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Background The surgical approaches of colloid cysts commonly include endoscopy or open microsurgery. Each approach carries its own challenges, feasibility, and complications. The aim of the current study is to compare endoscopic versus open microsurgical excision of third ventricular colloid cysts. Methods A retrospective cohort study was conducted to compare the surgical outcomes of endoscopic versus open microsurgical (transcortical-transventricular and transcallosal approaches) excision of colloid cyst of the third ventricle at a tertiary-care medical institute. All patients with a neuroradiologic diagnosis of colloid cyst who subsequently underwent surgical management between January 2003 and June 2020 were included. The neurologic outcome was assessed at the last follow-up visit. Results A total of 32 patients with colloid cysts were included in the study. The mean age was 35.8 ± 18.3 years (range, 4–75 years). Female patients slightly outnumbered male patients (n = 17; 53.1%). A total of 21 patients (65.6%) underwent endoscopic resection of the colloid cyst. Complications were encountered in 7 patients (endoscopic, n = 3; microsurgery, n = 4; P = 0.151). Recurrence was identified in 4 patients (endoscopic, n = 3; microsurgery, n = 1; P = 0.673). Most patients improved neurologically on follow-up visits to the clinic (endoscopic, n = 19; microsurgery, n = 9; P = 0.482). Conclusions Both endoscopic and microsurgical approaches provide favorable surgical outcomes in colloid cyst resection. The complication rates between both approaches is statistically insignificant. The optimal surgical approach for colloid cyst resection remains controversial.

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Objectives: To clarify the spectrum of morphological and molecular subtypes of medulloblastoma (MBL), in addition to MYC and MYCN amplification statuses in a cohort of Saudi patients. The latter was correlated with patient outcome. Methods: We conducted a retrospective cohort study of 57 patients with MBL, diagnosed at the central laboratory of King Abdulaziz Medical City in Riyadh, Saudi Arabia, between 2006 and 2019. Molecular analysis for MYC and MYCN amplification was performed for the 19 most recently diagnosed patients. Results: Classic MBL was the most prevalent histologic subtype and MBL with extensive nodularity was the rarest. The non-WNT/non-SHH molecular subgroup was the most common while the WNT-activated was the least common. Among 19 patients analyzed, MYC and MYCN amplifications were discovered in 2 (10.5%) and 1 (5.3%) cases, respectively, using interphase fluorescence in-situ hybridization. The 2 MYC amplified cases belonged to the large cell/anaplastic subtype and had the worst outcomes. Conclusion: The MYC amplification corresponded with poor prognosis, the large cell/anaplastic variant of MBL, and the non-WNT/non-SHH molecular subtype.

Ependymoma is a circumscribed glioma composed of uniform glial cells with bland nuclei in a fibrillary matrix. It is characterized by the presence of perivascular pseudorosettes. Unusual histopathological findings have rarely been reported in ependymomas, 0.5% of all diagnosed cases. Such unusual and exceedingly rare histological findings include osseous or chondroid metaplasia. To the best of our knowledge, only 15 cases of osseocartilaginous ependymomas have been reported in English literature. We report a 3-year-old boy who presented with ataxia, vomiting, and headache for three months. Radiological imaging revealed a posterior fossa lesion. Histopathological examination of the lesion confirmed a posterior fossa ependymoma with chondro-osseous metaplasia. The present case outlines the clinical presentation, histopathological findings, and outcome of chondro-osseous metaplasia in ependymomas. To date, the etiology of chondro-osseous metaplasia in ependymomas remains uncertain. Further research exploring such phenomenon is of paramount importance to explain how these tumors develop.

