides information that includes the size and shape of the PA, the presence of cysts or hemorrhage within the tumor, its relationship with the optic pathways and surrounding structures, potential cavernous sinus invasion, sphenoid sinus pneumatization type, and differential diagnosis with other sellar lesions. The standard protocol is sufficient for the evaluation of most cases; however, some advanced techniques (susceptibility imaging, diffusion-weighted imaging, 3D T2w high-resolution sequences, magnetic resonance elastography, perfusion-weighted imaging) may render additional information, which may be important for some cases. In this "approach to the patient" manuscript, we will discuss the use of standard and advanced MRI sequences in the diagnosis and characterization of PAs, including MRI features associated with treatment response that may aid in presurgical evaluation and planning, and red flags that may point to an alternative diagnosis.