Left Temporal Lesion Research Articles

SURG-02. ANAPLASTIC PLEOMORPHIC XANTHOASTROCYTOMA WITH LEPTOMENINGEAL DISSEMINATION PRESENTING WITH CRANIAL NEUROPATHY IN AN ADULT PATIENT: ILLUSTRATIVE CASE AND REVIEW OF THE LITERATURE

Abstract INTRODUCTION Anaplastic pleomorphic xanthoastrocytomas (APXA) are very rare, grade III malignant astrocytic glial neoplasms first described as a distinct entity in the 2016 World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS). They are generally seen in pediatric and young adult patients as supratentorial lesions with both solid and cystic components and have a high propensity for recurrence despite local treatment. APXAs occasionally demonstrate leptomeningeal dissemination (LMD) but extremely seldom at the time of diagnosis. They are typically treated via surgical resection with adjuvant chemoradiation, although there is no standard of care for adjuvant therapy. Case Presentation: The authors describe the case of a 37-year-old male with a history of seizures since age 11 who presented with four months of worsening headache, increasingly frequent seizures, and diplopia with right cranial nerve III palsy. Imaging at the time of diagnosis of his seizure disorder as a child demonstrated a small left temporal lesion, which remained stable on imaging for over 20 years and was never biopsied, however MRI at current presentation showed significant interval enlargement with intralesional hemorrhage and leptomeningeal enhancement involving the left temporal and parietal lobes, left internal auditory canal, and right oculomotor nerve. He underwent surgical resection with gross total resection achieved and pathology revealed WHO Grade III pleomorphic xanthoastrocytoma with ATG7::RAF1 fusion, 9p21 deletion, and TERT promoter mutation on next generation sequencing. This was followed by adjuvant whole brain radiation with boost and treatment with MEK inhibitor cobimetinib. His postoperative course was remarkable for intermittent speech difficulty and improving right third nerve palsy. CONCLUSION We describe the unusual presentation of an already exceedingly rare primary CNS tumor, namely APXA in an adult patient with LMD and cranial neuropathy at the time of diagnosis, and detail tailored adjuvant therapy based on genomic profiling.

NFS-19. ATYPICAL PRESENTATION OF GLIOMAS IN ADOLESCENTS WITH NEUROFIBROMATOSIS TYPE 1 (NF1): A CASE SERIES

Abstract BACKGROUND Patients with NF1 are at risk for developing gliomas, usually low-grade in childhood but may be high-grade in adults. In children, the most common sites of disease are the optic pathway and brainstem; tumors in these regions often arise in young children and display histological features characteristic of pilocytic astrocytoma (PA) when biopsied. Typical MRI findings include T2 hyperintense, T1 hypointense lesions with minimal contrast enhancement and no diffusion restriction. Due to the well-established pattern of low-grade tumor formation in children with NF1, as well as the surgically challenging areas in which these tumors develop, low-grade glioma (LGG) therapy is often initiated without histologic confirmation of the diagnosis in classic cases. In cases with atypical disease location, older age at presentation or imaging appearance, a biopsy may be considered to exclude higher-grade lesions. METHODS Retrospective chart review, case series RESULTS Four adolescent patients with NF1 presented with atypical suspected gliomas. All four patients underwent surgical biopsy/resection. Case 1 was a left temporal lesion in the previous radiation field for optic pathway glioma; biopsy confirmed LGG with MAP2K1 mutation and increased focal proliferation index (28%), but methylation did not match with any established classification. The patient progressed through multiple rounds of therapy and succumbed to her tumor. Case 2 was a left occipital lesion; biopsy confirmed PA with CDKN2A deletion. The tumor displayed rapid regrowth, but subsequently stabilized. Case 3 was a right frontal lesion; confirmed PA. The tumor demonstrated some regrowth but then stabilized. Case 4 was a basal ganglia lesion; confirmed PA. The patient has demonstrated stable MRI findings and has not required further intervention. CONCLUSIONS Biopsy yielded helpful prognostic information (additional mutations, proliferation rate) in half of these atypical cases. Biopsy should be carefully considered for NF1 patients with atypical presentation or a history of radiation.