BACKGROUND: Digital pathology practice is rapidly gaining popularity among practicing anatomic pathologists. Acceptance is higher among the newer generation of pathologists who are willing to adapt to this new diagnostic method due to the advantages offered by whole slide imaging (WSI) compared to traditional light microscopy (TLM). We performed this validation study because we plan to implement the WSI system for diagnostic services. OBJECTIVES: Determine the feasibility of using digital pathology for diagnostic services by assessing the equivalency of WSI and TLM. DESIGN: A laboratory-based cross-sectional study. SETTING: Central laboratory at a tertiary health care center. MATERIALS AND METHODS: Four practicing surgical pathologists participated in this study. Each pathologist blindly reviewed 60 surgical neuropathology cases with a minimum 8-week washout-period between the two diagnostic modalities (WSI vs. TLM). Intraobserver concordance rates between WSI and TLM diagnoses as compared to the original diagnosis were calculated. MAIN OUTCOME MEASURES: Overall intraobserver concordance rates between each diagnostic method (WSI and TLM) and original diagnosis. SAMPLE SIZE: 60 in-house surgical neuropathology cases. RESULTS: The overall intraobserver concordance rate between TLM and original diagnosis was 86.3% (range 76.7%-91.7%) versus 80.8% for WSI (range 68.3%-88.3%). These findings are suggestive of the superiority of TLM, but the Fleiss' Kappa statistic indicated that the two methods are equivalent, despite the low level of the K value. CONCLUSION: WSI is not inferior to the light microscopy and is feasible for primary diagnosis in surgical neuropathology. However, to ensure the best results, only formally trained neuropathologists should handle the digital neuropathology service. LIMITATIONS: Only one diagnostic slide per case rather than the whole set of slides, sample size was relatively small, and there was an insufficient number of participating neuropathologists. CONFLICT OF INTEREST: None.

Highlights • Myositis ossificans of the deltoid muscle is extremely rare. • We present a case with unique presentation and MRI findings. • Our case had no history of trauma or surgery in the area. • Our case had MRI features mimicking myxoma. • Complete excision was curative., Introduction Myositis ossificans of the deltoid muscle is extremely rare. We present a case with unique presentation and MRI findings. Case Report A 21-year-old female presented with a 3-month history of a swelling in lateral aspect of the right arm. There was no history of trauma, injection, or surgery to the area. Examination showed a 3 × 3 cm firm mass in the deltoid muscle. MRI findings were suggestive of myxoma. Surgical excision was done and histopathology showed the classic features of myositis ossificans. There was no recurrence at the final follow-up 7 months later. Discussion Myositis ossificans of the deltoid muscle is very rare with only 6 cases previously reported in the literature. Our case is unique in presentation because it is the first case reported with no history of trauma, Injection, sickness or surgery in the area. We also review the literature for MRI features of Myositis ossificans and show that our case has a unique pattern. Conclusion We report on a rare case of Myositis ossificans of the deltoid muscle and review of the literature for similar cases and MRI features of Myositis ossificans. We show that our case was unique both in presentation and MRI finding.

BACKGROUND: Treatment of glioblastoma (GB), the most common malignant primary brain tumor in adults, can include alkylating chemo-therapeutic agents. Two molecular biomarkers of treatment response are MGMT (O6-methylguanine-DNA methyltransferase) promoter methylation and IDH (isocitrate dehydrogenase) mutations, which prevent repair of tumor cell DNA damage caused by alkylating chemotherapy. The status of MGMT promoter methylation and IDH mutation are associated with longer survival and a better response to chemotherapy. OBJECTIVE: Assess the prognostic value of MGMT methylation status and IDH mutation in adult Saudi glioblastoma patients. DESIGN: Retrospective, comparative survival analysis. SETTING: Tertiary care center. PATIENTS AND METHODS: The status of the MGMT promoter methylation and IDH mutation was assessed in adult patients diagnosed with GB between 2006 and 2019. A PCR-based assay was used to analyze for methylation of the MGMT promoter. A qualitative assay combining PCR clamping and amplification refractory mutation system technology was used to search for any of the 12 most common mutations in IDH1 and IDH2. Differences in survival were compared between those with and without MGMT promoter methylation and IDH mutation and between other subgroups. MAIN OUTCOME MEASURES: Survival of GB patients relative to MGMT promoter methylation and IDH mutation status. SAMPLE SIZE: 146 patients (80 males and 66 females). RESULTS: Of 43 (29.5%) cases tested for MGMT promoter methylation, 14 (32.5%) were positive. Of 65 (44.5%) cases screened for IDH mutation, 6 cases (9.2%) tested positive. The 36-month survival rate was 47% for the MGMT methylated cohort compared to 27% for their unmethylated counterparts. The 18-month survival rate for the IDH-mutant was 75% compared to 48% for their IDH-wildtype counterparts. CONCLUSION: The findings confirm the positive impact of both MGMT promoter methylation and IDH mutation on the overall survival of Saudi GB patients. LIMITATIONS: Single institute study with relatively few tested cases. CONFLICT OF INTEREST: None.

