Spinal melanotic schwannoma: a tumour with poor prognosis

Case Report: Cutaneous melanocytic schwannoma with concomitant melanocytoma in a canine

Schwannoma is a nerve sheath tumour arising from differentiated Schwann cells, and melanocytic schwannoma (MS) is a rare variant where the Schwan cells produce melanin pigment. MS is typically associated with spinal nerve roots and there have been only ~20 reports of cutaneous or subcutaneous MS to-date in humans. In canines, there have only been two reports of MS, both associated with spinal root nerves. In this report, we describe a 7-year-old Weimaraner cross breed dog that presented with two pigmented lesions on the eyelids. The lesions were surgically removed and histological analysis revealed well-circumscribed, non-encapsulated, expansile, neoplasms that were displacing most of the dermis and adnexa. The first lesion was composed of spindloid cells arranged in short interlacing streams with large amounts of pale eosinophilic cytoplasm that sometimes contained fine melanin granules. In areas there were spindle cells arranged in verocay bodies which led to a diagnosis of MS. In contrast, the second lesion was composed of polygonal cells arranged in thick sheets with large amounts of pale eosinophilic cytoplasm that sometimes contained fine melanin granules. The diagnosis was melanocytoma (which is one of the macroscopic differential diagnoses for MS). Whilst melanocytoma is a commonly occurring cutaneous lesion in canines and surgical removal is considered curative, due to little being known about MS in dogs, the outcome remained guarded, as MS in humans has an unpredictable nature, and recurrence and metastasis have been reported.

Peripheral nerve tumors

The chapter is focused on the neoplastic peripheral nerve lesions, which primarily involve "cranial and paraspinal nerves," as outlined in the CNS volume (WHO_Classification_of_Tumours_Editorial_Board, 2021). These include classic peripheral nerve sheath tumors such as schwannoma, neurofibroma, intraneural perineurioma, and malignant peripheral nerve sheath tumors, with their variants as well as new and more precisely defined entities, including hybrid nerve sheath tumors and malignant melanotic nerve sheath tumor (previously melanotic schwannoma).

Malignant Melanotic Nerve Sheath Tumors: A Review of Clinicopathologic and Molecular Characteristics

Malignant melanotic nerve sheath tumor (MMNST) which was formerly known as melanocytic schwannoma, is an uncommon aggressive type of nerve sheath tumor. It originates from nerve roots with clonal Schwann cell proliferation and melanin pigment production. MMNST which was once thought to be a benign tumor is now considered a malignant disease based on the latest 2020 World Health Organization classification of soft tissue tumors. Interestingly, despite the histologic features appearing benign with a low proliferation index, the clinical course of this tumor is malignant, which was demonstrated in case series with high rate of recurrences and metastasis. This tumor can occur sporadically or in patients with an underlying familial predisposition syndrome called, Carney's complex. Affected patients will often harbor a germline mutation in the PRKAR1A gene. MMNST can be histologically difficult to distinguish from malignant melanoma, other melanocytic tumors, and Schwannoma. Having a better understanding of its clinic pathologic characteristics and associated conditions is essential in properly diagnosing and managing affected individuals. This includes the possible need for genetic testing to detect germline mutations, genetic counseling, and surveillance according to published recommendations. In this article, we summarize the clinic pathologic and molecular features of MMNST and discuss what is known about its molecular biology and its associations with predisposing conditions. The review was conducted through an extensive PubMed search using keywords then relevant publications were selected.

A Radiologist's Guide to the 2021 WHO Central Nervous System Tumor Classification: Part 2-Newly Described and Revised Tumor Types

The fifth edition of the World Health Organization classification of tumors of the central nervous system (CNS), published in 2021, introduces major shifts in the classification of brain and spine tumors. These changes were necessitated by rapidly increasing knowledge of CNS tumor biology and therapies, much of which is based on molecular methods in tumor diagnosis. The growing complexity of CNS tumor genetics has required reorganization of tumor groups and acknowledgment of new tumor entities. For radiologists interpreting neuroimaging studies, proficiency with these updates is critical in providing excellent patient care. This review will focus on new or revised CNS tumor types and subtypes, beyond infiltrating glioma (described in part 1 of this series), with an emphasis on imaging features.

