Assessment of H3K27me3 immunohistochemistry and combination of NF1 and p16 deletions by fluorescence in situ hybridization in the differential diagnosis of malignant peripheral nerve sheath tumor and its histological mimics

Clinicopathological differences between classical schwannomas and cellular schwannomas in the retroperitoneum

This study aimed to compare clinical and pathological features of retroperitoneal classical schwannomas and cellular schwannomas. A total of 64 cases of retroperitoneal classical schwannoma and 48 cases of cellular schwannoma were studied. Histopathological analysis was performed using hematoxylin and eosin staining and immunohistochemistry. Retroperitoneal cellular schwannomas exhibited 100% (48/48) and 75% (36/48) positive expression for glial fibrillary acidic protein (GFAP) and cytokeratins (CK), respectively. Classical schwannomas showed rates of 6.25% (4/64) and 15.63% (10/64), respectively (P < .05). In classic schwannomas, 85.9% (55/64) showed a reticular pattern of positive anti-CD34 staining around tumor margins and subcapsular areas vs 52.1% (25/48) in cellular schwannomas (P < .05). Cellular schwannomas exhibited more mitotic figures than classical schwannoma (P < .05). The recurrence rate of cellular schwannomas was 10.42% (5/48), while that of classical schwannomas was 1.56% (1/64) (P < .05). Retroperitoneal cellular schwannomas commonly express GFAP and CK compared to classical schwannomas, suggesting that cellular schwannoma may originate from unmyelinated Schwann cells, while classical schwannoma may originate from myelinated Schwann cells. Anti-CD34 staining patterns may be used to distinguish between the 2 types. Retroperitoneal cellular schwannomas also show higher mitotic activity and are more prone to recurrence.

H3K27me3 Loss in Central Nervous System Tumors: Diagnostic, Prognostic, and Therapeutic Implications

Central nervous system (CNS) tumors represent a formidable clinical challenge due to their molecular complexity and varied prognostic outcomes. This review delves into the pivotal role of the epigenetic marker H3K27me3 in the development and treatment of CNS tumors. H3K27me3, specifically the trimethylation of lysine 27 on the histone H3 protein, plays a crucial role in regulating gene expression and maintaining chromatin architecture (e.g., in X-chromosome inactivation). Notably, a reduction in H3K27me3 levels, frequently tied to mutations in the H3 gene family such as H3F3A and HIST1H3B, is evident in diverse brain tumor variants, including the diffuse midline glioma characterized by the H3K27M mutation and certain pediatric high-grade gliomas. The loss of H3K27me3 has been linked to more aggressive behavior in meningiomas, with the trimethylation loss associated with significantly shorter recurrence-free survival (RFS) among grade 2 meningiomas, albeit not within grade 1 tumors. Pediatric posterior fossa ependymomas characterized by a lowered H3K27me3 and DNA hypomethylation exhibit poor prognosis, underscoring the prognostic significance of these epigenetic alterations in CNS tumors. Comprehending the role of H3K27me3 in CNS tumors is vital for advancing diagnostic tools and therapeutic interventions, with the goal of enhancing patient outcomes and quality of life. This review underscores the importance of ongoing investigations into H3K27me to refine and optimize management strategies for CNS tumors, paving the way for improved personalized medicine practices in oncology.

Current state of spinal nerve sheath tumor management and future advances

Nerve sheath tumors are the most common tumors of the spine after meningiomas. They include schwannomas, neurofibroma, and malignant peripheral nerve sheath tumors. These can arise sporadically or in association with tumor predisposition syndromes, including neurofibromatosis type 1, neurofibromatosis type 2, and schwannomatosis. Though surgery is the traditional mainstay of treatment for these tumors, the discovery of the genetic and molecular basis of these diseases in recent decades has prompted investigation into targeted therapies. Here, we give a clinical overview of spinal nerve sheath tumors, their imaging features, current management practices, and explore ongoing advances in systemic therapies.

