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Isocitrate dehydrogenase (IDH) mutant gliomas are associated with a better prognosis in comparison to adult IDH wild-type glioma and glioma-CpG island methylator phenotypes. Although OLIG2 is mainly expressed in oligodendrocytes in normal adult brain, it is expressed in both astrocytomas and oligodendrogliomas. Utilizing the clinical, DNA methylation, and RNA-sequencing data from the Cancer Genome Atlas (TCGA) for lower-grade glioma and glioblastoma cohorts, we explored the association between IDH mutation status and OLIG2 expression on transcription, DNA methylation, and gene target levels. Compared to IDH wild-type gliomas, IDH mutant gliomas showed consistently higher expression of OLIG2 transcripts. OLIG2 overexpression is a good surrogate marker for IDH mutation with an AUC of 0.90. At the DNA methylation level, IDH-mutant gliomas showed hyper- and hypomethylation foci upstream of the OLIG2 transcription start site. Underexpressed OLIG2 target genes in IDH mutant glioma were enriched in cell cycle-related pathways. Thus, the differential expression of OLIG2 between IDH mutant and wild-type gliomas reflects involvement in multiple pathways in tumorigenesis., (Published by Oxford University Press on behalf of American Association of Neuropathologists, Inc. 2022.)

The rate of syphilis in the United States has been increasing steadily in the past decade, but it remains an uncommon diagnosis in tissue biopsies. Most of the pathology literature on hepatic syphilis consists of older series or case reports. This study aimed to systematically characterize the histologic spectrum of hepatic syphilis in a contemporary cohort. Clinicopathologic features of 14 hepatic syphilis cases between 2012 and 2018 were analyzed to characterize the broad spectrum of histologic changes. Thirteen patients were men (age range: 19 to 59 y); 6 had known human immunodeficiency virus, 7 were men known to have sex with men, and no patient had known prior syphilis. Hepatic syphilis was the primary clinical suspicion in only 1 patient. Common symptoms included jaundice, rash, and abdominal pain. Thirteen had elevated transaminases, and 12 had elevated alkaline phosphatase. Pathologic changes were grouped into 5 histologic patterns: biliary-pattern injury (n=5), acute hepatitis (n=4), autoimmune hepatitis-like (n=1), fibroinflammatory mass-forming lesion (n=2), and no particular pattern (n=2). Nearly all showed portal and lobular lymphocytes and plasma cells; 12 had prominent histiocytes/Kupffer cells, 9 had ductular reaction, and 7 had duct inflammation. Occasional focal findings included dropout (n=7), phlebitis (n=7), and loose granulomata (n=5). Treponeme immunohistochemistry was positive in 10 and negative in 4, though treatment was given before biopsy in 3 of those 4. Thirteen patients had rapid plasma reagin testing either before or after biopsy, with 1:64 or higher titer. All patients who received treatment recovered. Hepatic syphilis is rare but likely underrecognized. It exhibits a variety of histologic appearances and therefore should be considered in several hepatic differential diagnoses, especially in men who have sex with men. Kupffer cells, granulomata, and phlebitis may suggest the diagnosis regardless of predominant histologic pattern. Negative treponeme immunohistochemical staining does not exclude the diagnosis, including in untreated patients., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Sarcina species are anaerobic gram-positive cocci rarely seen in the upper gastrointestinal tract and associated with delayed gastric emptying. We present 3 cases of Sarcina infection with varying clinical presentations including the first reported case of Sarcina in a patient with eosinophilic esophagitis. Although the pathogenesis of Sarcina is unclear, awareness of the bacteria is important as they can usually only be detected on histopathologic examination of upper gastrointestinal biopsies. Treatment in symptomatic patients may prevent severe complications such as emphysematous gastritis and gastric perforation.

Saksenaea species are a rare cause of mucormycosis, the majority associated with cutaneous and subcutaneous infections resulting from trauma in both immunocompromised and immunocompetent individuals. Unlike other causative agents of mucormycosis, cerebral infections are exceptionally rare. We describe the first case of isolated cerebral infection by Saksenaea in a 4-year-old previously healthy male child who presented with headaches. He had no past medical history other than an episode of febrile seizures. In addition to raising the awareness of an unusual presentation of infection by Saksenaea, this case highlights the importance of pathologic examination for the prompt diagnosis of mucormycosis as well as the specific fungal identification for treatment as Saksenaea spp. may be more susceptible to posaconazole and less susceptible to amphotericin B compared to more common causes of mucormycosis., (© 2019 Japanese Society of Neuropathology.)

