Noncoding GGC repeat expansion of various genes leads to oculopharyngodistal myopathy (OPDM), an adult-onset progressive neuromuscular disorder characterized by ophthalmoplegia, pharyngeal dysfunction, and distal limb muscular weakness. Recently, clinical overlap among noncoding GGC repeat-associated neuromuscular diseases, including OPDM, fragile X-associated tremor/ataxia syndrome (FXTAS), and neuronal intranuclear inclusion disease (NIID), has been recognized. Here, we present an autopsy case of OPDM with GIPC1 mutation (OPDM2) in a 56-year-old man. Histopathological studies revealed loss of myelinated fibers in the cerebrum and the presence of neuronal and glial intranuclear inclusions, which are commonly observed in FXTAS and NIID. Numerous intranuclear inclusions in oligodendrocytes were a characteristic feature of our autopsied case. Although GGC repeat expansions in distinct genes produce similar neuropathological findings, such as neuronal and glial intranuclear inclusions, the affected cell populations differ.

Orbital neurofibromas are benign tumors originating from the peripheral nerve sheath, often linked to neurofibromatosis type 1 (NF1) [1], although they account for less than 1% of all orbital tumors [2, 3]. These tumors can cause symptoms such as proptosis, vision impairment, and ocular misalignment [4]. While typically linked to NF1, multiple isolated orbital neurofibromas in the absence of a definitive NF1 diagnosis remain exceedingly rare, warranting clinical attention. A 56-year-old female presented with ptosis and dystopia on the right side. MRI revealed multiple intraorbital and extraconal masses, with the largest being excised via anterior orbitotomy. Histopathological analysis confirmed the diagnosis of neurofibroma. The patient had no cutaneous or systemic signs suggestive of NF1. In adults, multiple orbital tumors should prompt suspicion for neurofibromas, even when NF1 is not confirmed. Furthermore, recurrence is possible, emphasizing the importance of long-term follow-up. This case highlights the diagnostic challenge posed by orbital neurofibromas without NF1 and the need for comprehensive systemic evaluation in such presentations.

Adult-type diffuse gliomas are the most prevalent type of malignant adult brain tumors. Intratumoral heterogeneity can hinder accurate diagnosis and subsequent treatment. This case report documents a tumor with intratumoral heterogeneity, both histologically and by methylation analysis, located within the left cerebral hemisphere of a 29-year-old female. She presented after a witnessed generalized tonic clonic seizure at home. Two years prior she had a witnessed seizure; however, no brain imaging was done at the time. Magnetic resonance imaging (MRI), on this admission, showed a mass lesion in the left frontal operculum with poorly identified margins and right-sided midline shift. Sampling from the left temporal lobe showed an IDH-mutant, ATRX-mutant astrocytoma, which appeared grade 4 in the enhancing anterior portion and grade 2 in the left temporal lobe. Methylation analysis confirmed this heterogeneity. In summary, this is an excellent example of tumor heterogeneity both histologically and by molecular analysis. It is probable, given the clinical history of presentation 2 years prior, that this tumor originated as a low-grade glioma and subsequently evolved.

The Brain Tumor Epidemiology Consortium (BTEC) is an international organization with membership of individuals from the scientific community with interests related to brain tumor epidemiology including surveillance, classification, methodology, etiology, and factors associated with morbidity and mortality. The 2023 annual BTEC meeting entitled "Impact of Environment on Pediatric and Adult Brain Tumors" was held in Lexington, KY, USA on May 22 - 24, 2023. The meeting gathered scientists from the United States, Canada, Australia, and Europe and included four keynote sessions covering genomic, epigenomic, and metabolomic considerations in brain tumor epidemiology, cancer clusters, environmental risk factors, and new approaches to cancer investigation. The meeting also included three abstract sessions and a brainstorming session. A summary of the meeting content is included in this report.

To characterize expression of factors relevant for Ras signaling and developmental factors in a large series of peripheral nerve sheath tumors (PNST) obtained from patients with neurofibromatosis type 1 (NF1). Tissue micro-array technique was applied to study 520 PNST of 385 NF1 patients by immunohistochemistry for mTor, Rho, phosphorylated MEK, Pax7, Sox9, and periaxin expression. PNST comprised cutaneous neurofibroma (CNF) (n=114), diffuse neurofibroma (DNF) (n=109), diffuse plexiform neurofibroma (DPNF) (n=108), plexiform neurofibroma (PNF) (n=110), and malignant PNST (MPNST) (n=22). All proteins examined showed highest expression levels/highest frequency of expression in MPNST. Benign PNF with potential for malignant dedifferentiation expressed mTor, phosphorylated MEK, Sox9, and periaxin significantly higher/more frequently than other benign neurofibroma subtypes. In NF1-associated PNST, expression of proteins involved in Ras-signaling and development is upregulated not only in MPNST, but also in benign PNF with the potential for malignant dedifferentiation. The differences in protein expression may provide clues for understanding the therapeutic effects of substances applied for reduction of PNST in NF1.

Meningiomas are the most common primary intracranial tumors, of which atypical meningiomas account for ~20%. A loss of NF2 has been proven to be an initial step for meningioma development; however, the role of non-NF2 alterations is unknown. Here we report a case of an atypical meningioma with a NF2 splice donor mutation and four recurrences. Using a custom NGS panel, further complex heterogenic molecular alterations were discovered. At first, one subclone of the initial tumor showed an additional PIK3CA variant, most likely of no pathogenic relevance. Then, the first and second recurrences no longer harbored the PIK3CA variant and no tumor heterogeneity was found. The tumor-driving NF2 mutation persisted, however. The latest, third recurrence showed a remarkable genetic heterogeneity with multiple, additional non-NF2 variants and a pathogenic PIKC3A mutation. In detail, one subclone showed a SUFU and two SMARCE1 variants. Another, geographically separate tumor subclone, in contrast, showed several different non-NF2 variants in SMO, PIK3CA and SUFU. Most important, one of the newly acquired PIK3CA alterations in the kinase domain (L1006F) is likely to be an additional tumor-driving mutation, which activates the PI3K-AKT-mTOR pathway. The reported genetic heterogeneity in meningiomas has been addressed in only a few studies. Although some of the detected variants in our case are expected to have biochemical consequences, these consequences are usually not likely to promote tumor development, when taking into account the suggested role of the altered proteins in tumorigenic pathways. However, the occurrence of a single oncogenic missense mutation in a subclone of the third recurrence may indicate a clonal change towards enhanced aggressiveness. Taken together, our case supports the need to perform in-depth studies to clarify the role of non-NF2 mutations for meningioma growth and development.