Contemporary Approach to Neurofibromatosis Type 1-Associated Malignant Peripheral Nerve Sheath Tumors

Most malignant peripheral nerve sheath tumors (MPNSTs) are clinically aggressive high-grade sarcomas, arising in individuals with neurofibromatosis type 1 (NF1) at a significantly elevated estimated lifetime frequency of 8%-13%. In the setting of NF1, MPNSTs arise from malignant transformation of benign plexiform neurofibroma and borderline atypical neurofibromas. Composed of neoplastic cells from the Schwannian lineage, these cancers recur in approximately 50% of individuals, and most patients die within five years of diagnosis, despite surgical resection, radiation, and chemotherapy. Treatment for metastatic disease is limited to cytotoxic chemotherapy and investigational clinical trials. In this article, we review the pathophysiology of this aggressive cancer and current approaches to surveillance and treatment.

Neurogenic tumours of the posterior mediastinum and differential diagnosis considerations

The mediastinal compartment harbours vital organs and structures, including the heart, great vessels, major airways, and thymus. These structures are embedded in and associated with soft-tissue elements consisting of adipose and fibro-collagenous tissue in which soft-tissue tumours may develop. A detailed inventory of soft-tissue tumours that may be encountered in the mediastinum based on the WHO 2013 classification was published in 2015. In addition, several comprehensive reviews on mediastinal soft-tissue pathology are available, including reviews focusing specifically on a single tumour type. This review will focus on primary neurogenic and spindle cell tumours of the somatic soft tissue of the posterior mediastinum and provide a discussion of the pertinent differential diagnoses.

Magnetic resonance imaging analysis of embryonal rhabdomyosarcoma of the prostate

BACKGROUND

Rhabdomyosarcoma (RMS) is a highly malignant tumor that originates from myogenic progenitor cells.

OBJECTIVE

To investigate the magnetic resonance imaging (MRI) characteristics of prostate embryonal rhabdomyosarcoma (ERMS).

METHODS

We retrospectively analyzed the clinical and MRI imaging data of 9 cases of prostate ERMS that were confirmed pathologically. The patients were aged between 14∼49 years with a median age of 27 years, and they all underwent MRI, diffusion-weighted imaging (DWI), and dynamic contrast-enhanced MRI (DCE-MRI).

RESULTS

The MRI scan of the lesions showed an irregular shape, mixed signals, uneven equal/long T1 signal and an equal/long T2 signal, cystic necrosis in 9 cases and hemorrhage in 6 cases; DWI and ADC images showed a mixed high/low signal, and the tumor parenchyma showed ADC low signal, with an average ADC value of 0.666 × 10-3 mm2/s. There were 5 cases of DCE-MRI TIC type II and 4 cases of DCE-MRI TIC type I. The average value of Tpeak was 120 s and the average value of MCER was 172.3%. After the enhancement, the signal of tumor enhancement was uneven, and showed patchy and reticular enhancement, however, the cyst degeneration, necrosis area, and hemorrhage focus were not enhanced. There were 3 cases with multiple pelvic lymph nodes and 1 case with multiple bone metastases.

CONCLUSION

The MRI manifestations of prostate ERMS have certain characteristics, and the combination of DWI and DCE-MRI are helpful in the diagnosis.

Comparison study of clinicopathological features of cellular schwannoma between retroperitoneum and other sites

Background

Cellular schwannoma (CS) is a relatively rare neural tumor with few reports. This study aimed to compare the clinicopathological characteristics of CS in the retroperitoneum and other sites by analyzing the hematoxylin-eosin (HE) staining and immunohistochemical (IHC) staining results, to provide some help for pathological diagnosis.

Methods

A total of 79 CS cases from the Department of Pathology, Peking University International Hospital were collected, and the diagnosis was based on the 5^th WHO classification of soft tissue tumors. The staining results of HE and IHC were judged and analyzed according to the instructions. The t-tests, Chi-square test and Fisher's exact probability test were used for statistical analysis.

