An intraosseous malignant peripheral nerve sheath tumor of the lumbar spine without neurofibromatosis: Case report and review of the literature

Neurofibromatosis to neoplasia transition: a rare case report of spindle cell malignant peripheral nerve sheath tumor with literature review

Introduction and importance

Malignant peripheral nerve sheath tumor (MPNST) is a rare and aggressive soft tissue malignant tumor. MPNST in the spinal canal is rarely seen except in cases of neurofibromatosis type 1. However, a long-segment extradural spinal malignant spindle cell neoplasm has not been reported in the current literature.

Case presentation

We present the first reported case of spinal malignant spindle cell neoplasm extended along the spine. The detected lesion is responsible for compressing various segments of the spinal cord, causing thinning of the cord and secondary stenosis of the spinal canal, leading to a condition known as multisegment compression myelopathy.

Clinical discussion

MPNSTs are typically detected late due to nonspecific symptoms, with a higher incidence in extremities and a notable occurrence in unusual locations. Diagnosis relies on MRI and histopathology, with S_100 positivity as a neural marker. MPNSTs can arise from neurofibromas or Schwann cells, with a significant portion resulting from TP53 mutations or secondary to radiation exposure.

Conclusion

This case stands out due to its unique presentation, characterized by a predominantly spindle cell morphology with certain epithelioid features. It is imperative to recognize this condition for an accurate diagnosis, emphasizing the spindle cell-type MPNST and highlighting its exceptionally poor prognosis.

Malignant peripheral nerve sheath tumor of the maxilla: Case report and review of the literature with emphasis on its poor prognosis

Malignant peripheral nerve sheath tumor (MPNST) is a spindle cell sarcoma with poor prognosis. Although patients with neurofibromatosis type 1 (NF1) have a higher risk of MPNST, it can also occur in the sporadic setting and may rarely arise centrally within bone. In this study, we present an extremely rare case of intraosseous MPNST of the maxilla arising in a 38-year-old female with no history of NF1. Despite radical surgery and postoperative radiotherapy, the patient died due to multiple distant metastases 1 year after treatment. According to the results of the literature analysis performed in this study, maxillary MPNST cases have worse clinical outcomes than general MPNSTs. In addition, it seems that NF1 and histological necrosis are poor prognostic indicators in patients with maxillary MPNST.

Primary Malignant Peripheral Nerve Sheath Tumors of Bone: A Clinicopathologic Reappraisal of 8 Cases

Primary spindle cell and pleomorphic sarcomas of bone represent an exceedingly rare group of mesenchymal malignancies that include "soft tissue" histotypes, as malignant peripheral nerve sheath tumour. Outside the head and neck region, only 36 cases of primary malignant peripheral nerve sheath tumour of bone have been described. We retrieved from our archives eight cases of primary malignant peripheral nerve sheath tumour of bone arising outside the head and neck region, describing their clinical, radiological, and morphologic features. Our series, in which all but one patient died of diseases after a median of seven months, confirms that primary malignant peripheral nerve sheath tumours of bone are aggressive tumours. Pathologists should be aware of this rare histotype. More aggressive and active adjuvant treatments should be investigated.

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

Background

A definitive diagnosis of malignant peripheral nerve sheath tumor (MPNST) is challenging, especially in cases without neurofibromatosis 1 (NF1), because MPNST lacks specific markers on immunohistochemistry (IHC).

Methods

We performed IHC for histone 3 trimethylated on lysine 27 (H3K27me3) and evaluated the percentage of cells with H3K27me3 loss using measured values at 10% intervals, categorized as complete loss (100% of tumor cells lost staining), partial loss (10% to 90% of tumor cells lost staining), and intact (no tumor cells lost staining). We conducted fluorescence in situ hybridization (FISH) for NF1 and p16 deletions comparing 55 MPNSTs and 35 non-MPNSTs, consisting of 9 synovial sarcomas (SSs), 8 leiomyosarcomas (LMSs), 10 myxofibrosarcomas (MFSs), and 8 undifferentiated pleomorphic sarcomas (UPSs). We assessed the percentage of cells with homozygous and heterozygous deletions and defined “deletion” if the percentage of either the NF1 or p16 deletion signals was greater than 50% of tumor cells.

Results

Among the 55 MPNSTs, 23 (42%) showed complete H3K27me3 loss and 32 (58%) exhibited partial loss or intact. One each of the 9 SSs (11%), 8 LMSs (12%), and 8 UPSs (12%) showed complete H3K27me3 loss and many non-MPNSTs exhibited intact or partial H3K27me3 loss. Among the 55 MPNSTs, 33 (60%) and 44 (80%) showed NF1 or p16 deletion, respectively. Co-deletion of NF1 and p16 was observed in 29 (53%) MPNSTs. Among the 23 MPNTSs showing H3K27me3 complete loss, 18 (78%) and 20 (87%) exhibited NF1 or p16 deletion, respectively. Among the 32 MPNSTs with H3K27me3 partial loss or intact, 15 (47%) and 24 (75%) exhibited NF1 or p16 deletion, respectively. The frequency of NF1 and/or p16 deletion tended to be lower in non-MPNSTs than in MPNSTs. Approximately 90% of MPNSTs included cases with H3K27me3 complete loss and cases showing H3K27me3 partial loss or intact with NF1 and/or p16 deletion. Approximately 50% of MPNSTs showed co-deletion of NF1 and p16 regardless of H3K27me3 loss.