The Recent Advances in Molecular Diagnosis of Soft Tissue Tumors

Soft tissue tumors are rare mesenchymal tumors with divergent differentiation. The diagnosis of soft tissue tumors is challenging for pathologists owing to the diversity of tumor types and histological overlap among the tumor entities. Present-day understanding of the molecular pathogenesis of soft tissue tumors has rapidly increased with the development of molecular genetic techniques (e.g., next-generation sequencing). Additionally, immunohistochemical markers that serve as surrogate markers for recurrent translocations in soft tissue tumors have been developed. This review aims to provide an update on recently described molecular findings and relevant novel immunohistochemical markers in selected soft tissue tumors.

Magnetic resonance imaging features and clinical course of malignant melanotic nerve sheath tumors: single institution experience over two decades

OBJECTIVE

To evaluate MR features and clinical course of malignant melanotic nerve sheath tumor (MMNST), previously known as melanotic schwannoma and considered indolent and rarely metastasizing.

MATERIALS AND METHODS

This IRB-approved retrospective study searched 31 patients (20 male: 11 female, mean age 48; range 15-76) with histologically confirmed MMNST in a single tertiary cancer center over 22 years. Pre-treatment MR was available in 12 patients and evaluated by two radiologists in consensus regarding lesion location, size, morphology, signal characteristics, contrast enhancement, local invasion, and presence of classic signs of peripheral nerve sheath tumors. Clinical outcomes, including local recurrence, metastasis, and survival, were examined in 12 patients for whom follow-up was available.

RESULTS

The spine was the most frequent site (13/31) among all identified cases. In 12 cases with MR, lesions were well-circumscribed in 11/12 cases, with a mean size of 4.5 cm (2.3-13.0 cm). Ten of 12 cases showed T1 hyperintensity. In 5/9 spinal MRI, tumor involved multiple levels. All lesions showed contrast enhancement, and local bone invasion in > 50%. A dumb-bell shape was common to all spinal lesions. Classical signs of nerve sheath tumors were uncommon. Among 12 patients with a mean follow-up of 4.8 years (range 1.3-10.2 years), six were disease-free, while two had recurrence or metastases, and four had died of metastases.

CONCLUSION

MMNST usually presents as a T1 hyperintense enhancing dumb-bell shaped mass in the spine. Multi-level involvement and bone invasion are common. MMNST is clinically aggressive with high rates of metastases and death.

Sporadic spinal psammomatous malignant melanotic nerve sheath tumor: A case report and literature review

Background

Sporadic Spinal Psammomatous Malignant Melanotic Nerve Sheath Tumor (SSP-MMNST) is a rare subgroup of peripheral nerve sheath tumors arising along the spine. Only a few reports of SSP-MMNST have been described. In this paper, we review the literature on SSP-MMNST focusing on clinical, and diagnostic features, as well as investigating possible pathogenetic mechanisms to better implement therapeutic strategies. We also report an illustrative case of a young female presenting with cervicobrachial pain due to two SSP-MMNSTs arising from C5-6 right spinal roots.

Case description

We report a case of a 28-year-old woman presenting with right arm weakness and dysesthesia. Clinical examination and neuroimaging were performed, and, following surgical removal of both lesions, a histological diagnosis of SSP-MMNST was obtained.

Results

The literature review identified 21 eligible studies assessing 23 patients with SSP-MMNST, with a mean onset age of 41 years and a slight male gender preference. The lumbar district was the most involved spinal segment. Gross-total resection (GTR) was the treatment of choice in all amenable cases, followed in selected cases with residual tumor by adjuvant radiotherapy or chemotherapy. The metastatic and recurrence rates were 31.58% and 36.8%, respectively.

