Perineural spread (PNS) along the mandibular division (V3) of the trigeminal nerve is an important prognostic finding in head and neck malignancies that leads to disease upstaging and treatment intensification. Histologic confirmation traditionally requires invasive open biopsy or challenging CT/fluoroscopically guided access through foramen ovale, which carries risks of hemorrhage, infection, and trigeminocardiac reflex activation. We describe a CT-guided transcondylar approach using the styloid-pterygoid line as an anatomic landmark to safely access the mandibular nerve within the infratemporal fossa. Six patients with head and neck malignancies demonstrating MRI findings suggestive of V3 PNS between 2015 and 2024 underwent CT-guided transcondylar needle biopsy targeting the abnormal mandibular nerve using the styloid-pterygoid line for anatomic localization. Technical success was achieved in all cases (100%). Histologic confirmation of malignant PNS was obtained in five patients (83%), directly leading to escalation of treatment, while one patient showed inflammatory changes without malignancy, with subsequent MRI demonstrating improvement in nerve imaging that validated the benign biopsy result. No procedural complications occurred. The CT-guided transcondylar approach using the styloid-pterygoid line provides a safe, effective, and reproducible method for tissue diagnosis of suspected V3 perineural spread. By targeting the mandibular nerve within the infratemporal fossa rather than at the skull base, this technique mitigates procedural risks while maintaining diagnostic yield. This technique should be considered when histologic confirmation of mandibular nerve involvement is required, and tissue diagnosis would alter clinical management. SUMMARY: CT-guided transcondylar approach utilizing the styloid-pterygoid line represents a safe, effective, and reproducible technique for obtaining tissue diagnosis of suspected mandibular nerve perineural spread. This method offers a minimally invasive alternative to foramen ovale puncture or open surgical biopsy, avoiding the risks associated with such interventions while maintaining high diagnostic yield. In patients with head and neck malignancy and imaging findings suggestive of V3 PNS, this approach should be considered as a diagnostic strategy to facilitate timely, accurate histologic confirmation and optimize therapeutic decision-making.

Abstract From 1990 to 2024, women neuroradiologists in North America have made tremendous progress in the areas of leadership, clinical innovation, research, education, diversity, equity and inclusion, and global outreach. This chapter begins with summaries of their key accomplishments in four broad domains, followed by short biographical sketches of numerous luminaries organized by leadership roles and areas of expertise, and ending with conclusions and future directions.

BACKGROUND AND PURPOSE:Assessment of cavernous sinus (CS) invasion is of paramount importance in planning the surgical treatment of pituitary neuroendocrine tumors (PitNET). The most widely used classification - the Knosp grading system - has limitations that lead to highly variable prediction of true CS invasion, and low interobserver agreement. We set out to develop a classification system to address these limitations. MATERIALS AND METHODS:The CLIPS classification was developed by evaluating each CS compartment (Lateral, Inferior, Posterior, Superior, and Clinoidal space). For each compartment, a single line bisecting the carotid artery, following anatomical planes, was used to grade the lateral extension of the PitNET. Tumors medial to these lines were graded as 0, and those lateral to it were graded as 1 for a given compartment or space. This classification was used to evaluate 255 patients (510 CS) who underwent transsphenoidal endoscopic endonasal approach (EEA) surgery, either with transcavernous extension (TC-EEA group = 139 CS) or without it (EEA group = 371 CS). Compartmental invasion was validated by intraoperative assessment in the TC-EEA group, and by postoperative MRI in the EEA group. Results were compared with the Knosp classification, stratified by the presence of apoplexy, functional status, and previous surgery. Inter-observer agreement (IOA) was calculated in a sample of these cases. RESULTS:Cavernous sinus compartment invasion was present in 19.4% of CS and 37% of patients. CLIPS classification yielded an overall sensitivity of 90.8% (95% CI 86.6-94%), specificity of 98.4% (95% CI 97.8-98.9%), PPV of 86.5% (95% CI 82.3-89.8%), NPV of 99% (95% CI 98.5-99.3%), and accuracy of 97.6% (95% CI 96.9-98.2%) for predicting invasion, with comparable results in all compartments. Previous surgery increased the rate of invasion for CLIPS grade 0 in the superior and posterior compartments, as well as in Knosp grade 2 cases. IOA was almost perfect for superior and inferior compartments, and substantial for lateral, posterior, and clinoidal space. Knosp classification achieved only moderate agreement. CONCLUSIONS:The CLIPS classification provides a reliable and accurate tool to evaluate CS compartment invasion by PitNET, incorporating the assessment of each CS compartment to better assist pituitary surgeons.