INTRODUCTION Progressive multifocal leukoencephalopathy (PML) is a rare infection of the central nervous system due to the reactivation of the John Cunningham polyomavirus. It is commonly a progressive fatal disease with worldwide distribution. CASE REPORT We describe a rare case of PML, which was misdiagnosed as neuropsychiatric systemic lupus erythematosus (SLE) with a catastrophic outcome due to delay in diagnosis with superadded cyclophosphamide therapy. CONCLUSION There are several lessons taught from our case. Firstly, in patients with autoimmune disorders who are strongly immunosuppressed, the new onset of cognitive impairment and seizures should alert the treating physician to look carefully for PML. Secondly, in cases of SLE where the diagnosis of the cause of cognitive impairment and seizures is not clear, we suggest that immunosuppression should not be intensified until PML has clearly been ruled out. Lastly, multidisciplinary care in patients with suspected neuropsychiatric SLE including a neurologist, an infectious diseases consultant, a neuroradiologist, and a rheumatologist is needed.

Objective/Background: Glioblastoma (GB) is the most common primary malignant brain tumor in adults. Ki-67 is a nonhistone nuclear protein that is expressed by cells entering the mitotic cycle and is associated with the transcription of ribosomal RNA (rRNA). In gliomas, the extent of expression of Ki-67 is roughly proportional to the histologic grade. Over the years, association studies were conducted trying to link the poor outcome in different types of malignant tumors to the Ki-67 proliferative index. This study is designed to investigate the relationship between the proliferation marker, Ki-67, and the overall survival amongst glioblastoma patients diagnosed between 2006 and 2012 at a single institution in Riyadh, Saudi Arabia. Methods: This is a retrospective cohort study which investigated the status of Ki-67 labeling index in glioblastoma patients diagnosed at King Abdulaziz Medical City, Riyadh, Saudi Arabia, between 2006 and 2012. The Kaplan–Meier survival analysis was used to assess the overall survival (OS) and the Mantel–Cox log-rank test was used to compare the survival curves. Multivariate analysis using Cox proportional-hazards model was used to investigate other factors that might influence the overall survival. Results: A total of 44 glioblastoma patients were included in the study. The median age at diagnosis was 56 (1–91) years. The 12-month survival rate for all glioblastoma patients was 48%. The median survival for patients with Ki-67 labeling index of ≤27%, and >27% was 11 months and 14 months, respectively. Conclusion: The difference between the survival curves of patients with Ki-67 labeling index of ≤27%, and Ki-67 of >27% was statistically insignificant (p = .130). Therefore, Ki-67 labeling index alone cannot predict survival in glioblastoma patients. Keywords: GB, Glioblastoma, Ki-67, Labeling index, Saudi Arabia, Survival

Background: Primary spinal glioblastomas are extremely rare neoplasms and account for only 0.2% of glioblastoma cases. Due to the rare incidence of spinal cord glioblastoma in the literature, its natural history/ outcome remains undetermined. The present article describes the clinical presentation, radiological/pathological characteristics, and outcome of the primary spinal cord glioblastoma. Case Description: Two young patients initially presented with paresis that rapidly progressed to paraplegia. Nondermatomal sensory deficits were also noted, mainly affecting the lower limbs. Neuroradiological imaging revealed an extensive intramedullary spinal cord lesion, with no evidence of concurrent intracranial space-occupying lesions. Thoracic laminectomy, followed by tumor debulking and/or biopsy, was performed. The histomorphology was suggestive of glioblastoma, the World Health Organization grade 4 (Isocitrate Dehydrogenase-wild type). They were discharged in stable condition and were started on chemoradiotherapy, with clinicoradiological follow-up. One patient passed away after 9 months of initial presentation. The other patient was alive at 6-month follow-up. Conclusion: Primary spinal glioblastoma is a rare and challenging tumor. Patients commonly present with a progressive paresis, resulting in paraplegia, regardless of the surgical resection extent, and received adjuvant chemotherapy. Therefore, primary spinal cord glioblastoma should be considered in patients reporting a rapid lower limb weakness with neuroradiological evidence of extensive, exophytic intramedullary lesion of the spine. A biopsy-proven histopathological diagnosis is of indisputable importance to establish the final diagnosis and plan treatment options.