Conclusion

Differently from common schwannomas, MMNST represents a rare disease with known recurrence and metastatization propensity. As reported in our review, SSP-MMNST has a greater recurrence rate when compared to other forms of spinal MMNST, raising questions about the greater aggressiveness of the former. We also found that residual disease is related to a higher risk of systemic disease spreading. This metastatic potential, usually associated with primary lumbar localization, is characterized by a slight male prevalence. Indeed, whenever GTR is unachievable, considering the higher recurrence rate, adjuvant radiation therapy should be taken into consideration.

Malignant psammomatous melanotic schwannoma mimicking adrenal cyst: case report

Background

Melanotic schwannoma is a melanin producing nerve sheath tumors. Rarely, it can be associated with psammoma bodies, called psammomatous melanotic schwannoma. Psammomatous melanotic schwannomas are associated in up to 10% of the cases with Carney’s syndrome. The rarity of the lesion, which may present at different localizations create difficulty in placing a correct initial diagnosis. Definitive diagnosis is made after complete tumor excision and pathomorphological evaluation. The prognosis depends on the anatomical localization, local invasion and presence of a high mitotic index. The main pathomorphological differential diagnosis includes schwannomas and other melanin producing tumors as melanoma.

Case presentation

We present a case of an 11-year-old female with cystic lesion adjacent to right adrenal gland, mimicking adrenal cyst. Ultrasound guided biopsy was undertaken due to the cystic appearance of the formation and the lack of certain diagnosis from the non-invasive diagnostic tests. No signs of cellular and nuclear atypism were observed. The diagnosis of benign endothelial cyst with spontaneous hemorrhage was suggested. The patient underwent transabdominal laparoscopic adrenalectomy en-bloc with the cyst to prevent spillage of the cyst content due to the intimate adhesion of the lesion to the adrenal gland and vena cava inferior. Pathomorphological examination revealed malignant psammomatous melanotic schwannoma. The adrenal gland was intact with no tumor infiltration. The patient was followed up on the 1st and 2nd month afterwards the surgery by MRI with no signs of local recurrence and postoperative complications.

Conclusion

Psammomatous melanotic schwannoma near adrenal gland are rare and present difficulty with exact preoperative diagnosis. Complete resection should always be provided. Laparoscopic surgery is feasible if radical excision is not compromised. Long-term follow-up and Carney’s syndrome surveillance after complete excision are recommended especially in young patients.

A Rare Case of Melanotic Schwannoma Occurred Intraosseous of Sacrum: A Literature Review

BACKGROUND

Melanotic schwannoma is a rare tumor when it occurs in the sacrum. Though it is mostly classified as benign, the prognosis is unpredictable due to the possibility of recurrence and metastasis. Here, we reported a case of intraosseous of sacrum with good results and reviewed the literature.

CASE PRESENTATION

A 33-year-old male patient complained of low back pain and was discovered to have an obstruction at S2. Following the necessary imaging diagnosis, we treated the patient with piecemeal excision in conjunction with extended curettage, and the frozen biopsy revealed that the tumor was melanotic schwannoma. The intraosseous portion of the lesion was curettaged using high-speed drill to enlarge the edge of curettage, and piecemeal excision for lesion within the sacral canal. After surgery, the patient received total 56Gy radiotherapy and frequent follow-up. After 15 months follow-up, there was no evidence of recurrence, and the nerve function was normal.

CONCLUSION

Melanotic schwannoma that occurs intraosseous of the sacrum is extremely rare and lacks typical clinical manifestations; however it can be identified through careful pathological and imaging diagnosis. Intralesional extended curettage combined with radiotherapy can achieve a good local control with a satisfactory clinical effect in this rare disease.