BACKGROUND AND PURPOSE:Gadopiclenol is a next-generation macrocyclic gadolinium-based contrast agent (GBCA) distinguished by its high T1 relaxivity and kinetic stability. It was developed to address the clinical need for reduced gadolinium dosing while maintaining high diagnostic accuracy, thereby minimizing potential long-term risks associated with gadolinium retention. Although various neuroradiology applications have been explored, the potential benefits of gadopiclenol's increased T1 relaxivity have not been investigated for the purpose of evaluating endolymphatic hydrops (EH) using delayed contrast-enhanced inner ear imaging. MATERIALS AND METHODS:We prospectively enrolled 26 consecutive patients at our institution's otology clinic based on the 2015 American Academy of Otolaryngology-Head and Neck Surgery criteria for Ménière disease (MD), including acute or fluctuating symptoms of vertigo, hearing loss, tinnitus, or aural fullness. Each patient underwent 4-hour delayed contrast-enhanced inner ear imaging at 3T with half-dose (0.05 mmol/kg) GBCA administration using gadopiclenol. The contrast-to-noise ratio (CNR) and SNR were determined. Assessment of blood-labyrinthine barrier permeability, utricle-saccule discrimination, and endolymphatic hydrops was performed by 2 head and neck neuroradiologists. Image quality, SNR, and CNR were compared with previously published data that utilized the same technical parameters with a contrast dose of 0.1 mmol/kg. RESULTS:Fifty-one ears were analyzed. One ear was excluded based on a prior history of left labyrinthectomy after failed medical management of MD. There were 31 symptomatic and 20 asymptomatic ears determined by clinical and hearing evaluation. Delayed contrast-enhanced inner ear imaging with gadopiclenol at 0.05 mmol/kg provided comparable CNR and SNR to gadobenate dimeglumine at 0.1 mmol/kg, with no statistically significant difference (P > .05). There was excellent interobserver agreement for the grading EH (κ > 0.80). CONCLUSIONS:Our study demonstrates that 3D-FLAIR inner ear imaging using gadopiclenol at 0.05 mmol/kg is a reliable method for detecting clinically concordant EH and that image quality, based on qualitative and quantitative metrics, is comparable with a previously published study using gadobenate dimeglumine at a single-dose of 0.1 mmol/kg.

Abstract Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by renal phosphate wasting and impaired bone mineralization secondary to secretion of fibroblast growth factor 23 (FGF23) from mesenchymal tumors (phosphaturic mesenchymal tumors, PMTs). PMTs have wide anatomical distribution but typically affect extremities and craniofacial bones. Diagnosis of TIO/PMT is often delayed, and a high index of suspicion is essential in patients with unexplained fractures, but many physicians lack familiarity with TIO/PMT and simply attribute fractures to the more common diagnosis of osteoporosis. We present 5 cases of TIO, with 4 having long histories of multiple insufficiency fractures prior to recognition of TIO and localization of a PMT. Four patients were treated surgically, while 1 preferred medical management. Two patients had lesions localized to the skull base, both of which showed marked hypervascularity on arterial spin label perfusion imaging. Thus, arterial spin label may not only help to localize these tumors, but may also be a helpful supplemental imaging finding in supporting this diagnosis. PMT should be considered in the differential diagnosis for hypervascular skull base masses, especially if the patient has any history of insufficiency fracture or imaging evidence of osteopenia, as early diagnosis of TIO can help prevent disabling complications.

The goal of this international survey was to understand how diffusion (DWI) and perfusion imaging (PWI) are being applied to clinical head and neck imaging. An online questionnaire focusing on acquisition, clinical indications, analysis, and reporting of qualitative DWI (QlDWI), quantitative DWI (QnDWI) and dynamic contrast-enhanced PWI (DCE-PWI) in the head and neck was circulated to members of the American Society of Head and Neck Radiology (ASHNR) and European Society of Head and Neck Radiology (ESHNR) over a 3-month period. Descriptive statistics and group comparisons were calculated with SPSS® v27. There were 294 unique respondents (17.6