Background: Metastatic brain lesions, of thyroid origin, are rare manifestations of differentiated thyroid cancer, with papillary thyroid carcinoma being the most common subtype. Considering the rarity of metastatic follicular thyroid carcinoma to the brain, the present article outlines its clinical presentation, neuroradiological findings, pathological features, and outcome. Case Description: A 52-year-old female presented with a 6-month history of progressive and holocephalic headache. Examination revealed a tracheal deviation to the left side due to an enlarged goiter. Brain CT scan showed a right occipital, slightly hyperdense lesion associated with a 0.4 cm midline shift to the left side. Brain MRI demonstrated a right occipital, avidly-enhancing, extra-axial lesion with disproportionate and extensive vasogenic edema. As the lesion was solitary, the patient underwent craniotomy and tumor resection. Histopathological examination revealed a tumor consistent of small follicles, composed of uniform round nuclei without papillary thyroid carcinoma nuclear features, suggestive of metastatic follicular thyroid carcinoma to the brain. Postoperatively, the patient was neurologically intact. She was discharged in a stable condition with laboratory/ radiological investigations and follow-up at neurosurgery, endocrine, radiotherapy, and thyroid surgery clinics. Conclusion: Follicular thyroid carcinoma may rarely metastasize to the central nervous system. A high index of suspicion is required to identify patients with thyroid cancer who initially present with neurological manifestations. Complete surgical resection of the metastatic brain lesion is safe, feasible and is associated with a prolonged overall survival.

Background: Sellar xanthogranulomas are rare intracranial lesions comprising Case Description: A 43-year-old female, known to have diabetes, hypothyroidism, and polycystic ovarian syndrome, presented with a 2-week history of sudden right-sided facial deviation, periorbital pain, and moderate-intensity headache. The patient also reported amenorrhea not improving with polycystic ovarian syndrome treatment. Neurologic examination showed bilateral visual field defects and impaired visual acuity. Computed tomography scan, without contrast, revealed a hypodense sellar lesion with areas of hyperdensity. Magnetic resonance imaging showed a well-defined sellar lesion, exhibiting high signals on T1-weighted and T2-weighted images. The patient underwent microscopic trans-nasal trans-sphenoidal excision of the lesion. Histological sections of the sellar lesion revealed fibrous connective tissue with chronic inflammatory cells and cholesterol clefts, suggestive of xanthogranuloma. The patient is currently followed up at neurosurgery, endocrinology, and ophthalmology clinics with periodic laboratory/radiological investigations. Conclusion: Sellar xanthogranulomas remain rare intracranial lesions with few cases reported in the literature. Patients mostly present with severe hypopituitarism and visual dysfunction. They show no characteristic radiological features. The diagnosis is confirmed histopathologically, and the prognosis is generally favorable.

We report on a rare association of WNT-activated medulloblastoma with metastasis to the suprasellar region. Medulloblastoma is the commonest brain tumor in children, and the most common pattern of metastatic disease is that of leptomeningeal involvement and spinal metastasis. Historically, medulloblastoma patients were categorized into different risk groups on the basis of age, histology, size of residium after surgery, and metastatic status, but the discovery of at least 4 molecular subgroups has changed the way these tumors are now treated. We report a 6-year-old patient who had a rare association of WNT-activated medulloblastoma with suprasellar metastasis and went on to develop hypopituitarism during the course of treatment. He remains alive 1 year after completing treatment.

Dysferlinopathies encompass a group of neuromuscular diseases characterized by the absence of dysferlin in skeletal muscle. It is a genetic disorder caused by a mutation in the dysferlin gene (DYSF) with an autosomal recessive mode of inheritance. In this article, we report a case of Limb-girdle muscular dystrophy type 2B with a rare homozygous duplication c.164dupA, p.(Ile57Hisfs*8) (rs863225020) in DYSF in a Saudi patient. To the best of our knowledge, this is the first case from Saudi Arabia with complete clinical data, pathology findings, radiology findings, and genetic analysis. Although there is no curative treatment for this disease, an accurate diagnosis is important to avoid using steroids and immunosuppressive medications, which are not effective and may have several side effects. Further studies are needed to explore potential therapies for this rare condition.