Impairment of comprehension of items belonging to the semantic category of fruit in a patient presenting anomic aphasia due to a left temporal ischemic lesion

Impairment of comprehension of items belonging to the semantic category of fruit in a patient presenting anomic aphasia due to a left temporal ischemic lesion

Recurrent petit mal seizures in Erdheim-Chester disease mimicking an intra-axial brain tumor: illustrative case.

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis characterized histologically by foamy histiocytes and Touton giant cells in a background of fibrosis. Bone pain with long bone osteosclerosis is highly specific for ECD. Central nervous system involvement is rare, although dural, hypothalamic, cerebellar, brainstem, and sellar region involvement has been described. A 59-year-old man with a history of ureteral obstruction, medically managed petit mal seizures, and a left temporal lesion followed with serial magnetic resonance imaging (MRI) presented with worsening seizure control. Repeat MRI identified bilateral amygdala region lesions. Gradual growth of the left temporal lesion over 1 year with increasing seizure frequency prompted resection. A non-Langerhans cell histiocytosis with a BRAF V600E mutation was identified on pathology. Imaging findings demonstrated retroperitoneal fibrosis and long bone osteosclerosis with increased fluorodeoxyglucose uptake that, together with the neuropathologic findings, were diagnostic of ECD. This case of biopsy-proven ECD is unique in that the singular symptom was seizures well controlled with medical management in the presence of similarly located bilateral anterior mesial temporal lobe lesions. Although ECD is rare intracranially, its variable imaging presentation, including the potential to mimic seizure-associated medial temporal lobe tumors, emphasizes the need for a wide differential diagnosis.

P11.33.B A PATIENT WITH GLIOBLASTOMA AND EXTENSIVE EXTRANEURAL METASTASES - DOES MOLECULAR BIOLOGY PLAY A CRUCIAL ROLE?

Abstract BACKGROUND Extraneural metastases of glioblastoma (GBM) are rare, reported incidence in literature is 0.4% to 2%. There is a lack in epidemiological data, and what little exists is outdated. The most commonly reported sites of metastases are bone, lymph node and lung. There is an insufficient understanding of the biological mechanism of metastasis, nevertheless, surgical intervention and peritoneal seeding through a ventriculoperitoneal shunt have been postulated as rational routes for the tumor cells. However, reports show metastasizing GBM in patients where neither of these procedures have been performed and therefore biological aspects should be elucidated. Previously, some few genomic studies have shown high mutational burden and that some mutations are only detected in the metastases, indicating clonal evolution. Commonly TP53, TERT, PTEN and CDKN2A/B have been revealed as shared mutations. MATERIAL AND METHODS A 55-year-old man presented with approximately 2 months of progressive headache and behavioral changes. Brain MRI revealed a left temporal lesion suspicious of GBM and no extracranial metastasis was detected. The patient underwent near total surgical resection and completed Stupp protocol. Nine months later, he was admitted to the local hospital with reduced general condition, tachypneic and lower back pain, but subsequent CT of thorax and abdomen revealed multiple pathological lesions in mediastinum, bones, lung, soft tissue, and mesentery. MRI confirmed the findings and a large soft tissue lesion at the level of the 6th thoracic vertebrae, was biopsied and showed metastasis from GBM. There was also local progression of the primary tumor in the brain. Treatment strategy was changed to a combination of lomustine, vincristine and bevacizumab. It was collected blood samples from the patient in respect of circulating tumor cells. A molecular characterization of the tumor samples was performed. RESULTS The primary tumor was MGMT promotor methylated, IDH-1/-2 wildtype, had no TERT promotor mutation, TP53 wildtype and ATRX was intact. The biopsy of the paravertebral lesion showed infiltration of a low differentiated, highly cellular tumor. Immunohistochemically the tumor cells were positive for GFAP, OLIG2 and S100. The molecular features revealed no mutation in BRAF or NTRK. Interestingly, PD-L1 was extremely upregulated, may indicating a potential benefit of immune-checkpoint inhibitors for extraneural metastases. A literature survey is done to find out any risk factors for metastasis. CONCLUSION We report a rare case of GBM with extensive extraneural metastases. This underlines the importance of comparing molecular biology, localization, and other patient and tumoral factors in order to identify any specific risk factor for metastasis. In turn, helping to stratify the follow up of this subgroup in the future.