Conclusions

FISH for NF1 and p16 deletions, frequently observed in high-grade MPNSTs, might be a useful ancillary diagnostic tool for differentiating MPNST from other mimicking spindle cell and pleomorphic sarcomas.

Intraosseous Malignant Peripheral Nerve Sheath Tumor of 2 Consecutive Lumbar Vertebrae: A Case Report and Literature Review

BACKGROUND

Malignant peripheral nerve sheath tumor (MPNST), which refers to any malignant tumor that originates from peripheral nerve sheath cells, is rarely found in the spine. Primary intraosseous spinal MPNSTs are extremely uncommon; in fact, such an occurrence has been reported in a very limited number of cases hitherto. We report here one case of low-grade intraosseous MPNST in the lumbar vertebrae and review clinical research related to this rare tumor and modus operandi to its treatment.

CASE DESCRIPTION

A 51-year-old man suffering from lower back pain was initially diagnosed with lumbar tuberculosis. The intraoperative histopathologic examination, however, revealed that the occupying lesion was synovial sarcoma when surgeons intended to perform a debridement surgery of what was thought to be tuberculosis. The operation was therefore suspended. Two months later, the patient was referred to our institution. The pathologic sections were reexamined. Its results refuted the earlier thought of being synovial sarcoma, and a final diagnosis of MPNST was made. In addition, preoperative examination revealed that the tumor had advanced rapidly to the adjacent inferior vena cava and pedicle, which ruled out the possibility of performing a total en bloc spondylectomy. Therefore, a marginal resection for 2-level consecutive lumbar vertebrae was performed successfully via an anterior-posterior combined approach. No serious complications were detected at 18-month follow-up.

CONCLUSIONS

Preoperative biopsy is of great importance for the diagnosis of spinal tumors. Marginal resection of a complicated intraosseous spine MPNST via an anterior-posterior combined approach, despite being technically challenging, resulted in good survival and functional outcomes.

Malignant Peripheral Nerve Sheath Tumor of the Femur: A Rare Diagnosis Supported by Complete Immunohistochemical Loss of H3K27me3

The histological diagnosis of malignant peripheral nerve sheath tumor (MPNST) is challenging because of the wide morphological spectrum and suboptimal performance of conventional immunohistochemical markers. MPNST arising primarily in the bone is exceptional, and its definitive diagnosis, particularly out of the neurofibromatosis type 1 (NF1) context, is even more problematic. Recurrent inactivation of EED or SUZ12 in a majority of MPNSTs results in a complete loss of trimethylated histone H3 at lysine 27 (H3K27me3) immunoreactivity, making it a highly specific biomarker of MPNSTs. In this article, we report a case of sporadic MPNST of the proximal femur that showed complete loss of H3K27me3. The patient was treated with limb-sparing surgery and postoperative radiotherapy. He developed multiple lung and bone metastases 4 months after surgery. Our case confirms the utility of H3K27me3 immunohistochemistry to yield a definitive diagnosis of sporadic MPNST in a rare primary site.

Immunohistochemical features of giant cell ependymoma of the filum terminale with unusual clinical and radiological presentation

BACKGROUND

Giant cell ependymoma of the filum terminale is a rare variant, generally manifested as a well-circunscribed intradural mass with an indolent biological behavior.

CASE PRESENTATION

We describe the case of a 48-year-old Mexican female who non-relevant past medical history, that developed a GCE of the filum terminale. Magnetic resonance imaging and computed tomography revealed the presence of an intra-axial tumor extending from L3 to L5 with extra-medullary invasion. Therefore the tumor was considered unresectable and only incisional biopsy was obtained, establishing the tentative diagnosis of a poorly differentiated neoplasia. A second evaluation of the case revealed the presence of numerous non-cohesive pleomorphic giant cells with intranuclear inclusions and broad eosinophilic cytoplasm, alternating with intermediate size cells with round, hyperchromatic nuclei and forming a perivascular pseudo-rosettes pattern. The ependymal phenotype was supported by light microscopy and corroborated by immunohistochemistry analysis. The patient was subsequently treated with radiotherapy 54Gy. She is alive after a 27-month follow-up, with residual disease, difficulty ambulating and pain.

CONCLUSIONS

GCE of filum terminale may have an atypical clinical and radiological presentation, albeit with invasive characteristics and anaplasia on histologic analysis. However, its biological behavior is indolent and associated to longer survival. Due to the presence of giant cells, the differential diagnosis of other primary neoplasias at that site were considered, including paraganglioma, malignant peripheral nerve sheath tumors as well as metastatic malignant melanoma, adrenal carcinoma, thyroid gland carcinoma and urothelial carcinoma, that may all harbor giant cells.