Plexiform schwannoma

Schwannomas are benign tumors that arise from the peripheral nerve sheath. Many variants of schwannomas exist, including plexiform, epithelioid, cellular, glandular, and ancient. The pseudoglandular subtype is extremely rare, as fewer than five cases of cutaneous pseudoglandular schwannomas have been reported based on our literature review. Herein, we report a case of a 64-year-old female who presented with a skin-colored nodule on her right arm for several years. Histopathology showed a superficial and deep dermal nodulocystic neoplasm composed of epithelioid and spindle cells surrounded by a fibrous stroma...

The 2021 WHO classification of the CNS Tumors identifies as "Peripheral nerve sheath tumors" (PNST) some entities with specific clinical and anatomical characteristics, histological and molecular markers, imaging findings, and aggressiveness. The Task Force has reviewed the evidence of diagnostic and therapeutic interventions, which is particularly low due to the rarity, and drawn recommendations accordingly. Tumor diagnosis is primarily based on hematoxylin and eosin-stained sections and immunohistochemistry...

BACKGROUND: Plexiform neurofibromas can transform into atypical neurofibromas (ANF) and then further progress to aggressive malignant peripheral nerve sheath tumors (MPNST). ANF have been described to harbor distinct histological features and frequent loss of CDKN2A/B. However, histological evaluation may be rater-dependent, and detailed knowledge about the molecular mechanisms of malignant transformation is scarce. In general, malignant transformation can be accompanied by significant epigenetic changes, and global DNA methylation profiling is able to differentiate relevant tumor subgroups...

Glioma-associated oncogene 1 ( GLI1 ) alterations have been described in pericytoma with t(7;12), gastroblastoma, plexiform fibromyxoma, and an emerging class of GLI1 -rearranged or amplified mesenchymal neoplasms including "nested glomoid neoplasm". The immunophenotype of these tumor types is nonspecific, making some cases difficult to diagnose without sequencing. The utility of GLI1 immunohistochemistry (IHC) in distinguishing nested glomoid neoplasms and pericytomas with t(7;12) from morphologic mimics is unknown...

Neurofibromatosis type 1 (NF1) is a neurocutaneous condition with an autosomal dominant pattern of inheritance. This congenital disease is characterized by a wide spectrum of clinical manifestations and degree of severity. This case report describes a female patient in her early 20s who presented with a complaint of lumbosciatica-like pain evolving for several months. The condition initially escaped the attention of clinicians until a lumbar computed tomography scan and spinal magnetic resonance imaging were performed...

Malignant peripheral nerve sheath tumors (MPNST) are aggressive neoplasms, arising either sporadically, in the setting of neurofibromatosis type I (NF1) or post radiation. Most MPNST occur in adults and their pathogenesis is driven by the loss of function mutations in the PRC2 complex, regardless of their clinical presentation. In contrast, pediatric MPNST are rare and their pathogenesis has not been elucidated. In this study, we investigate a large cohort of 64 MPNSTs arising in children and young adults (younger than the age of 20 years) to better define their clinicopathologic and molecular features...

The seminal case report of plexiform melanocytic schwannoma, published a decade ago, indicated that this is a rare variant of schwannoma demonstrating immunohistochemical expression of melanocytic markers, electron microscopic evidence of melanosome formation, and genetic features of a benign schwannoma. We report herein, a second example of this entity. Of added interest, our case showed pseudoglandular features, as previously recorded in other variants of schwannoma. A 66-year-old man presented with a cutaneous papule on the abdomen...

BACKGROUND: Peripheral nerve sheath tumors (PNSTs), a rare group of neoplasms in the orbit, comprise only 4% of all orbital tumors. At present, there are very few studies detailing the features of these tumors identified using imaging technology. AIM: To compare the differences in location, morphology, magnetic resonance imaging (MRI) signal intensity/computed tomography (CT) value, and enhancement degree of tumors of different pathological PNSTs types. METHODS: Clinical, pathological, CT, and MRI data were analyzed retrospectively in 34 patients with periorbital sheath tumors diagnosed using histopathology from January 2013 to August 2021...

Schwannoma is a slow-growing nerve sheath tumour comprising differentiated neoplastic Schwann cells. The plexiform variant of schwannoma grows in a plexiform or multinodular pattern and may be conventional or of cellular type. Clinically, they manifest as single, skin-coloured tumours along the distribution of peripheral or cranial nerves. This tumour usually ranges between 2 and 4 cm in size, common sites of localization being the head or the flexor aspect of the extremities. The tumour may be associated with neurofibromatosis Type 2 (but not with neurofibromatosis Type 1)...

Schwannomas are tumors of the Schwann cells found in the myelin sheath. They cause 5% of all benign soft-tissue cancers, occur equally in males and females, and occur later in life. Since they remain asymptomatic, diagnosing and treating them becomes challenging; current guidelines recommend imaging followed by excision. Here, we present a case of a 19-year-old male who presents in an outpatient setting with a history of painless swelling of the fifth digit for the past four years. Past medical history and physicals are unremarkable...

