Aditya Raghunathan

Teflon granulomas mimicking cerebellopontine angle tumors following microvascular decompression.

To report two patients with a history of microvascular decompression (MVD) for hemifacial spasm who presented with Teflon granulomas (TG) mimicking cerebellopontine angle (CPA) tumors and to perform a systematic review of the English‐language literature.

Clinically significant intratumoral hemorrhage in patients with vestibular schwannoma

The frequency of intratumoral hemorrhage (ITH) in vestibular schwannoma (VS) remains undefined.

Subependymal giant cell astrocytoma-like astrocytoma: a neoplasm with a distinct phenotype and frequent neurofibromatosis type-1-association

Neurofibromatosis type-1 is a familial genetic syndrome associated with a predisposition to develop peripheral and central nervous system neoplasms. We have previously reported on a subset of gliomas developing in these patients with morphologic features resembling subependymal giant cell astrocytoma, but the molecular features of these tumors remain undefined. A total of 14 tumors were studied and all available slides were reviewed. Immunohistochemical stains and telomere-specific FISH were performed on all cases. In addition, next-generation sequencing was performed on 11 cases using a platform targeting 644 cancer-related genes. The average age at diagnosis was 28 years (range: 4–60, 9F/5M). All tumors involved the supratentorial compartment. Tumors were predominantly low grade (n = 12), with two high-grade tumors, and displayed consistent expression of glial markers. Next-generation sequencing demonstrated inactivating NF1 mutations in 10 (of 11) cases. Concurrent TSC2 and RPTOR mutations were present in two cases (1 sporadic and 1 neurofibromatosis type-1-associated). Interestingly, alternative lengthening of telomeres was present in 4 (of 14) (29%) cases. However, an ATRX mutation associated with aberrant nuclear ATRX expression was identified in only one (of four) cases with alternative lenghtening of telomeres. Gene variants in the DNA helicase RECQL4 (n = 2) and components of the Fanconi anemia complementation group (FANCD2, FANCF, FANCG) (n = 1) were identified in two alternative lenghtening of telomere-positive/ATRX-intact cases. Other variants involved genes related to NOTCH signaling, DNA maintenance/repair pathways, and epigenetic modulators. There were no mutations identified in DAXX, PTEN, PIK3C genes, TP53, H3F3A, HIST1H3B, or in canonical hotspots of IDH1, IDH2, or BRAF. A subset of subependymal giant cell astrocytoma-like astrocytomas are alternative lenghtening of telomere-positive and occur in the absence of ATRX alterations, thereby suggesting mutations in other DNA repair/maintenance genes may also facilitate alternative lenghtening of telomeres. These findings suggest that subependymal giant cell astrocytoma-like astrocytoma represents a biologically distinct group that merits further investigation.

Temporal Lobe Gliosarcoma After Gamma Knife Radiosurgery for Vestibular Schwannoma.

Objective: Secondary tumorigenesis after exposure to ionizing radiation is a well-described phenomenon. The probability of developing a malignancy after stereotactic radiosurgery (SRS) is theoretically less than conventional external beam radiation therapy; however, the exact risk remains unknown. Such information is important for patient counseling when considering treatment of benign conditions such as vestibular schwannoma (VS). The objective of the current report is to describe a case of a temporal lobe gliosarcoma developing 3 years after radiosurgical treatment of a sporadic VS. Setting: Tertiary academic referral center. Patient: A 54-year-old man was diagnosed with a left-sided 1.6 cm cerebellopontine angle mass, consistent with VS. After reviewing treatment options, the patient proceeded with radiosurgery, and a tumor volume of 2.4 cm3 was treated with a marginal dose of 12.5 Gy prescribed to the 50% isodose line. Results: Serial magnetic resonance imaging (MRI) revealed good treatment response, demonstrated by central necrosis and tumor shrinkage. However, 3 years after treatment, the patient presented to the emergency department for a month long history of progressive word finding difficulties. Imaging revealed a 5 cm temporal lobe mass consistent with a high-grade glial neoplasm. He subsequently underwent stereotactic resection and final pathology confirmed World Health Organization Grade IV gliosarcoma. Conclusion: De novo malignancy after radiosurgery for VS is rare. We present only the second case of a gliosarcoma arising within the low-dose radiation field of the radiosurgery treatment plan. Some of the challenges of establishing causality between radiation treatment and secondary tumor development are discussed. The reporting of malignancy after radiation therapy, and even microsurgery, warrants continued vigilance.