BACKGROUND AND PURPOSE:Technical advancements in inner ear MRI promise improved diagnosis and management of Ménière disease (MD), but a key challenge in optimizing 3D-FLAIR protocols for inner ear imaging lies in selecting the optimal flip angle. This study evaluates the 3 most common flip angle parameters used in 3D-FLAIR imaging for MD through a prospective, head-to-head comparison of image quality at constant flip angle (CFA) 120°, CFA 140°, and variable flip angle (VFA) obtained 4 hours after IV administration of a single-dose gadolinium-based contrast agent. MATERIALS AND METHODS:We prospectively enrolled 16 consecutive patients at our institution's otology clinic on the basis of the 2015 American Academy of Otolaryngology-Head and Neck Surgery criteria for MD, including acute or fluctuating symptoms of vertigo, hearing loss, tinnitus, or aural fullness. Each patient underwent delayed inner ear MRI at 3T with the 3 most commonly used flip angles: CFA 120°, CFA 140°, and VFA. The contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were determined for each flip angle. Assessment of blood-labyrinthine barrier (BLB) permeability, utricle-saccule discrimination, and endolymphatic hydrops (EH) was performed by 2 head and neck neuroradiologists. RESULTS:Thirty-one ears were analyzed. One ear was excluded on the basis of a prior history of left labyrinthectomy after failed medical management of MD. There were 17 symptomatic and 14 asymptomatic ears determined by clinical and hearing evaluation. The SNR of the perilymphatic space and CNR of the endolymphatic space were significantly higher at CFA 140°, followed by CFA 120°, and then VFA (P < .05). There was significantly improved visualization of EH, the utricle-saccule complex, and BLB permeability at CFA 140° (P < .05), with excellent interobserver agreement (κ > 0.80). CONCLUSIONS:Our study demonstrates that 3D-FLAIR inner ear imaging using CFA 140° and single-dose IV gadolinium contrast at 3T is a reliable method for detecting EH.

OBJECTIVE:With their growing experience in endoscopic transcavernous approaches, the authors have observed that pituitary adenomas have distinct patterns of invasion into the medial wall of the cavernous sinus (MWCS). In this study, they aimed to describe the different patterns of MWCS invasion and their relevance for pituitary surgery. METHODS:Based on a review of 144 patients with 159 cavernous sinus (CS) explorations, the authors described three patterns of MWCS invasion: focal invasion, wall thickening, and wall destruction. Demographics, previous surgery, size, hormonal status, consistency, CS compartment invasion, invasion of the carotico-clinoid ligament (CCL), carotid adherence, gross-total resection (GTR) of intracavernous tumor, endocrinological remission (ER), and complications (vascular injury, cranial nerve palsy, CSF leakage, and hematoma) were evaluated. RESULTS:The most frequent pattern of MWCS invasion was wall destruction (47.2%), followed by wall thickening (28.9%) and focal invasion (23.9%). All cases of focal invasion were contained within the wall, whereas 59% of the wall-thickening and 100% of the wall destruction cases had intracavernous tumor (p < 0.001). Overall, GTR was achieved in 87.4% of cases and ER was achieved in 80.6% with surgery alone. Focal invasion was most associated with functioning adenomas (92%) and low Knosp grade (95%). Invasion of the CCL, adherence of the MWCS to the carotid artery, and fibrous consistency were found in 15%-20% of cases. GTR was achieved in all cases and ER in 93% with no complications associated with MWCS resection. Wall thickening was also found predominantly in functioning adenomas (83%) with low Knosp grade (72%), and often in recurrent cases (46%). Carotid adhesion was significantly more frequent (61%), as was CCL invasion (44%) and fibrous consistency (46%). GTR was achieved in 98% and ER in 82%, with transient postoperative diplopia in 7% of cases, all with intracavernous tumor. Wall destruction occurred almost exclusively in macroadenomas (96%) with high Knosp grades (59%) and no hormonal secretion (55%). Invasion of the CCL, fibrous consistency, and carotid adherence were found in less than one-third of the cases. GTR was achieved in 75% and ER in 65%, with postoperative diplopia in 11% of cases. CONCLUSIONS:Pituitary adenomas may invade the MWCS in three distinct patterns, each with particular tumor characteristics and a differential degree of technical difficulty and clinical outcomes.