Cerebral Toxoplasmosis in a Previously Fit Individual – Pitfalls in Management – A Case Report.

Most people with toxoplasmosis infection are asymptomatic. Cerebral toxoplasmosis in HIV patient represents poor prognostic determinant, but treatable if early treatment is initiated. A case of delayed diagnosis of cerebral toxoplasmosis is presented. A 27-year-old man presented with one-sided facial numbness and treated as Bell’s Palsy. Later he developed slurred speech. Contrast enhanced CT brain showed left frontal temporal hypodense lesion, leptomeningeal enhancement and perilesional oedema. Steroid was started. Four days later, he presented with decreased responsiveness. Retroviral was detected and diagnosis changed to opportunistic brain infection. He died after 3 days. Toxoplasmosis IgG antibodies turned out positive. In diagnosing cerebral toxoplasmosis, clinical presentation and examination are as important as laboratory testing and radiological imaging.

A human T-lymphotropic virus-1 carrier who developed progressive multifocal leukoencephalopathy following immunotherapy for sarcoidosis: a case report

BackgroundProgressive multifocal leukoencephalopathy (PML) is a devastating demyelinating disorder of the central nervous system caused by opportunistic infection of the JC virus (JCV).Case presentationA 58-year-old Japanese woman was admitted to our hospital for aphasia. She had a 5-year history of untreated sarcoidosis and was a human T cell lymphotropic virus-1 (HTLV-1) carrier. Serum angiotensin-converting enzyme, soluble interleukin-2 receptor, lysozyme, and calcium levels were elevated. JCV-DNA was not detected in cerebrospinal fluid by PCR testing. Skin biopsy revealed noncaseating granuloma formation. Bilateral multiple nodular lesions were present on chest X-ray. Brain magnetic resonance imaging showed left frontal and temporal lesions without gadolinium enhancement. As we suspected that systemic sarcoidosis had developed into neurosarcoidosis, we started steroid and infliximab administration. After treatment, the chest X-ray and serum abnormalities ameliorated, but the neurological deficits remained. At 1 month after immunotherapy, she developed right hemiparesis. Cerebrospinal fluid was positive for prototype (PML-type) JCV on repeated PCR testing. Brain biopsy revealed demyelinating lesions with macrophage infiltration, atypical astrocytes, and JCV antigen-positive cells. We diagnosed her with PML and started mefloquine, leading to partial remission.ConclusionsSarcoidosis and HTLV-1 infection both affect T cell function, especially CD4+ T cells, and may developped the patient’s PML. The comorbidity of sarcoidosis, PML, and HTLV-1 infection has not been reported, and this is the world’s first report of PML associated with HTLV-1 infection and sarcoidosis.

PATH-40. A GIANT CELL LESION RESEMBLING REPARATIVE GIANT CELL GRANULOMA WITH FN1-TEK FUSION, IN THE SPECTRUM OF CALCIFIED CHONDROID MESENCHYMAL NEOPLASM?