Tumefactive multiple sclerosis or tumefactive demyelinating lesion (TDL) is one of the rare variants of multiple sclerosis (MS) posing a diagnostic challenge and a therapeutic enigma since it is difficult to distinguish from a true central nervous system (CNS) neoplasm or other CNS lesions on magnetic resonance imaging (MRI). The prevalence of TDL is estimated to be 1-3/1000 cases of MS with an annual incidence of 0.3/100,000. This could be an underestimate due to unavailability of a global MS registry and under-reporting of this condition. TDL may occur at any age with the ages between the 20s and 30s being more frequently affected. The pathogenesis of TDL remains unknown, but some speculations have been made. These include the autoimmune theory based on the close relationship between TDLs and MS, Fingolimod use, Fingolimod cessation, and Natalizumab use. The clinical presentation of patients with TDL is variable and atypical for demyelinating disease due to the differences in size and location of the lesion. In this article, we aim to explore TDL comprehensively and provide an evidence-based approach for diagnosis and treatment. This will result in recommendations that may improve the diagnostic accuracy and treatment outcomes. Detailed history, physical examination, and several MRI imaging can spare patients the need for a brain biopsy. Treatment of acute lesions includes corticosteroids and plasma exchange therapy. When a diagnosis of relapsing-remitting MS is fulfilled, conventional first line MS disease modifying therapy should be used. Available recently published data suggests that Fingolimod should not be used in TDL patients, mainly due to the possibility of more than just a chance association between TDLs and initiation of Fingolimod. The use of several new MS disease modifying therapy for the management of TDL remains to be studied. Further well-conducted research including multi-center trials is needed to explain several ambiguous aspects related to the etiology and management of TDL.

We read with interest the study by Moller and colleagues.1 The isolation and relative homogeneity of the Saudi population enhance the potential to discover founder mutations, while its high rates of consanguinity enhances homozygosity even for typically dominant disease genes.2 3 We have previously explored the contribution of Lynch syndrome (LS) to colorectal cancer (CRC) based on ~800 Saudi patients.4 We have since expanded our cohort to 1207 CRC patients. Of the 112 mismatch repair deficient (dMMR) cases, MMR gene mutations were identified in 26 cases and these varied in their cancer risk by age 50 years (figure 1). Three founder mutations were observed, accounting for 42.3% (n=11) of LS cases, and none is listed in gnomAD. The PMS2 :c.1376C>G;p.S459X variant was the most commonly encountered LS variant (n=6), and we calculated its minor allele frequency at 0.0001. ​ Importantly, we were able to identify a homozygous individual for PMS2 :c.1376C>G;p.S459X through a large scale whole-exome sequencing (WES) study.2 This individual presented at age 8 years with haematochezia and a typical picture of familial adenomatous …

Fibrous Dysplasia is a benign fibro-osseous lesion occurring throughout the skeletal system with a predilection for craniofacial bones, long bones, and ribs. Fibrous dysplasia develops during bone formation and growth with a variable natural evolution. It is considered a genetic nonheritable disease resulting from missense mutations that occur postzygotically in the GNAS1 gene. This mutation leads to a focal congenital failure of proper bone formation and arrest at the woven bone stage. In turn, this leads to a decreased mechanical strength, causing bone pain, pathological fractures, and skeletal deformities. Besides clinical examination, fibrous dysplasia is diagnosed based on the results of radiographic imaging and the microscopic histopathological findings. On CT scan, fibrous dysplasia shows the characteristic "Ground-glass" appearance with well-defined borders. On MRI, fibrous dysplasia has a low signal intensity on T1-weighted MRI and variable signal intensity on T2-weighted MRI. We hereby report a case of an unusual presentation of fibrous dysplasia in a 67-year-old female presenting to the emergency department with generalized malaise and lower limb pain. Fibrous dysplasia may present in the elderly population and can be difficult to differentiate from other malignant and benign lesions affecting the skeletal system.

The simultaneous development of two or more primary central nervous system (CNS) tumors of different cell types represents 0.9% of all diagnosed CNS tumors. To the best of our knowledge, the simultaneous occurrence of glioblastoma and pituitary adenomas has been reported four times in the English literature, with only two cases harboring prolactinoma and glioblastoma. We report a case of a 42-year-old male who was diagnosed with a sporadic co-occurrence of glioblastoma and a prolactin-secreting pituitary adenoma (prolactinoma). This case report discusses the clinical presentation, radiological/histopathological features, and outcome as well as reviewing the pertinent medical literature. Glioblastoma and a prolactin-secreting adenoma may be detected within the same patient. Further studies are required to delineate the tumorigenesis of the development and co-occurrence of multiple intracranial tumors.