Objective To assess magnetic resonance imaging (MRI) safety of stapes prostheses. Data Sources Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Web of Science, and Scopus databases were searched from inception to November 2021 following PRISMA guidelines. Review Methods Studies reporting evidence of stapes prosthesis displacement or interaction in adult or pediatric implant recipients undergoing MRI. Cadaveric, animal, and basic studies with nonhuman data were also included. Results From an initial search of 123 articles, 42 full-text studies were evaluated for eligibility and 19 studies that met the inclusion criteria were included. Motion artifact was reported in a few stainless steel prosthesis types in vitro; however, such displacement was not observed in human cadaver temporal bone studies and had no adverse reported outcomes. A small subgroup of patients in the 1980s received a ferromagnetic stainless steel stapes implant that was recalled and has not been used since 1987. Patients with implants performed in the 1980s should be directed to 1.5T scanners from an abundance of caution. Conclusion Modern (post-1987) stapes prostheses do not pose a risk in vivo when exposed to the magnetic fields of MRI scanners.

A 61-year-old woman with HIV and diabetes mellitus presented with right vision loss due to invasive rhino-orbito-cerebral mucormycosis. The disease progressed into the cavernous sinus and along trigeminal nerve branches despite initial surgery and antifungal therapy. As she did not pass a BTO, we performed a STA-to-MCA bypass, followed by a middle fossa approach for cavernous sinus exenteration, resulting in successful disease control. This case illustrates the technical nuances of cavernous sinus exenteration.

Purpose: To determine the sensitivity of brain magnetic resonance imaging (MRI) in the detection of choroidal metastasis (CM) from systemic primary cancers. Methods: A retrospective chart review identified patients with clinically confirmed CM seen on the Oncology Service (Byers Eye Institute) between January 2018 and March 2022. Patients had an MRI brain and/or orbits performed within 3 months of CM diagnosis. Evaluation of CM detection by MRI was then divided into two parts: an initial “standard read,” where determination of CM detection was based solely on the original radiology report, to reflect real-world performance, and a subsequent “dedicated read,” for which a board-certified neuroradiologist, blinded to the laterality and location of the CM, re-evaluated the studies to provide an objective “gold standard” interpretation regarding the radiographic detection of CM. Results: The study included 42 eyes of 40 patients with confirmed CM. On standard read, MRI detection of CM occurred in 21 of 42 eyes (50%), with no significant difference between MRI brain and orbit protocols (p=0.249). Features associated with improved detection were increased tumor basal diameter (p<0.001) and ultrasonographic tumor thickness (p=0.003). On dedicated read, MRI detection of CM improved to 26 of 33 eyes (76%). Post-gadolinium 3D FLAIR sequence was the most sensitive (88%) for CM detection. 42% and 58% of lesions were visualized using conventional pre-gadolinium T1- and T2-weighted imaging, respectively. Conclusions: MRI sensitivity improved from 50% to 76% with focused reinterpretation. Increased utilization of the FLAIR sequence and increased ocular scrutiny may contribute to earlier diagnosis of CM.

Introduction:The objective of this study was to determine the sensitivity of brain magnetic resonance imaging (MRI) in the detection of choroidal metastasis (CM) from systemic primary cancers.Methods:A retrospective chart review identified patients with clinically confirmed CM seen on the Oncology Service (Byers Eye Institute) between January 2018 and March 2022. Patients had an MRI brain and/or orbits performed within 3 months of CM diagnosis. Evaluation of CM detection by MRI was then divided into two parts: an initial "standard read," where determination of CM detection was based solely on the original radiology report, to reflect real-world performance, and a subsequent "dedicated read," for which a board-certified neuroradiologist, blinded to the laterality and location of the CM, reevaluated the studies to provide an objective "gold standard" interpretation regarding the radiographic detection of CM.Results:The study included 42 eyes of 40 patients with confirmed CM. On standard read, MRI detection of CM occurred in 21 of 42 eyes (50%), with no significant difference between MRI brain and orbit protocols (p = 0.249). Features associated with improved detection were increased tumor basal diameter (p < 0.001) and ultrasonographic tumor thickness (p = 0.003). On dedicated read, MRI detection of CM improved to 26 of 33 eyes (76%; limited to eyes with full complement of pre- and post-gadolinium sequences). Post-gadolinium 3D fluid-attenuated inversion recovery (FLAIR) sequence with fat suppression was the most sensitive (88%) for CM detection. 42% and 58% of lesions were visualized using conventional pre-gadolinium T1- and T2-weighted imaging, respectively.Conclusions:MRI sensitivity to detect CM improved from 50% to 76% with focused reinterpretation. Increased utilization of the post-gadolinium 3D FLAIR sequence and increased ocular scrutiny in cancer patients undergoing brain imaging may facilitate earlier diagnosis of CM.

