Faculty Bibliography

Inflammatory orbital lesions include a broad list of diagnoses, many of them with overlapping clinical and radiographic features. They often present a diagnostic conundrum, even to the most experienced orbital specialist, thus placing considerable weight on surgical biopsy and histopathological analysis. However, histopathological diagnosis is also inherently challenging due to the rarity of these lesions and the overlaps in histologic appearance among distinct disease entities. We herein present the case of an adolescent male with a subacutely progressive orbital mass that generated a significant diagnostic dilemma. Early orbital biopsy was consistent with a benign fibro-inflammatory lesion, but corticosteroid therapy was ineffective in halting disease progression. After an initial substantial surgical debulking, histopathological analysis revealed several key features consistent with IgG4-related disease (IgG4-RD), a systemic fibro-inflammatory process typically accompanied by multifocal tumor-like lesions. Surprisingly, within months, there was clear evidence of clinical and radiographic disease progression despite second-line rituximab treatment, prompting a second surgical debulking. This final specimen displayed distinctive features of Rosai-Dorfman disease (RDD), a systemic inflammatory disease characterized by uncontrolled histiocytic proliferation. Interestingly, certain features of this re-excision specimen were still reminiscent of IgG4-RD, which not only reflects the difficulty in differentiating RDD from IgG4-RD in select cases, but also illustrates that these diagnoses may exist along a spectrum that likely reflects a common underlying pathogenetic mechanism. This case emphasizes the importance of surgical biopsy or resection and histopathological analysis in diagnosing-and, ultimately, treating-rare, systemic inflammatory diseases involving the orbit, and, furthermore, highlights the shared histopathological features between RDD and IgG4-RD.

BACKGROUND:Ventriculoatrial shunts can be afflicted with distal malfunctions due to thrombus formation at the distal tip. Distal tip thrombus formation may occur more commonly in oncologic patients who are predisposed to hypercoagulability. CASE DESCRIPTION/METHODS:A patient who had a ventriculo-atrial shunt placed for leptomeningeal carcinomatosis presented with headaches and confusion and was found to have a partial distal shunt obstruction. Intra-reservoir administration of alteplase resulted in resolution of her symptoms. Nuclear medicine shunt patency test demonstrated restoration of distal flow. CONCLUSIONS:Intra-reservoir administration of alteplase can be a useful non-operative treatment strategy for ventriculo-atrial shunt malfunction. This strategy may be particularly useful in cases with higher peri-operative risk, such as patients with advanced metastatic cancer.

Background/UNASSIGNED:Diagnosis of diffuse intrinsic pontine glioma (DIPG) has relied on imaging studies, since the appearance is pathognomonic, and surgical risk was felt to be high and unlikely to affect therapy. The DIPG Biology and Treatment Study (DIPG-BATS) reported here incorporated a surgical biopsy at presentation and stratified subjects to receive FDA-approved agents chosen on the basis of specific biologic targets. Methods/UNASSIGNED:Subjects were eligible for the trial if the clinical features and imaging appearance of a newly diagnosed tumor were consistent with a DIPG. Surgical biopsies were performed after enrollment and prior to definitive treatment. All subjects were treated with conventional external beam radiotherapy with bevacizumab, and then stratified to receive bevacizumab with erlotinib or temozolomide, both agents, or neither agent, based on O6-methylguanine-DNA methyltransferase status and epidermal growth factor receptor expression. Whole-genome sequencing and RNA sequencing were performed but not used for treatment assignment. Results/UNASSIGNED:Fifty-three patients were enrolled at 23 institutions, and 50 underwent biopsy. The median age was 6.4 years, with 24 male and 29 female subjects. Surgical biopsies were performed with a specified technique and no deaths were attributed to the procedure. Two subjects experienced grade 3 toxicities during the procedure (apnea, n = 1; hypertension, n = 1). One subject experienced a neurologic deficit (left hemiparesis) that did not fully recover. Of the 50 tumors biopsied, 46 provided sufficient tissue to perform the study assays (92%, two-stage exact binomial 90% CI: 83%-97%). Conclusions/UNASSIGNED:Surgical biopsy of DIPGs is technically feasible, associated with acceptable risks, and can provide biologic data that can inform treatment decisions.

INTRODUCTION: Liquid biopsy has the potential to revolutionize diagnosis and management of cancer. In brain tumors, detection of cell free tumor DNA (ctDNA) and circulating tumor cells (CTC) is challenging due to low level of the circulating material. We present a novel workflow for detection and capture of CTCs. METHODS: Peripheral blood was obtained from five pediatric patients with astrocytoma (n=2), ependymoma (n=1), dysembryoplastic neuroepithelial tumor (n=1), and medulloblastoma (n=1) at initial resection (n=3) and relapse (n=2). Samples were enriched using the Clear-Bridge ClearCell FX1 system and the suspension stained with antibodies against CD56 and CD45. Samples were analyzed using Silicon Biosystems DEPArray to capture single and pooled CTCs. CTCs were identified by CD56 positivity, while leukocytes were positive for CD45 and NK cells double-positive for CD56 and CD45. RESULTS: CTCs were identified in all 5 patient samples. The number of CD56-positive cells isolated from each sample ranged from 1 to 25 (mean 9). The CD56-positive cells were on average 11.8 mum in diameter (range 9.0-15.7 mum), and CD45-positive cells were on average 10.8 mum in diameter (range 8.9-15.9 mum). Single CTCs and CTC pools are amenable to molecular analysis after whole genome amplification. CONCLUSION: We report a novel integrated workflow for capturing CTCs in pediatric patients with brain tumors. While rare, CTCs circulate in peripheral blood of patients with brain tumors regardless of their grade and are amenable for molecular analysis. This method has the potential to serve as a non-invasive diagnostic and monitoring method for pediatric brain tumors

Optic gliomas are brain tumors characterized by slow growth, progressive loss of vision, and limited therapeutic options. Optic gliomas contain various amounts of myxoid matrix, which can represent most of the tumor mass. We sought to investigate biological function and protein structure of the myxoid matrix in optic gliomas to identify novel therapeutic targets. We reviewed histological features and clinical imaging properties, analyzed vasculature by immunohistochemistry and electron microscopy, and performed liquid chromatography-mass spectrometry on optic gliomas, which varied in the amount of myxoid matrix. We found that although subtypes of optic gliomas are indistinguishable on imaging, the microvascular network of pilomyxoid astrocytoma, a subtype of optic glioma with abundant myxoid matrix, is characterized by the presence of endothelium-free channels in the myxoid matrix. These tumors show normal perfusion by clinical imaging and lack histological evidence of hemorrhage organization or thrombosis. The myxoid matrix is composed predominantly of the proteoglycan versican and its linking protein, a vertebrate hyaluronan and proteoglycan link protein 1. We propose that pediatric optic gliomas can maintain blood supply without endothelial cells by using invertebrate-like channels, which we termed primitive myxoid vascularization. Enzymatic targeting of the proteoglycan versican/hyaluronan and proteoglycan link protein 1 rich myxoid matrix, which is in direct contact with circulating blood, can provide novel therapeutic avenues for optic gliomas of childhood.