Malignant Melanotic Nerve Sheath Tumor

Malignant melanotic nerve sheath tumors are uncommon pigmented tumors of Schwann cell origin, most often found along the spinal nerves. Although well-described in the literature, the tumors are quite rare, making up <1% of nerve sheath tumors. Physicians are, therefore, often unfamiliar with both the appearance and the optimal treatment of such tumors. Morphologically, many imaging features overlap with schwannomas and neurofibromas. Nevertheless, the malignant melanotic nerve sheath tumors are crucial to identify. They can be extremely aggressive, and the management of these tumors is considerably different from their benign counterparts. In this radiology-pathology review, we will highlight the imaging appearance, histologic features, surgical resection, and subsequent therapeutic strategies in a patient with a lumbar malignant melanotic nerve sheath tumor.

Benign Peripheral Non-cranial Nerve Sheath Tumors of the Neck

Benign peripheral non-cranial nerve sheath tumors are rare lesions, including both schwannomas and neurofibromas. These tumors arise from Schwann cells, and may originate from any peripheral, cranial, or autonomic nerve. Most of them are localized and sporadic but multifocal systemic forms can occur. Cervical sympathetic chain, brachial plexus, cervical plexus and spinal roots and nerves are the major nerve systems commonly affected. Dumbbell-shaped intra- and extradural tumors occur most commonly in the cervical spine, as well as purely extradural and paravertebral tumors. The management of these tumors has improved greatly owing to the developments in imaging techniques and surgical innovations such as endoscopically assisted approaches and robotic surgery. Microsurgical intracapsular excision of the tumor helped by the use of intraoperative fluorescent dyes and intraoperative neurophysiological monitoring minimize postoperative neural deficit, since most schwannomas are encapsulated. Most tumors can be removed with a low rate of complications and recurrence. Radiotherapy should be considered for growing lesions that are not amenable to surgery. In asymptomatic patients, observation and serial scans is an option for elderly infirm patients.

A para-aortic malignant melanotic nerve sheath tumor mimicking a gastrointestinal stromal tumor: a rare case report and review of literature

Background

Malignant melanotic nerve sheath tumor (MMNST), formerly called melanotic schwannoma, is a rare tumor of neural crest derivation which most frequently arises from the region of spinal or autonomic nerves near the midline. Recent studies have reported malignant behavior of MMNST, and there still has no standard management guidelines. Intra-abdominal MMNST, which has never been reviewed as an entity, is even rarer. In this study, we present a rare case of a cystic MMNST arising from the para-aortic region and mimicking an intra-abdominal gastrointestinal stromal tumor (GIST), and review the literature regarding MMNSTs located in the abdominal cavity.

Case presentation

A 59-year-old female was incidentally found a tumor located in the left para-aortic area by non-contrast computed tomography. A Magnetic Resonance Imaging showed a cystic mass originated from the inferior mesenteric artery (IMA) territory. A GIST was initially diagnosed. The tumor was resected en bloc by laparoscopic surgery and was found between mesocolon and Gerota’s fascia with blood supply of IMA. Grossly, dark brown materials were noted at the inner surface of the cystic wall. Microscopically, the tumor cells were melanin-containing, and no psammomatous bodies were present. Immunohistochemically, the tumor showed positivity for MART1, HMB45, collagen IV, and SOX10, and negativity for AE1/AE3. MMNST was favored over malignant melanoma, since the tumor was located near ganglia and had cells with less atypical cytology and a low mitotic rate, and subsequent adjuvant radiotherapy was performed. The patient was alive with no evidence of recurrent or metastatic disease 11 months after radiotherapy.

Conclusions

Our review of abdominal MMNST cases showed a female predominance, with an average age of 54.8 years, and a trend toward being a larger tumor showing cystic or necrotic changes. Local recurrence and metastasis rate were reviewed, and both showed a low rate. Diagnosis of MMNST should combine all the available findings, and complete excision of the tumor should be performed, followed by long-term patient monitoring.