OBJECTIVE:The short T2 nature of cortical bone causes it to appear similar to air on MR, forcing clinicians to rely on computed tomography imaging, with its attendant ionizing radiation exposure, to define temporal bone structures. Through the use of novel MR sequences with ultra-short echo times (UTE), short T2 structures are now able to be visualized, allowing for improved understanding of anatomical relationships. METHODS:Eight patients (50% female) undergoing MR imaging of the skull base for diagnostic purposes (62.5% for vestibular schwannoma surveillance) at a tertiary care center were enrolled to evaluate the safety and efficacy of UTE imaging. CT scans were completed in 37.5% of the patients as part of their workup and used for comparison purposes. The repetition time, short echo time, and long echo time for the UTE sequence were 11, 0.032, and 2.2 msec, respectively. RESULTS:The protocol added 6 min to the total scanning time, and all patients tolerated the sequence without issue. The ossicles, mastoid air cells, antrum, and epitympanum were able to be seen and had a high Dice similarity coefficient when compared to CT (>0.5). UTE allowed for clear delineation of all segments of the facial nerve with a signal-to-noise ratio of 35 (although the BRAVO sequences had a superior ratio of 140). Vestibular schwannomas were able to be distinguished from normal brain parenchyma. CONCLUSIONS:UTE is safe and effective for visualizing anatomic structures not normally seen on traditional MRI, potentially allowing for improved surgical planning in patients. LEVEL OF EVIDENCE:3 Laryngoscope, 134:4691-4696, 2024.

Brain metastases occur in 1% of sarcoma cases and are associated with a median overall survival of 6 months. We report a rare case of a brain metastasis with unique radiologic and histopathologic features in a patient with low grade fibromyxoid sarcoma (LGFMS) previously treated with immune checkpoint inhibitor (ICI) therapy. The lone metastasis progressed in the midbrain tegmentum over 15 months as a non-enhancing, T2-hyperintense lesion with peripheral diffusion restriction, mimicking a demyelinating lesion. Histopathology of the lesion at autopsy revealed a rich infiltrate of tumor-associated macrophages (TAMs) with highest density at the leading edge of the metastasis, whereas there was a paucity of lymphocytes, suggestive of an immunologically cold environment. Given the important immunosuppressive and tumor-promoting functions of TAMs in gliomas and carcinoma/melanoma brain metastases, this unusual case provides an interesting example of a dense TAM infiltrate in a much rarer sarcoma brain metastasis.

BACKGROUND AND PURPOSE:Overuse of CT-based cerebrovascular imaging in the emergency department and inpatient settings, notably CTA of the head and neck for minor and nonfocal neurologic presentations, stresses imaging services and exposes patients to radiation and contrast. Furthermore, such CT-based imaging is often insufficient for definitive diagnosis, necessitating additional MR imaging. Recent advances in fast MRI may allow timely assessment and a reduced need for head and neck CTA in select populations. MATERIALS AND METHODS:We identified inpatients or patients in the emergency department who underwent CTAHN (including noncontrast and postcontrast head CT, with or without CTP imaging) followed within 24 hours by a 3T MRI study that included a 2.5-minute unenhanced multicontrast sequence (NeuroMix) and a 5-minute intracranial time of flight MRA) during a 9-month period (April to December 2022). Cases were classified by 4 radiologists in consensus as to whether NeuroMix and NeuroMix + MRA detected equivalent findings, detected unique findings, or missed findings relative to CTAHN. RESULTS:One hundred seventy-four cases (mean age, 67 [SD, 16] years; 56% female) met the inclusion criteria. NeuroMix alone and NeuroMix + MRA protocols were determined to be equivalent or better compared with CTAHN in 71% and 95% of patients, respectively. NeuroMix always provided equivalent or better assessment of the brain parenchyma, with unique findings on NeuroMix and NeuroMix + MRA in 35% and 36% of cases, respectively, most commonly acute infarction or multiple microhemorrhages. In 8/174 cases (5%), CTAHN identified vascular abnormalities not seen on the NeuroMix + MRA protocol due to the wider coverage of the cervical arteries by CTAHN. CONCLUSIONS:A fast MR imaging protocol consisting of NeuroMix + MRA provided equivalent or better information compared with CTAHN in 95% of cases in our population of patients with an acute neurologic presentation. The findings provide a deeper understanding of the benefits and challenges of a fast unenhanced MR-first approach with NeuroMix + MRA, which could be used to design prospective trials in select patient groups, with the potential to reduce radiation dose, mitigate adverse contrast-related patient and environmental effects, and lessen the burden on radiologists and health care systems.