Abstract A newly described entity called “calcified chondroid mesenchymal neoplasms” includes chondroid neoplasms with variable amounts of calcification and FN1 fusions [Liu et al, Mod Pathol 2021]. We report a case of a left temporal bone giant cell granuloma-like lesion that also shows an FN1-TEK fusion. Close monitoring with MRI images after surgery has showed no recurrence. Case report: a 33-year-old male developed left jaw pain and he was diagnosed with a temporomandibular joint disorder. He felt left ear fullness and 2 years later experienced severe pain and swelling in the left temporal region. Imaging showed an expansile osseous lesion with multi-cystic components involving the left sphenoid bone as well as all portions of the temporal bone including the mastoid, middle ear cavity, and glenoid fossa. Pathology showed a hemorrhagic giant cell lesion that was negative for H3G34W mutation and USP6 rearrangement, suggesting a reparative giant cell granuloma. A subsequent NGS with the Tempus 648 gene panel did not identify somatic or germline mutations, but an additional Tempus RNA fusion test found a FN1-TEK fusion suggesting the possibility of neoplasia. Close monitoring with brain MRI over past 9 months has shown no signs of recurrence. DISCUSSION A recent small series describes a novel entity called calcified chondroid mesenchymal neoplasm that has FN-1 fusions including a FN1-TEK fusion in one case. The case in that series with FIN1-TEK fusion also showed prominent giant cells. It is unclear whether giant cell granuloma-like lesions with FN1-TEK fusion belong in the calcified chondroid mesenchymal neoplasm spectrum or are a separate non-neoplasm entity that shares the same alteration. More studies are warranted.

Aphasic Syndromes in Cerebral Venous and Dural Sinuses Thrombosis—A Review of the Literature

Aphasia is an acquired central disorder of language that affects a person's ability to understand and/or produce spoken and written language, caused by lesions situated usually in the dominant (left) cerebral hemisphere. On one hand aphasia has a prevalence of 25-30% in acute ischemic stroke, especially in arterial infarcts. On the other hand, cerebral venous and dural sinuses thrombosis (CVT) remains a less common and underdiagnosed cause of ischemic stroke (0.5-1% of all strokes). Aphasia has been observed in almost 20% of patients who suffered CVT. The presence of aphasia is considered a negative predictive factor in patients with stroke, severe language disorders corresponding to arduous recovery. Taking into consideration data from the literature, aphasia is also considered a predictive factor for patients with CVT; its absences, together with the absence of worsening after admission, are determinants of complete recovery after CVT. This review has as the principal role of gathering current information from the literature (PubMed database 2012-2022) regarding the clinical features of aphasic syndromes and its incidence in patients with CVT. The main conclusion of this review was that aphasic syndromes are not usually the consequence of isolated thrombosis of dural sinuses or cerebral veins thrombosis. The most frequent form of CVT that determines aphasia is represented by the left transverse sinus thrombosis associated with a posterior left temporal lesion (due to left temporal cortical veins thrombosis), followed by the superior sagittal sinus thrombosis associated with a left frontal lesion (due to left frontal cortical veins thrombosis). Only a few cases are presenting isolated cortical veins thrombosis and left thalamus lesions due to deep cerebral vein thrombosis. We also concluded that the most important demographic factor was the gender of the patients, women being more affected than men, due to their postpartum condition.

Rhino-Orbital-Cerebral Mucormycosis: A Rare Complication of Uncontrolled Diabetes

Introduction Fungal infection of the central nervous system has become more common over the past two decades. It is frequently diagnosed in patients with underlying pathological conditions. We herein report a case of rhino-orbital-cerebral mucormycosis by outlining the clinical presentation, radiological images, histopathological findings, management plan, and its clinical outcome. Case Description. A 47-year-old man, known to have type 2 diabetes mellitus, presented with severe headache involving the left side of the face, numbness along the left V2 trigeminal nerve, ptosis and dryness of the left eye, short-term memory loss, and right hand numbness. He had a social history of being a bee farmer for which he was exposed to bee stings several times in the past. Neuroradiological imaging showed a left temporal ring-enhancing lesion, suggestive of abscess. The patient underwent craniotomy and resection of the lesion. The histopathological evaluation was suggestive of cerebral mucormycosis, fungal sinusitis, and invasive skull base mucormycosis. Conclusion Rhino-orbital-cerebral mucormycosis is a fulminant fungal infection commonly diagnosed in patients with uncontrolled diabetes. Early diagnosis with radiological and histopathological evaluation is required to identify patients at risk of rhino-orbital-cerebral mucormycosis.