Results

Compared with other sites, the volume of retroperitoneal CS tumors were larger (t=4.265, P=0.001) and more likely to recur (χ²=4.223, P=0.04). Nerve sheath structures were rare around the tumors (χ²=60.096, P=0.000). Immunohistochemically, there was a difference in the expression of glial fibrillary acidic protein (GFAP), Cytokeratin (CK), and myelin basic protein (MBP) between the two groups (χ²=54.290, P=0.000; χ²=4.879, P=0.027; χ²=31.792, P=0.000). But there was no difference in expression between the two groups in the other indexes.

Conclusions

It founded that Retroperitoneal CS was often positive for GFAP and CK, suggesting it originated from unmyelinated Schwann cells. CS in other sites, the expression of GFAP and CK was often negative, indicating they derived from myelinated Schwann cells. The expression of MBP in the peripheral nerve sheath structure of CS can be used to determine whether the tumor originates from myelinated or unmyelinated Schwann cells. These findings may provide a reference for revealing pathogenesis, diagnosis and evaluating prognosis of CS.

Primary Urethral Malignant Peripheral Neural Sheath Tumor in a 58-Year-Old Female in the Absence of Neurofibromatosis Type 1

A malignant peripheral neural sheath tumor (MPNST) is a malignant soft tissue neoplasm with cellular origin arising from the outer lining of peripheral nerves. Approximately 10 cases have been identified to date where the lower urinary tract was affected. We discuss the case of a female patient that presented with primary MPNST that arose in the urethral tract in the absence of neurofibromatosis type 1 (NF1) or prior malignancies. This patient presented with pain and acute urinary tract symptoms secondary to urethral obstruction by a protruding vaginal mass. The patient underwent an incomplete initial resection to alleviate symptoms and to obtain a tissue diagnosis. Three months after the first hospitalization, the patient was re-hospitalized due to the recurrence of symptoms and subsequently underwent a complete tumor excision. The initial resection showed a 7.0 x 4.5 x 4.5 cm aggregate of tan-red to gray tumor masses. Microscopic examination showed a spindle cell neoplasm with malignant cytological features (hypercellularity, atypical mitoses, nuclear pleomorphism, and indistinct borders). Tumor cells stained positive for SOX10, S-100 (10% of tumor), with a "mosaic pattern" of H3K27ME3 (50% of tumor nuclei positive). Other lineage-specific and keratin markers stained negative. In the absence of other patient known primaries, the findings were consistent with a primary MPNST of the urinary tract. Residual tumor was identified on MRI scans one month after the follow-up. The completely excised tumor specimen on the second admission showed identical morphology when compared to the first specimen. While MPNSTs typically carry a poor prognosis, knowledge of behavior and prognosis of primary MPNSTs in the bladder is limited, due to the few relative numbers of available case reports. Further research is needed to study the clinical behavior, morphology, immunophenotypes, and genetics of primary MPNSTs arising from the lower urinary tract.

Loss of H3K27me3 expression in canine nerve sheath tumors

Nerve sheath tumors (NSTs) are characterized by neoplastic proliferation of Schwann cells, perineurial cells, endoneurial and/or epineurial fibroblasts. Diagnosis of NST is often challenging, particularly in distinguishing malignant NST (MNST) from other soft tissue sarcomas, or sometimes between low-grade MNST and benign NST. Recent studies in human pathology have demonstrated loss of trimethylation at lysine 27 of histone 3 (H3K27me3) in a subset of MNSTs using immunohistochemistry. Loss of H3K27me3 expression is rare in other high-grade sarcomas and also appears to be useful in distinguishing benign and low-grade MNSTs from high-grade subsets. In our retrospective study, we performed H3K27me3 immunohistochemistry in 68 canine tumors previously diagnosed as NST. We detected loss of H3K27me3 expression in 25% (n = 17) of all canine NST, including one neurofibroma, whereas 49% (n = 33) of tumors had mosaic loss of expression and 26% (n = 18) retained expression. No statistically significant differences were found between H3K27me3 expression, histopathological features of tumors, and their immunoreactivity for Sox10, claudin-1, GFAP, and Ki67. Because the classification of canine NST is not yet fully established and its correlation with the prognosis and clinical course of the disease is lacking, prospective studies with possible genetic analyses are needed to assess the true diagnostic value of H3K27me3 loss in canine NST.