Midline brain hamartomatous lesions in fibrodysplasia ossificans progressiva with ACVR1 mutations.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder characterized by extensive heterotopic ossification of soft tissue structures leading to severe limitations in movement. FOP is caused by a germline mutation in the activating receptor type IA (ACVR1) gene. Worrisome is the fact that up to a third of diffuse intrinsic pontine gliomas (DIPG) also harbor the same point mutation in ACVR1. Radiological reports of central nervous system (CNS) involvement by FOP have described brainstem masses; however, the literature on the histopathology or pathogenesis of these lesions is scant. Here we present detailed neuropathologic findings of a brainstem mass in a patient with FOP and suggest that the tumor is hamartomatous in nature. This report, along with a literature review of radiographic and laboratory data, offers support for the idea that the ACVR1 mutation may incite CNS proliferation, predominantly in the brainstem, but is probably not an oncologic driver. These lesions may be seen at autopsy and are likely noncontributory to death.

Histologic Findings at the Time of Repeat Resection Predicts Survival in Patients with Glioblastoma.

OBJECTIVE: Radiographic worsening in patients with glioblastoma undergoing treatment may be due to tumor recurrence or treatment effect. The overall prognosis of these patients based on histologic findings at the time of repeat resection is not well established. METHODS: Patients with glioblastoma at our institution were identified. Patients who only had 1 surgery were excluded. Demographic and clinical data were recorded. The histologic diagnosis at the time of repeat surgery was recorded as either tumor recurrence or pseudoprogression. For this study, pseudoprogression was defined as absence of tumor histologic features and could show coagulative necrosis, reactive gliosis, and/or inflammatory infiltration. RESULTS: A total of 115 patients were identified, 106 with tumor recurrence and 9 with pseudoprogression. The pseudoprogression group had a greater percentage of patients with O6-methylguanine DNA-methyltransferase (MGMT) methylation (37.7% vs. 66.7%), but these results did not reach statistical significance. The overall median survival was 23.1 months. The overall median survival was 22.0 months in the tumor recurrence group and 33.3 months in the pseudoprogression group (P = 0.0814). The overall median survival from the time of repeat surgery was 8.4 months for the entire cohort, 8.3 months for the tumor recurrence group and 18.4 months for the pseudoprogression group (P = 0.0063). In multivariable analysis, presence of tumor features was predictive of worse overall survival from the time of second surgery (hazards ratio 3.96, 95% confidence interval: 1.30-12.06, P = 0.0156). CONCLUSIONS: In patients with worsening imaging, the absence of tumor on histologic diagnosis is associated with improved survival from the time of second surgery.

Educational Case: Esophageal Carcinoma.

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.1.

What Every Neuropathologist Needs to Know: Neuropathology and the US Legal System.

The legal system of the United States is complex, with nuances that are particular to its many jurisdictions. The neuropathologist may professionally interact with the legal system in both criminal and civil proceedings as either a fact or expert witness, and in rare instances as a defendant. The nature of the legal issue at hand will define the pathologist's role and determine what actions are required or requested. The intersection of neuropathology and the laws governing quality assurance may be less defined as legal statutes vary by state; although, the general principles of privilege, peer review, and confidentiality remain similar. Aside from a forensic pathology fellowship, there is often little in the way of our training to prepare us for our potential roles in the courtroom. This article serves as a review for the neuropathologist's role as a witness, the legal proceedings that you may participate in, and the intersection between quality assurance and law.

Neurofibromatosis: A Review of NF1, NF2, and Schwannomatosis.

The neurofibromatoses are a heterogeneous group of hereditary cancer syndromes that lead to tumors of the central and peripheral nervous systems, as well as other organ systems. By far the most common form is neurofibromatosis 1 (96%), followed by neurofibromatosis 2 (3%), and a more recently recognized, lesser known form, schwannomatosis. The diagnostic criteria, pathogenesis, molecular considerations, and clinical manifestations are discussed in this review article.

CNS intraoperative consultation: a survival guide for non-neuropathologists.

Intraoperative consultations for central nervous system disease may be challenging due to limitations of sample size, lack of familiarity with neurosurgical procedures, or poor access to neuroimaging studies. Despite these challenges, the surgical pathologist is charged with determining if the tissue sample is representative of the pathologic process while ensuring that enough diagnostic tissue has been retained for routine histology, immunohistochemistry, fluorescence in situ hybridization, molecular testing, and in some cases, tissue banking. Here, we present basic methods and a practical approach for CNS intraoperative consultation including critical pre-analytic considerations that promote optimal tissue management.

Primary Hodgkin lymphoma of the central nervous system: two case reports and review of the literature.

CNS involvement by systemic Hodgkin lymphoma (HL) is quite rare, but the disease limited to the CNS is an exceptionally rare entity. The incidence of CNS-HL has been estimated at 0.2-0.5% of cases, but a more recent study has modified that figure to less than 0.02%. Like the conventional form, the diagnosis of primary CNS-HL rests upon distinct morphological and immunohistochemical characteristics, including diagnostic Reed-Sternberg cells, in addition to staging studies demonstrating a lack of disease elsewhere. The paucity of cases in the literature precludes reliable clinical and demographic data, as well as a consensus on treatment and prognosis. We present two cases of primary cerebellar HL, one with 10-year follow-up, and a relevant review of the literature.