64-Year-Old Woman With Aphasia and Troponin Elevation

64-Year-Old Woman With Aphasia and Troponin Elevation

Prosopagnosia in Two Patients Induced Mainly by Left Anterior Temporal Lesion

Prosopagnosia in Two Patients Induced Mainly by Left Anterior Temporal Lesion

Correlation between retinal nerve fibre layer thickness and white matter lesions in Alzheimer's disease.

Early diagnosis in Alzheimer's disease (AD) is crucial in order to implement new therapeutic strategies. The retina is embryologically related to the brain. Thus, the possible usefulness of optical coherence tomography (OCT) in the early detection of AD is currently being studied. Our aim was to study the relationship between retinal nerve fiber layer (RNFL) thickness and AD. We undertook an observational, analytical, cross-sectional study with consecutive sampling of 32 patients with AD or mild cognitive impairment and a group of healthy controls (C). The total number of eyes studied was 64. An ophthalmological and a comprehensive neuropsychological evaluation were performed in all participants. Quantification of white matter lesions and study of atrophy of the hippocampus by cerebral magnetic resonance were also performed. We observed a significant linear trend towards a thinning of RNFL as the degree of cognitive deterioration increased, in the superior and temporal quadrants of the retina. A significant correlation was also noted between the mean thickness of the RNFL of the left temporal quadrant and occipital white matter lesions (r=-0.579, p=0.038). OCT could be a safe, rapid noninvasive tool providing useful biomarkers in the early detection of cognitive deterioration and AD.

BRAF mutation in overlapping form of Erdheim-Chester and Rosai Dorfman diseases: a unique case restricted to the central nervous system

A 48-year-old man with a history of pleural tuberculosis presented in 2019 with paraesthesia of the left hemiface. The clinical examination was consistent with a fifth cranial nerve involvement. A brain MRI revealed three hyper-FLAIR and contrast enhanced lesions in the left cerebellar peduncle (Fig. 1), the left temporal lobe and the left occipital lobe. Perfusion images showed no hyperperfusion, and spectroscopy revealed a tumour profile, with a pick of choline and low NAA. A whole-body CT scan, PET CT scan, spinal MRI, CSF analysis and blood tests were normal, leading to the conclusion of an isolated brain disease. Therefore, a biopsy of the left temporal lesion was performed to differentiate the three main diagnostic hypotheses: infectious (tuberculosis); inflammatory (neurosarcoidosis, neuro-Behcet); tumoral (primary CNS lymphoma) disease.

Nocardia abscessus brain abscess in an immunocompetent host

Background: Nocardia brain abscesses are a rare central nervous system infection with high morbidity and mortality. They typically occur in immunocompromised patients. The most frequent agents involved are Nocardia asteroids complex and Nocardia brasiliensis. Case description: We present the case of a 42-year-old man who was admitted with a 1-week history of headache and incoherent speech, gradually worsened during this period. The patient did not report either fever, chills, weakness or numbness in the limbs. He was a construction worker and lived in a rural environment. He had been recently hospitalized and diagnosed with a solitary pulmonary nodule, still under study in another hospital. The initial finding in CT was an intra-axial, left temporal posterior space-occupying lesion with extensive surrounding oedema, which was presumed to be a metastasis from a possible lung cancer. The patient had a normal neutrophil function test, lymphocyte count and normal immunoglobulin levels. He was negative for human immunodeficiency virus. After admission, the patient underwent a craniotomy with stereotactic biopsy of the lesion. During the surgery, turbid pus was drained and a cerebral abscess was diagnosed. Empiric parenteral antibiotics were started with Ceftriaxone 2 g bid and Metronidazole 500 mg tid. After identifying Nocardia abscessus in the pus culture, the antibiotic regimen was changed to SMX-TMP (15 mg/kg/day of the TMP component) and Meropenem 2 g tid. In the absence of clinical and radiologic improvement, amikacin was added to the treatment, but no surgical re-intervention was performed. During hospitalisation, he also developed a pulmonary invasive aspergillosis, treated with parenteral Voriconazole 4 mg/kg bid. The patient's response to treatment was slow but effective. He was discharged with oral SMX-TMP and Voriconazole therapy. Discussion: Despite several difficulties in diagnosis of a Nocardia infection, there are some characteristics that can suggest the presence of this bacteria. Treatment should be instituted as soon as possible, regarding both surgical and medical approaches. Conclusion: Nocardial brain abscesses are a rare condition that needs to be considered as a differential diagnosis in patients with brain lesions, even in immunocompetent hosts.