Unique cause of right hemispheric syndrome: Embolism of myocardium after open septal myectomy

We present a novel case of acute ischemic stroke in the postoperative setting of open septal myectomy. A 24-year-old woman developed acute left hemiparesis and rightward eye deviation the morning after surgery. She underwent emergent endovascular stoke therapy by mechanical embolectomy with successful retrieval of a fragment of myocardium that was obstructing the right middle cerebral artery. To our knowledge there has been no previous case described of a myocardial fragment causing a proximal intracranial artery occlusion with resulting ischemia and infarction.

Low-Grade Malignant Peripheral Nerve Sheath Tumor Mimicking Schwannoma: Role and Importance of Trimethylated H3K27M Staining

BACKGROUND It is important to differentiate low-grade malignant peripheral nerve sheath tumors (MPNSTs) from benign nerve sheath tumors as MPNSTs may require a more aggressive treatment strategy during and after initial resection. Loss of expression of the trimethyl histone H3 at the Lys27 position (H3K27-me3) has recently been described in MPNSTs and may help distinguish this tumor from pathologic mimics. METHODS A 43-year-old woman presented with symptoms of radiculopathy and a history of pelvic radiation for cervical cancer 7 years prior. Imaging and surgical pathology were initially consistent with an L5 schwannoma including spindle morphology without mitoses and retained S100 expression. After an aggressive recurrence 11 months later, pathology was consistent with high-grade MPNST including heightened mitotic activity and loss of S100 expression. RESULTS After the identification of MPNST, H3K27M me3 immunostaining was applied to both the initial and recurrent pathologic specimens. The initial specimen demonstrated patchy loss of H3K27M me3 expression, more consistent with low-grade MPNST than schwannoma. CONCLUSION This case highlights the role of H3K27M me3 immunostaining to help differentiate MPNSTs that may mimic more benign nerve sheath tumors, especially in patients who have a history of radiation to the region in question.

Supratentorial CAPNON associated with WHO grade II meningioma: A case report: CAPNON with atypical meningioma

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare benign tumor of uncertain etiology, arising in the craniospinal axis. CAPNON typically arises in isolation, with only two prior reports of a concurrent second neoplasm. Here, we report the case of a male 17‐year‐old who presented with new‐onset seizures. MRIs revealed a 2 cm extra‐axial solid‐cystic mass, arising at the left temporo‐occipital junction and abutting the dura with marked surrounding parenchymal vasogenic edema. The solid components demonstrated dense calcification and avid enhancement. Gross total surgical resection was performed. Histopathological examination revealed central regions showing characteristic features of CAPNON. Toward the periphery, the CAPNON was intimately associated with and sharply demarcated from a meningioma, which showed up to five mitoses per 10 high‐power fields and had invasion into the adjacent brain parenchyma, warranting a WHO grade II designation. This is the first report of CAPNON arising in association with a meningioma. The coexistence of these two tumors raises the possibility of a reactive/dysplastic etiology for CAPNON.

Sellar Region Atypical Teratoid/Rhabdoid Tumors in Adults: Clinicopathological Characterization of Five Cases and Review of the Literature

Atypical teratoid/rhabdoid tumors (AT/RTs) are highly malignant CNS neoplasms that typically occur in children <2 years of age. These are characterized by high-grade histologic features and mutations of the INI1/SMARCB1 gene readily detected by loss of expression by immunohistochemistry. Among adults, the majority of AT/RTs occurs in the cerebral hemispheres. A small number of adult AT/RTs involving the sellar and suprasellar region reported in the literature suggest a distinct clinical course for this group. Here, we describe detailed clinical and genetic characterization of 5 adult patients with AT/RTs involving the sellar and suprasellar region, and provide a review of the available clinical and genetic features of 22 previously reported cases in order to help increase our understanding of this unusual entity.