Practical Approach to Histological Diagnosis of Peripheral Nerve Sheath Tumors: An Update

Peripheral nerve sheath tumors encompass a wide spectrum of lesions with different biological behavior, including both benign and malignant neoplasms as well as the recent diagnostic category, i.e., “atypical neurofibromatous neoplasm with uncertain biologic potential” to be used only for NF1 patients. Neurofibromas and schwannomas are benign Schwann-cell-derived peripheral nerve sheath tumors arising as isolated lesions or within the context of classical neurofibromatosis or schwannomatoses. Multiple tumors are a hallmark of neurofibromatosis type 1(NF1) and related forms, NF2-related-schwannomatosis (formerly NF2) or SMARCB1/LZTR1-related schwannomatoses. Perineuriomas are benign, mostly sporadic, peripheral nerve sheath tumors that show morphological, immunohistochemical, and ultrastructural features reminiscent of perineurial differentiation. Hybrid tumors exist, with the most common lesions represented by a variable mixture of neurofibromas, schwannomas, and perineuriomas. Conversely, malignant peripheral nerve sheath tumors are soft tissue sarcomas that may arise from a peripheral nerve or a pre-existing neurofibroma, and in about 50% of cases, these tumors are associated with NF1. The present review emphasizes the main clinicopathologic features of each pathological entity, focusing on the diagnostic clues and unusual morphological variants.

Nevus, melanoma or something else? Mesenchymal neoplasms with melanocytic differentiation

The overwhelming majority of cutaneous neoplasms with melanocytic differentiation are nevi, melanomas and more rarely melanocytomas. Nevertheless, there is also a group of mesenchymal neoplasms with genuine melanocytic differentiation which can create diagnostic difficulties with significant repercussions. These can rarely present as primary or metastatic cutaneous lesions. Theones that are relevant to a dermatopathologist include malignant melanotic nerve sheath tumor, perivascular epithelioid cell neoplasm and clear cell sarcoma. This work will provide a thorough review of clinical presentation, morphologic and immunohistochemical features as well as molecular pathogenesis of these tumors. We hope to familiarize the general dermatopathology readership with a group of neoplasms of mesenchymal lineage exhibiting melanocytic differentiation and ultimately avoid diagnostic misadventures. This article is protected by copyright. All rights reserved.

Post-operative Stereotactic Radiosurgery of Malignant Melanotic Schwannoma

Melanotic schwannoma is an extremely rare schwannoma variant with malignant potential, demonstrating high local and distant recurrence. Given the paucity of data, recommended treatment with localized disease is radical resection, with the unclear benefit of adjuvant therapy. We present a case of an 18-year-old female with no past medical history or genetic syndromes who underwent margin-positive resection of an S1 nerve root melanotic schwannoma followed by adjuvant stereotactic radiosurgery (SRS). SRS was delivered without acute or late toxicity by 2.5 years post-treatment. She remains without evidence of recurrent disease, although longer follow-up is needed given the risk of late recurrence. Our case adds to the limited literature documenting the efficacy of adjuvant radiotherapy in melanotic schwannoma and is the first to describe the successful use of SRS for this rare disease.

Malignant melanotic nerve sheath tumor in pleural effusion: Deceitful cytology with significant repercussions

Malignant melanotic nerve sheath tumor (MMNST) is an exceedingly rare and aggressive neoplasm of Schwann cell origin that has seldom been described in the cytopathology literature. Herein we present a case of a 60-year-old female with a 3.8 cm presacral mass that was diagnosed as a MMNST. A molecular workup demonstrated TERT promoter -124C > T and TET2 Q891* gene mutations. Within 2 years of her initial diagnosis, she had developed widespread metastasis and pleural effusions. A cytologic workup of the pleural fluid revealed clusters of vacuolated epithelioid cells with enlarged nuclei, prominent nucleoli, and occasional multinucleation. The lesional cells were positive for SOX10, S100-protein, Melan-A, and HMB45, while negative for Calretinin, MOC31, and monoclonal CEA. In this clinicopathologic context, a diagnosis of metastatic MMNST was rendered. Awareness of this entity and its clinical presentation, along with a critical understanding of its molecular findings and that of imitators, is crucial in achieving an accurate diagnosis.