CT, MRI, and FDG PET/CT play major roles in the diagnosis, staging, treatment planning, and surveillance of head and neck cancers. Nonetheless, an evolving understanding of head and neck cancer pathogenesis, advances in imaging techniques, changing treatment regimens, and a lack of standardized guidelines have led to areas of uncertainty in the imaging of head and neck cancer. This narrative review aims to address four issues in the contemporary imaging of head and neck cancer. The first issue relates to the standard and advanced sequences that should be included in MRI protocols for head and neck cancer imaging. The second issue relates to approaches to surveillance imaging after treatment of head and neck cancer, including the choice of imaging modality, the frequency of surveillance imaging, and the role of standardized reporting through the Neck Imaging Reporting and Data System. The third issue relates to the role of imaging in the setting of neck carcinoma of unknown primary. The fourth issue relates to the role of simultaneous PET/MRI in head and neck cancer evaluation. The authors of this review provide consensus opinions for each issue.

Abstract Metastases from extra-CNS sites typically enhance on MR after the administration of gadolinium-based contrast agents due to disruption of the blood-brain barrier. Fibromyxoid sarcoma involving the brain is extremely rare, with only a few reported cases manifesting as well-circumscribed enhancing masses. Here, we report an extremely rare non-enhancing brain metastasis secondary to an already rare sarcoma. A 44-year-old woman with gluteal fibromyxoid sarcoma metastatic to cervical paraspinal muscles and adrenal gland treated with ipilimumab/nivolumab presented with diplopia and was found to have an 8 mm T2-hyperintense midbrain lesion without enhancement or mass effect. An inflammatory etiology associated with checkpoint inhibitor therapy was suspected, and she was treated with IV methylprednisolone 1 g daily for 3 days followed by an oral prednisone taper, IV immunoglobulin, and plasma exchange without improvement. The midbrain lesion steadily grew over 15 months of follow up, eventually involving the bilateral medial thalami and demonstrating diffusion restriction in the midbrain, but never showing gadolinium enhancement. The imaging was reminiscent of peripheral brainstem non-enhancing band-like lesions reported in leptomeningeal lung cancer, however CSF cytology was repeatedly normal, as was extensive infectious and inflammatory testing. Her neurologic disability continued to progress, with development of bilateral oculomotor nerve palsies, dysarthria, and depressed level of alertness, devolving into non-convulsive status epilepticus requiring intubation. She died six months after onset of neurologic symptoms. At autopsy, histologic and immunohistochemical evaluation revealed fibromyxoid sarcoma (MUC-4 positive, TAOK1-FUS fusion) centered on the periventricular aqueduct with accompanying disseminated single-cell infiltration throughout the midbrain. The background midbrain and periventricular parenchyma were notable for voluminous microglial activation and histiocytic infiltrate. In sum, this case represents a radiographically unique sarcoma brain metastasis which on pathologic exam showed robust inflammatory changes far out of proportion to the tumor present.

BACKGROUND Schizencephaly is an uncommon central nervous system malformation. Intracranial lipomas are also rare, accounting for approximately 0.1% of brain “tumors.” They are believed to be derived from a persistent meninx primitiva, a neural crest–derived mesenchyme that develops into the dura and leptomeninges. OBSERVATIONS The authors present a case of heterotopic adipose tissue and a nonshunting arterial vascular malformation arising within a schizencephalic cleft in a 22-year-old male. Imaging showed right frontal gray matter abnormality and an associated suspected arteriovenous malformation with evidence of hemorrhage. Brain magnetic resonance imaging revealed right frontal polymicrogyria lining an open-lip schizencephaly, periventricular heterotopic gray matter, fat within the schizencephalic cleft, and gradient echo hypointensity concerning for prior hemorrhage. Histological assessment demonstrated mature adipose tissue with large-bore, thick-walled, irregular arteries. Mural calcifications and subendothelial cushions suggesting nonlaminar blood flow were observed. There were no arterialized veins or direct transitions from the arteries to veins. Hemosiderin deposition was scant, and hemorrhage was not present. The final diagnosis was consistent with ectopic mature adipose tissue and arteries with meningocerebral cicatrix. LESSONS This example of a complex maldevelopment of derivatives of the meninx primitiva in association with cortical maldevelopment highlights the unique challenges from both a radiological and histological perspective during diagnostic workup.