Brain Infection from Mycobacterium chimaera: A Case Report

We describe the first case report of pathology-proven brain infection by Mycobacterium chimaera (MC). A 35-year-old male, previously operated in 2010 of aortic valve and ascending aortic replacement, was addressed to our hospital for the acute onset of aphasia preceded by absence. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed multiple left frontal and temporal cortical-subcortical lesions. During hospitalization the patient never presented fever and cerebrospinal fluid (CSF), PCR, FilmArray and blood tests were within normal ranges. Transesophageal echocardiography showed no cardiac abnormalities. A thorax-abdomen CT scan was performed, revealing no extracranial abnormalities, and a whole body PET-CT scan showed a high uptake of brain lesions. Considering clinical results and the suspect of a tumoural lesion, the patient underwent surgery, where a left frontal enhanced nodular lesion was removed. Pathology finally revealed it was an abscess caused by Mycobacterium chimaera. This case confirms that Mycobacterium chimaera infection spread can be very subtle and diagnosis a real challenge, particularly years after surgery. We would like to underline the importance of suspecting an atypical infection source related to a history of cardiothoracic surgery, given a non-specific MR pattern and subtle clinical and laboratory findings.

A radiotherapy refractory brain lesion among breast cancer metastases diagnosed postoperatively as glioblastoma multiforme: A case report

BackgroundBreast cancer is the most common cancer among women. The association between breast cancer and glioblastoma multiforme has not been investigated thoroughly. This case presents a case of glioblastoma multiforme (GBM) which was found concurrently with breast cancer metastases. Case SummaryThe patient is a 53 years old right-handed female with a history of breast cancer, metastatic to bone and liver, who had undergone stereotactic ablative radiotherapy to manage metastases to T10 vertebra, right acetabulum and left hip bone 2 years earlier. Six months prior to the current presentation, the patient was diagnosed with four apparent metastatic lesions to the brain (left cerebellum, right frontal, left parieto-occipital, and left temporal). The patient received Stereotactic Radiation Therapy (SRT). A follow-up MRI 4 months later revealed that all three smaller lesions responded well to SRT except for a mild increase in the size of the larger left temporal lesion with surrounding edema. The patient underwent a craniotomy for resection of the temporal lesion. Pathology revealed that the lesion was glioblastoma multiforme (GBM) rather than being another brain metastatic tumor. ConclusionAlthoughmost brain tumors are metastases, primary brain tumors should be considered a possibility even in the presence of another source of metastases; especially if there is a lesion refractory to treatment.

An Unexpected Operative Finding of Intracerebral Pus in a Case of Multifocal Cerebral Metastases from Small Cell Lung Cancer

We report a case of a 37yr old female whose pre-operative CT and MRI brain revealed multicentric left frontal and temporal lesions which mimicked intracerebral abscess intraoperatively and confirmed on gram stain as moderate growth of white cells. The patient was commenced on prolonged antimicrobial therapy postoperatively, however, histology reported SCLC metastases with lung as primary and patient was eventually commenced on chemotherapy.

Exoscope-Guided (VITOM 3D) Single-Stage Removal of Supratentorial Cavernous Angioma and Hemangioblastoma: 3-Dimensional Operative Video.