Mesenchymal Tumors of the Mediastinum: An Update on Diagnostic Approach

Mesenchymal tumors of the mediastinum are a heterogenous group of rare tumors with divergent lineages. Mediastinal mesenchymal tumors are diagnostically challenging due to their diversity and morphologic overlap with nonmesenchymal lesions arising in the mediastinum. Accurate histologic diagnosis is critical for appropriate patient management and prognostication. Many mediastinal mesenchymal tumors affect distinct age groups or occur at specific mediastinal compartments. Neurogenic tumors, liposarcoma, solitary fibrous tumor, and synovial sarcoma are common mesenchymal tumors in the mediastinum. Herein, we provide an update on the diagnostic approach to mediastinal mesenchymal tumors and a review of the histologic features and differential diagnosis of common benign and malignant mesenchymal tumors of the mediastinum.

Checkpoint inhibitors and radiotherapy in refractory malignant melanocytic schwannoma with Carney complex: first evidence of efficacy

Melanocytic schwannoma (MS) is a rare nerve sheath tumour characterised by melanin-producing neoplastic schwann cells that typically affects the posterior spinal nerve roots. We report an ultrarare case of recurrent/metastatic MS associated with Carney complex in a young woman with family history of breast cancer. This highlights the novel approach of combined checkpoint inhibitors (CPI) and radiotherapy. The patient was initially treated with Nivolumab along with concurrent external beam radiotherapy. There was sustained clinical benefit achieved for over 15 months with preserved quality of life. Addition of Ipilimumab, which she tolerated reasonably well, helped to control the progressive disease again for another 12 months. She harboured a rare PRKAR1A R228 mutation (Carney complex) and received appropriate targeted therapy. She survived for 51 and 35 months from her initial diagnosis and start of CPI, respectively, which to the best of our knowledge is the longest documented survival in this rare entity.

Hemorrhagic spinal melanotic schwannoma presenting as acute chest pain: A case report and literature review

Background:

Melanotic schwannoma (MS) is a rare variant of peripheral nerve sheath tumor. MS commonly arises along the spinal nerve sheath. Patients most often experience pain along the dermatome of the affected nerve root. Symptoms development is usually insidious. About half of MS cases are associated with Carney complex, a multi-neoplastic disorder. The remaining cases arise spontaneously. About 10–44% of these tumors undergo malignant transformation.

Case Description:

We describe a case of hemorrhagic MS presenting as acute chest pain mimicking myocardial infarction, a presentation which has not yet been described in the literature. Neurologic examination did not reveal any abnormalities. Myocardial infarction was ruled out in the ER, and a chest CT angiogram was ordered for evaluation of PE or aortic dissection which revealed an intradural extramedullary dumbbell-shaped mass extending through the left vertebral foramen at the level of T8. MRI revealed a heterogenous mass that was hyperintense with T2 and hypointense with T1-weighted imaging. The patient underwent an open laminectomy of the left T8 and T9 vertebrae and gross total resection (GTR) of a hemorrhagic black tumor. Microscopic examination showed fascicles and nests of plump spindle cells with variable intracellular melanin. Immunohistochemistry showed the cells to be positive for S100, SOX10, HMB-45, and MART-1, confirming diagnosis of MS. Two months after the operation, the patient was doing well and is free of recurrence.

Conclusion:

GTR is considered the optimal treatment for MS; radiotherapy and chemotherapy may be considered but have not been shown to improve patient outcomes.

18F-FDG PET/CT imaging for aggressive melanotic schwannoma of the L3 spinal root: A case report

RATIONALE

Melanotic schwannoma (MS) is an unusual variant of a nerve sheath neoplasm that accounts for less than 1% of all primary peripheral nerve sheath tumors. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has unique value in detecting malignant MS lesions. To date, only 4 cases of MS with hepatic metastasis have been reported. Herein, we report the fifth case, which is the first reported patient with MS of Asian ethnicity with hepatic metastasis.