Posterior interosseous nerve intraneural ganglion cyst from the scapholunate joint

To the editor: During the course of a routine cadaveric dissection of the wrist, an intraneural ganglion cyst was incidentally identifiedatauniquesite.Theposterior interosseousnerve (PIN) and artery were identified with loupe magnification in the floor of the 4th extensor compartment overlying the distal interosseous membrane. Just distal to the point of arborization at the level of the radiocarpal joint, an intraneural ganglion cyst was noted within one of the branches of the PIN (Figure 1A). This branch, along with the grossly visible cyst, was carefully dissected through the dorsal wrist capsule. The intraneural cyst originated from the scapholunate joint and extended through a fenestration in the scapholunate ligament (Fig. 1B–D). It propagated proximally for approximately 2 cm. A pseudocyst with adjacent nerve fascicles was confirmed histologically, and was traced to the level of the joint in serial sections (Fig. 2). This rare anatomic finding has broad clinical implications. A posterior interosseous intraneural ganglion cyst has not been reported at thewrist (Desy et al., 2017). The PIN intraneural cyst described herein communicated with the scapholunate joint by an articular branch. The scapholunate joint/ligament is the most common site for extraneural ganglion cysts at thewrist. Extraneural cysts in this location arise from non-neural pedicles; some have thought that they can cause occult dorsal wrist pain because of the consistent proximity of the ganglion cyst and the PIN (Dellon and Seif, 1978; Steinberg and Kleinman, 1999). Our group has put forth a unifying articular theory to explain the formation and propagation of intraneural and extraneural ganglion cysts (Spinner et al., 2009). Mounting anatomic and clinical evidence supports this theory (Spinner et al., 2011). Intraneural and extraneural ganglion cysts form from synovial surfaces. Intraneural cysts originate from a synovial joint, egress through a capsular rent and dissect along an articular branch typically extending to the parent nerve; extraneural cysts would egress separate from the nerve. Bothmay present with findings of neuropathy, the former by intrinsic, and the latter by extrinsic compression. The shape and dimensions of these cysts would obey basic principles of fluid dynamics such as the path of least resistance and pressure fluxes. A posterior interosseous intraneural cyst has been described in one case in the elbow region (Hashizume et al., 1995); despite its not being described as having a joint connection by the original authors, our group’s reinterpretation of the published imaging supported an elbow joint connection (Wang et al., 2009). This is the third known example of a joint-related intraneural ganglion cyst found in a cadaver (Spinner and Wang, 2016); the others being a deep ulnar nerve cyst connecting to a carpal bone and a tibial nerve cyst connecting to the knee joint. This specimen extends (and further unifies) our understanding of the pathogenesis of intraneural and extraneural ganglion cysts at the wrist and elsewhere.

A case of epidural glioblastoma metastasis presenting with a cervical myelopathy, torticollis, and L’hermitte’s phenomenon

Extraneural glioblastoma metastases are exceedingly rare, though previously described in the literature. Activating mutations in the BRAF kinase gene (V600E) are present in a minority of glioblastoma patients. Here, we describe a case of systemic metastases of a clonal subpopulation of BRAF V600E mutated glioblastoma in a patient previously treated with surgery, radiation, temozolomide and bevacizumab. The patient presented with a subacute cervical myelopathy during adjuvant treatment. He underwent emergent surgical decompression of an epidural spine metastasis. Analysis of the metastatic tumor demonstrated clonal expansion of a BRAF V600E subpopulation. Though rare, systemic metastasis of glioblastoma should be considered in patients presenting with subacute complaints in line with a mass lesion.