This video shows an exoscope-guided single-stage resection with 3-dimensional technology of a supratentorial cavernoma and a supratentorial hemangioblastoma during the same surgical procedure. The patient is a 42-yr-old man with a history of generalized tonico-clonic seizures. Contrast-enhanced magnetic resonance (MR) revealed the presence of a left frontal cavernoma and a left T1 non-enhancing hypointese temporal lesion (hemangioblastoma). The operation was carried out in the lateral position with the sole use of a 3D-exoscope (VITOM-3D, Karl Storz GmbH&Co, Tuttlingen, Germany). The operating room set-up included the surgeons standing at the head of the patients with the operating and navigator screens in the front of them and the exoscope arm entering from the left side. As recently highlighted, the 3D-exoscope carries several advantages: (1) it allows neurosurgeons to operate in a confortable and stable position; (2) it is less space-occupying in comparison to the microscope; (3) the optics and 3D-screen offer an optimal stereoscopic view in comparison to the 2D-exoscope, important for both surgical and training purposes; (4) although sharing with the endoscope, the image quality and confortable surgeon's position, there is no conflict between the surgical instruments and the scope in the surgical field. The adopted strategy enabled a complete resection of both lesions. The postoperative course was uneventful and the patient was seizure-free; the antiepileptic drugs were discontinued 3 mo after surgery. The 3D-exoscope represents a promising surgical tool, which may become part of the neurosurgical armamentarium. Nevertheless, the conceivable capability to improve neurosurgical results will have to be explored. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The patient has consented to the submission of the surgical video for submission to the journal.

Recursive hierarchical embedding in vision is impaired by posterior middle temporal gyrus lesions

The generation of hierarchical structures is central to language, music and complex action. Understanding this capacity and its potential impairments requires mapping its underlying cognitive processes to the respective neuronal underpinnings. In language, left inferior frontal gyrus and left posterior temporal cortex (superior temporal sulcus/middle temporal gyrus) are considered hubs for syntactic processing. However, it is unclear whether these regions support computations specific to language or more generally support analyses of hierarchical structure. Here, we address this issue by investigating hierarchical processing in a non-linguistic task. We test the ability to represent recursive hierarchical embedding in the visual domain by contrasting a recursion task with an iteration task. The recursion task requires participants to correctly identify continuations of a hierarchy generating procedure, while the iteration task applies a serial procedure that does not generate new hierarchical levels. In a lesion-based approach, we asked 44 patients with left hemispheric chronic brain lesion to perform recursion and iteration tasks. We modelled accuracies and response times with a drift diffusion model and for each participant obtained parametric estimates for the velocity of information accumulation (drift rates) and for the amount of information accumulated before a decision (boundary separation). We then used these estimates in lesion-behaviour analyses to investigate how brain lesions affect specific aspects of recursive hierarchical embedding. We found that lesions in the posterior temporal cortex decreased drift rate in recursive hierarchical embedding, suggesting an impaired process of rule extraction from recursive structures. Moreover, lesions in inferior temporal gyrus decreased boundary separation. The latter finding does not survive conservative correction but suggests a shift in the decision criterion. As patients also participated in a grammar comprehension experiment, we performed explorative correlation-analyses and found that visual and linguistic recursive hierarchical embedding accuracies are correlated when the latter is instantiated as sentences with two nested embedding levels. While the roles of the inferior temporal gyrus and posterior temporal cortex in linguistic processes are well established, here we show that posterior temporal cortex lesions slow information accumulation (drift rate) in the visual domain. This suggests that posterior temporal cortex is essential to acquire the (knowledge) representations necessary to parse recursive hierarchical embedding in visual structures, a finding mimicking language acquisition in young children. On the contrary, inferior frontal gyrus lesions seem to affect recursive hierarchical embedding processing by interfering with more general cognitive control (boundary separation). This interesting separation of roles, rooted on a domain-general taxonomy, raises the question of whether such cognitive framing is also applicable to other domains.