Background Although meningiomas are considered benign, encapsulated brain tumors, their distinct intracranial location can lead to devastating complications. Although a highly vascularized tumor, a rarely reported complication of meningioma is hemorrhage. To the best of our knowledge, only 19 cases of meningioma presenting with a subdural hematoma have been reported. Case Description We have outlined the clinical presentation, radiological findings, and outcomes of 2 female patients with a diagnosis of a spontaneous subdural hematoma associated with meningioma. The coagulation profile was within normal limits for both patients. The postoperative histopathologic examination results showed an angiomatous/microcystic subtype of meningioma (patient 1) and meningothelial meningioma (patient 2). Both patients underwent right frontal craniotomy, resection of the dural-based tumor, and evacuation of the subdural hematoma. Conclusions We comprehensively reviewed the pertinent data for meningiomas presenting as subdural hematomas. The mechanism of hemorrhage in meningiomas remains unclear. Therefore, further studies are required to investigate the possible mechanisms of bleeding in such tumors.

Acute disseminated encephalomyelitis (ADEM), is an immune-mediated demyelinating disease of the central nervous system that commonly affects children and young adults of both sexes. Hyperacute variants of ADEM represent 2% of cases and are associated with rapid progression of symptoms, malignant brain edema, and high mortality rates. We report a case of a young woman presenting with a hyperacute storming course of few days who was managed with pulse steroid therapy and emergency craniectomy with an excellent outcome. We believe that our patient's acute clinical deterioration and findings on neuroimaging warranted prompt neurosurgery. Although treatment with immunomodulatory medications was commenced, the severity of her condition indicated that only surgical intervention was likely to be lifesaving. We recommend immediate neurosurgical consultation to consider prompt decompressive craniectomy in hyperacute variants with significant brain swelling. Multidisciplinary care including neurologist, neuroradiologist, neurosurgeon, neuropathologist, and neurointensivist is the only way to achieve success and improve survival in patients presenting with hyperacute ADEM.

Background When investigating patients with a suspected neuromuscular disorder, a muscle biopsy is considered an instrumental tool to reach a definitive diagnosis. There is a paucity of publications that assess the diagnostic utilization and yield of muscle biopsies. We intend to present our experience in this regard over an extended period of more than three decades. Methods This is an observational retrospective cohort study in which we collected pathology reports for muscle biopsies diagnosed at our reference lab between 1986 and 2017. Results We identified a total of 461 cases of muscle biopsy performed, which fulfilled the inclusion criteria. Pediatric cases defined as ≤14 years of age constituted a significant proportion of cases (n = 275, 60%). Normal biopsies were reported in 27% of cases (n = 124), and in 4%, the biopsies were non-diagnostic. The most common pathologies reported were non-specific myopathy (n = 72, 16%), dystrophy (n = 71, 15%), and neurogenic disorders (n = 60, 13%). Conclusion In conclusion, the muscle biopsy will continue to play a crucial role, as a gold standard or as a complementary investigation, in the diagnosis of certain neuromuscular disorders. Increasing the yield and accuracy of muscle pathology should be the main concern and priority to neuropathologists reporting muscle biopsies. In addition, utilizing next-generation sequencing and other molecular techniques have changed the location of muscle biopsy in the algorithm of the diagnosis of neuromuscular disorders. This paper is an urgent call to establish the Saudi Neuropathology Society and the muscle pathology and neuromuscular disorders registry.

A 24-year-old Saudi man presented with progressive lower-back pain for 3 months followed by lower-limb weakness, numbness, and urinary retention. Cerebrospinal fluid examination revealed high-protein, elevated white blood cell count with lymphocyte predominance. MRI scan of the spine demonstrated heterogeneously enhancing longitudinal spinal cord lesion from T6 through T9. FDG-PET/CT demonstrated prominently hypermetabolic lesion in the spinal cord. He had laminectomy and spinal cord (intramedullary) biopsy. Pathology revealed Schistosoma mansoni ova.