PATIENT CONCERNS

A 29-year-old woman with a 1-day history of backache was admitted to our hospital. PET/CT showed a paravertebral heterogeneous soft tissue mass along the spinal nerve at the L2-L3 level with strong FDG uptake, and a nodule with increased FDG uptake in the lateral lobe of the left liver.

DIAGNOSIS

A puncture biopsy of the L3 bony destruction and surrounding soft tissue mass was performed. The final diagnosis was spinal MS with hepatic metastasis.

INTERVENTIONS

The patient underwent 6 courses of systemic chemotherapy.

OUTCOMES

The patient did not receive further treatment for half a year after the end of chemotherapy and recovered well.

LESSONS

Unlike conventional schwannomas, which are completely benign, MS has an unpredictable prognosis. It is thought to have low malignant potential, and the malignant type tends to metastasize. FDG PET/CT has a unique and important value in the differential diagnosis of benign and malignant lesions, in detecting occult metastases, monitoring the treatment response, and assessing the prognosis of MS.

Asymptomatic Left Ventricular Malignant Psammomatous Melanotic Schwannoma

Malignant psammomatous melanotic schwannoma (MPMS) is a rare type of tumour, occasionally reported to occur with mediastinal involvement. Histopathologic similarities with melanoma may lead to a wrong diagnosis, but distinguishing between types of tumours is mandatory for adequate management and prognosis. MPMS may be aggressive and manifest unpredictable behavior, with a poor midterm prognosis despite benign histopathologic features. We discuss the challenges that come with a diagnosis of MPMS, and the rationale for our treatment strategy, in this first report regarding MPMS involving the left heart ventricle.

Novel response to neoadjuvant anti-PD1 therapy for a patient with retrocaval melanotic schwannoma

Melanotic schwannoma is a rare nerve sheath tumor composed of melanin-producing Schwann cells with the potential for metastasis. These tumors can be associated with familial tumor syndromes and can cause significant symptoms related to nerve compression and mass effect. Due to the rarity of these lesions, they can be initially misidentified as melanocytomas, pigmented dermatofibrosarcoma protuberans, neurofibromas or malignant melanomas. Surgical excision is the mainstay of treatment with limited benefit from adjuvant systemic chemotherapy or radiation. Modern treatments with immune checkpoint blockade have demonstrated significant improvements in progression-free and overall survival for a variety of cancer histologies; however, anti-PD1 therapy has yet to be evaluated in patients with melanotic schwannoma. This report demonstrates a significant improvement in symptomatology and tumor stability with neoadjuvant anti-PD1 therapy for a retrocaval melanotic schwannoma initially masquerading as malignant melanoma. This report demonstrates the potential benefit of a novel therapeutic option for patients with melanotic schwannoma.

The 2020 WHO Classification of Tumors of Soft Tissue: Selected Changes and New Entities

Soft tissue tumors are a relatively rare and diagnostically challenging group of neoplasms that can have varying lines of differentiation. Accurate diagnosis is important for appropriate treatment and prognostication. In the 8 years since the publication of the 4th Edition of World Health Organization (WHO) classification of soft tissue tumors, significant advances have been made in our understanding of soft tissue tumor molecular biology and diagnostic criteria. The 5th Edition of the 2020 WHO classification of tumors of soft tissue and bone incorporated these changes. Classification of tumors, in general, but particularly in soft tissue tumors, is increasingly based on the molecular characteristics of tumor types. Understanding tumor molecular genetics improves diagnostic accuracy for tumors that have been difficult to classify on the basis of morphology alone, or that have overlapping morphologic features. In many large hospitals in the United States and Europe, molecular tests on soft tissue tumors are a routine part of diagnosis. Therefore, surgical pathologists should be familiar with newly emerging molecular genetic techniques in clinical settings. In the near future, molecular tests, particularly in soft tissue tumor diagnosis, will become as routine during diagnosis as immunohistochemistry is currently. This new edition provides an updated classification scheme and essential diagnostic criteria for soft tissue tumors. Newly recognized entities and subtypes of existing tumor types, several reclassified tumors, and newly defined molecular and genetic data have been incorporated. Herein, we summarize the updates in the WHO 5th Edition, focusing on major changes in each category of soft tissue tumor, and the newly described tumor entities and subtypes.