BACKGROUND Gelsolin amyloidosis is a very rare systemic disease presenting with a pathognomonic triad of corneal lattice dystrophy, cutis laxa, and polyneuropathy. The disease is mostly restricted to a Finnish population with known mutations (G654A, G654T) in exon 4 of the gelsolin gene. The mutations lead to errors in protein processing and folding, and ultimately leads to deposition of an amyloidogenic fragment in the extracellular space, causing the symptoms of disease. CASE REPORT We present a case of gelsolin amyloidosis in a male of African descent with an atypical clinical presentation including fevers, skin rash, polyneuropathy, and anemia. Gelsolin amyloidosis was diagnosed based on mass spectrometry of tissue samples. Importantly, a novel mutation in the gelsolin gene (C1375G) in exon 10 was found in this patient. His atypical presentation can possibly be attributed to the presence of a novel mutation in the gelsolin gene as the likely underlying cause of the syndrome. PCR primers were used to amplify the gelsolin gene from genomic DNA. Purified PCR products were then shipped to Eton Biosciences (San Diego, CA) for sequencing. CONCLUSIONS This study carries several important lessons relevant to the practice of medicine. First, the differential diagnosis for multisystem disease presentations should always include amyloidosis. Second, despite what has been uncovered about the molecular biology of disease, there is always more that can be discovered. Finally, further work to verify the link between this mutation and the clinical syndrome is still needed, as are effective treatments for this disease.

We report a case of a 78-year-old male who presented with urinary retention, constipation and an enlarged prostate gland. A transurethral resection of the prostate (TURP) was performed. Pathologic examination revealed a hypercellular-spindled neoplasm with frequent mitoses, nuclear pleomorphism, and multifocal geographic tumoral necrosis. A pathologic diagnosis of gastrointestinal stromal tumor (GIST) was made based on morphologic and immunohistochemical findings, and was later reinforced by molecular study results. This lesion was initially thought to represent a primary prostatic GIST. To the best of our knowledge, there have been only five cases of primary prostatic GISTs. Subsequent imaging studies revealed the mass to be contiguous with the anterior rectal wall, suggesting the possibility of a rectal primary with extension to the prostate gland. The patient was treated with imatinib mesylate, and after twelve months of follow up failed to demonstrate any evidence of progression or metastatic disease. GIST should be considered in cases of prostatic tumors with a spindled or epithelioid morphology, and immunohistochemistry and possible molecular studies are recommended to aid in diagnosis and guide treatment decisions.

Background . Malignant neoplasms arising in Meckel's diverticulum, a vitelline duct remnant, are rare yet well-documented. Case Presentation . A 53-year-old previously healthy female presented with an enlarging midline abdominal wall mass. A computed tomography scan revealed a mass involving the linea alba, bilateral rectus abdominis, and subcutaneous fat. Extensive clinical workup failed to demonstrate other lesions, except local and paratracheal/hilar lymphadenopathy. Histopathologic examination of the resected tumor demonstrated a spectrum of serous neoplasia including serous cystadenoma, papillary serous carcinoma with numerous Psammoma bodies, and a poorly differentiated component. Immunophenotypically, the tumor cells were strongly positive for CK7, CK19, CA19.9, and MUC1 but negative for other lineage markers, findings suggestive of pancreatobiliary type differentiation. The patient died of the disease one year after the initial presentation despite chemotherapy, radiation, and surgery. Conclusion . We present a case of adenocarcinoma arising from the anterior midline abdominal wall, from presumed vitelline duct remnant, with histologic and immunophenotypic features of serous cystadenocarcinoma of pancreatobiliary origin. Though the origin from vitelline duct remnant is difficult to prove in this single case, understanding tumorigenesis of embryonic remnant origin is potentially important to improve the management of cancer of unknown primary., Competing Interests: The authors declare that there is no conflict of interests regarding the publication of this paper.

Juvenile xanthogranulomas (JXG) are uncommon non-Langerhans cell histiocytic proliferations which arise most often in children. While most cases present as solitary cutaneous lesions, occasional cases involve extracutaneous sites. Rare examples of JXGs have been reported involving all levels of the neuroaxis. We present two cases of JXGs involving the nervous system, and review the literature. The first patient was a 14-year-old female with headaches and a mass involving the left trigeminal nerve; pathologic examination showed a JXG. At 11 months follow-up, after administration of systemic chemotherapy, the patient remained stable with residual tumor. The second patient was a 15-year-old female with leg weakness and numbness, who underwent complete surgical resection of a dural JXG. At eight months follow-up, she showed no evidence of tumor, and was able to walk without difficulty. Review of the literature revealed 38 previously published reports of JXGs involving the nervous system. The CNS was involved in the majority (75%) of cases. The clinical characteristics of JXGs arising in the CNS varied significantly from cases in the peripheral nervous system (PNS); CNS tumors occurred in younger patients, more often males, and were more likely to be associated with concurrent cutaneous and extra-nervous systemic lesions. The clinical outcomes were similar for CNS and PNS lesions, with the caveat that all three lethal JXGs occurred in the CNS. The clinical and radiologic presentation of JXGs is nonspecific, thus necessitating biopsy and pathologic examination to arrive at the diagnosis. The pathologic differential diagnosis includes a heterogeneous group of histiocytic proliferations; immunostaining for histiocytic markers CD68, factor XIIIa, and Fascin, and the absence of Birbeck granules and CD1a immunoexpression suggests the diagnosis of JXG. In many cases, total surgical resection is curative. However, some cases will require additional chemotherapy and/or radiotherapy., (© 2012 Japanese Society of Neuropathology.)