Inflammatory myofibroblastic tumor (IMT) is a genetically heterogenous tumor of the viscera and soft tissues, with multiple molecular features having been demonstrated in this tumor type. About 50% of cases harbor an anaplastic lymphoma kinase (ALK) gene rearrangement, and recent studies have described novel fusions involving the ROS1 and PDGFRβ genes in a subset of ALK-negative cases. However, the molecular features of the remaining subset of cases are not yet defined. We report a case of a large, highly aggressive IMT of the lung in a 17-year-old girl. This case was molecularly characterized through whole-genome and transcriptome sequencing. Subsequently, we investigated a cohort of 15 ALK-negative IMTs of various anatomic sites. All cases were screened using fluorescence in situ hybridization (FISH) for rearrangement of the ETV6 locus and with reverse transcription polymerase chain reaction (RT-PCR) for the ETV6-NTRK3 fusion transcript. Whole-genome and transcriptome sequencing revealed an ETV6-NTRK3 fusion transcript in our index case. This was confirmed by FISH studies for ETV6 gene rearrangement, as well as by RT-PCR. In addition, 2 additional cases in our cohort demonstrated ETV6 rearrangement by FISH. The presence of ETV6-NTRK3 fusion transcript was demonstrated by RT-PCR in one of these additional cases. In summary, we demonstrate the expression of the ETV6-NTRK3 fusion oncogene in a small subset of IMTs, lending further support to the role of oncogenic tyrosine kinases in the pathophysiology of this tumor type. Our data also further expand the growing spectrum of tumor types expressing the ETV6-NTRK3 fusion.

Epithelioid and rhabdoid glioblastomas are rare entities that share some overlapping morphologic features, but remain poorly characterized at the immunohistochemical and genetic level. We report 10 examples: 8 epithelioid glioblastomas (E-GBMs) and 2 rhabdoid GBMs (R-GBMs). E-GBMs tended to be superficially located, circumscribed, supratentorial tumors composed of monotonous, discohesive sheets of small rounded cells that mimicked metastatic malignant melanoma. R-GBMs showed tumor with classic rhabdoid features arising as a subpopulation of an otherwise classic GBM, fitting the definition of composite extrarenal rhabdoid tumors. Polyphenotypic immunohistochemical expression and focal loss of INI-1 protein in the rhabdoid areas of R-GBMs distinguished them from E-GBMs. Monosomy 22 was identified in R-GBMs, but not E-GBMs. Immunostaining for claudin-6, a key component of tight junctions that we have earlier shown to be a positive cytoplasmic immunohistochemical marker for atypical teratoid or rhabdoid tumors (AT/RTs), was also conducted. None of the E-GBMs or R-GBMs showed claudin-6 cytoplasmic expression, including the focal areas in the 2 R-GBMs in which there was loss of INI-1 protein nuclear expression. Thus, in the CNS, claudin-6 expression may be a good discriminator of atypical teratoid or rhabdoid tumors from other CNS rhabdoid or epithelioid neoplasms.

We describe how the combination of imaging and histologic findings was essential in establishing a preoperative diagnosis of an extremely rare malignant granular cell tumor (GrCT) occurring in the lower extremity of a 17-year-old man. Magnetic resonance imaging demonstrated a large infiltrative tumor of heterogeneous intermediate signal intensity on both T1- and T2-weighted sequences. Subsequent computed tomography (CT) and fluorodeoxyglucose positron emission tomography CT scans of the patient revealed distant nodal and skeletal metastases.

Martin Hasselblatt · Inga Nagel · Florian Oyen · Kerstin Bartelheim · Robert B. Russell · Ulrich Schuller · Reimar Junckerstorff · Marc Rosenblum · Ali H. Alassiri · Sabrina Rossi · Irene Schmid · Nicholas G. Gottardo · Helen Toledano · Elisabetta Viscardi · Milagros Balbin · Leora Witkowski · Qianhao Lu · Matthew J. Betts · William D. Foulkes · Reiner Siebert · Michael C. Fruhwald · Reinhard Schneppenheim

Extraneural metastases of ependymoma are very rare, and have been reported in the lungs, lymph nodes, pleura, mediastinum, liver, diaphragmatic muscle, and bone. We describe the radiological findings of pathologically proven lung metastases from an anaplastic ependymoma. The tumor which arose in the posterior fossa was first diagnosed in 2007 when first surgical resection was performed outside our institute. Multiple operations were performed after that due to tumor relapse. Multiple lung nodules were discovered incidentally during a VP shunt survey. Biopsy from the lung nodules displayed identical histomorphology to the primary brain tumor.