Schwannoma is a rare benign soft tissue tumor that appears like a neuroma based on its specific location and clinical features. We report a case of a plexiform schwannoma in a middle-aged woman who had a painful bump located in the third webspace on the dorsum of her right foot for the last four years. Initially, the swelling was thought to be Morton's neuroma based on location and clinical feature findings. The mass was resected and was sent for histopathological examination, revealing a plexiform schwannoma, most likely developing from the cutaneous nerves on the dorsum of the foot...

Neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2) are autosomal dominant inherited neurocutaneous disorders or phakomatoses secondary to mutations in the NF1 and NF2 tumor suppressor genes, respectively. Although they share a common name, NF1 and NF2 are distinct disorders with a wide range of multisystem manifestations that include benign and malignant tumors. Imaging plays an essential role in diagnosis, surveillance, and management of individuals with NF1 and NF2. Therefore, it is crucial for radiologists to be familiar with the imaging features of NF1 and NF2 to allow prompt diagnosis and appropriate management...

BACKGROUND: Neurofibromatosis type 2 (NF2) is a genetic disease characterized by the appearance of multiple tumours in the nervous system. Cutaneous lesions are common and may provide useful diagnostic and prognostic information, but they have not been widely studied. OBJECTIVES: To characterize cutaneous lesions in a Spanish cohort of patients with NF2 and investigate associations with clinical and genetic severity. METHODS: We studied the clinical and histologic characteristics of cutaneous lesions in 49 patients with NF2 and analysed correlations with phenotype- and genotype-based severity scores...

Peripheral nerve sheath tumors (PNSTs) include schwannomas, neurofibromas (NFs), and plexiform neurofibromas (PNFs), among others. While they are benign tumors, according to their biological behavior, some have the potential for malignant degeneration, mainly PNFs. The specific factors contributing to the more aggressive behavior of some PNSTs compared to others are not precisely known. Considering that lipid homeostasis plays a crucial role in fibrotic/inflammatory processes and in several cancers, we hypothesized that the lipid asset was also unbalanced in this group of nerve tumors...

Over the past several years, management of the tumors associated with the neurofibromatoses has been recognized to often require approaches that are distinct from their spontaneous counterparts. Focus has shifted to therapy aimed at minimizing symptoms given the risks of persistent, multiple tumors and new tumor growth. In this review, we will highlight the translation of preclinical data to therapeutic trials for patients with neurofibromatosis, particularly neurofibromatosis type 1 and neurofibromatosis type 2...

Plexiform schwannoma (PS), a subtype of schwannoma, is a rare benign nerve sheath tumor characterized by a multinodular plexiform growth pattern. It is usually confined to the head and neck or skin. Pelvic PS is an extremely rare occurrence and signifies a challenge for the imaging diagnosis. In this work, we present a 42-year-old woman with pelvic PS, who was initially suspected of malignant tumor on 18F-FDG PET/MRI but confirmed as PS by postoperative pathology. We consider that this case would contribute to the literature and provide a further insight into diagnosing this kind of rare tumor...

Plexiform variants of neurofibromas and schwannomas are rare and typically arise in superficial soft tissues in the head and neck region. The treatment of these tumors is challenging and no generally accepted guidelines exist for their optimal management. The purpose of this study was to review the management and longterm prognosis of head and neck plexiform neurofibromas and schwannomas at 2 tertiary care academic hospitals in Finland over a 31-year period. The pathology files were searched for plexiform neurofibromas and schwannomas between the years 1990 and 2020...

Spitz nevi are indolent melanocytic tumors arising preferentially during and after childhood. Over the last decades, recurrent oncogenic drivers, sparsely detected in melanoma, were identified in Spitz melanocytic proliferations. Therefore, the detection of such drivers appears as a relevant diagnostic tool to distinguish both entities. Interestingly, morphologic features might correlate with the oncogenic drivers. Thus, the goal of this study was to assess the performances of previously identified morphological criteria to predict the presence of specific drivers...

Plexiform cellular schwannoma (PCS) is very rare, and it is not completely understood. We present our experience with 7 additional cases of PCS in infancy and childhood to further characterize its distinctive clinicopathological features. There were 5 females and 2 males with a mean age of 28 months (ranging, 2 months to 8 years). The involved sites included the left forearm ( n  = 2), sacrococcygeal region ( n  = 2), retroperitoneum ( n  = 1), thoracic spinal canal and thoracic cavity ( n  = 1), and neck ( n  = 1)...

BACKGROUND AND AIMS: Multinodular/plexiform schwannomas and neurofibromas of major nerves are rare: before surgery, differential diagnosis among these two uncommon variants is challenging. For both forms, surgical removal is recommended in case of progressive growth and worsening of neurological symptoms. Surgery has a higher risk of neurological damage than conventional schwannomas or neurofibromas. In literature, a comparison among these rare tumors is usually limited to the pathological aspect while specific surgical and clinical management indications are lacking...