Extramedullary malignant melanotic schwannoma of the spine: Case report and an up to date systematic review of the literature

BACKGROUND

Melanotic schwannoma is a rare variant of schwannoma. Extramedullary melanotic schwannoma originates in the vicinity of nerve roots mimicking other intervertebral disc disorders. Therefore, T1 and T2-weighted MRI sequences become an essential tool for diagnosis. Aside from case reports, no large studies exist to provide consensus on the signal intensities in T1 and T2-weighted MR imaging. Moreover, no clear evidence is available to delineate prognosis. Here, a case report is presented together with a subsequent systematic review of the literature regarding this rare entity.

CASE DESCRIPTION

A 45-year old female presented with a one-year history of insidious onset of neck pain and paraesthesia. Magnetic resonance imaging confirmed an extramedullary lesion along the C6 nerve root with T1-weighted hyperintensity and T2-weighted hypointensity. Despite two surgical decompressions and adjuvant immunotherapy, the patient unfortunately passed away due to metastatic progression.

DISCUSSION

According to the systematic review conducted, in over half of the cases of extramedullary melanotic schwannoma, there is local reoccurrence and/or distal metastasis. Moreover, in 64.7% and 70.6% of the cases, the T1-weighted image of the lesion appears hyperintense and hypointense on a T2-weighted image, respectively. It is an aggressive variant of schwannoma, one of the most commonly observed extramedullary tumours presenting to neurosurgical practice.

CONCLUSION

Our results highlight that specific T1 and T2-weighted imaging findings can provide valuable information, enabling early suspicion, influencing the surgical aims and strategy and the timely commencement of relevant immunotherapy. Considering the poor prognosis, early adjuvant therapy with other modalities should be considered.

A Rare Case of Hemorrhagic Melanotic Schwannoma in a 38-year-old Female

Melanotic schwannoma is a rare form of nerve sheath tumor composed of melanin-producing neoplastic Schwann cells. Less than 200 cases have been reported worldwide. The entity has been associated with Carney complex, a rare genetic disorder characterized by multiple benign tumors. A 38-year-old female presented to our unit with sudden-onset lower back pain and radiculopathy triggered by a mechanical injury. Imaging demonstrated a lesion within the left L5/S1 neural exit foramen with remodeling of bony architecture typical of a chronic, benign process. She proceeded for resection and histology revealed a psammomatous melanotic schwannoma. The patient recovered well with improvement in symptomology. Due to the aggressive nature of the disease, she remains under surveillance for local recurrence and distant metastasis. Clinicians should be aware of this malignant entity, despite its possible presentation with radiological features of a chronic, benign process. Unusual characteristics such as hemorrhage should be treated with a high index of suspicion.

Melanotic Schwannoma, a Deceptive Misnomer for a Tumor With Relative Aggressive Behavior: A Series of 7 Cranial and Spinal Cases

The authors present in this article a series of 7 intracranial/spinal cases of melanotic schwannomas that highlight the aggressive nature of these tumors. The series comprises 2 males and 5 females, age range 19 to 50 years, with spinal/paraspinal location in 4/7 (57%), and intracranial (along the trigeminal nerve) location in 3/7 (43%). There was no association with Carney's complex. All the cases showed similar histology of epithelioid to spindled cytomorphology with vesicular nuclei (including prominent nucleoli) and conspicuous intracytoplasmic melanin pigment. Mitotic activity was seen in 3/7 cases (43%), 2 of which showed atypical forms. Immunohistochemically, all the cases were positive for S100 protein, HMB-45, melan-A and p16 protein; while negative for PDL1. Ki-67 labeling index was >5% in cases with mitotic activity. Two cases were asymptomatic (after 2.5 and 5 years postsurgery), 2 cases (one was mitotically active, while the other had no mitosis) had recurrence 6 months and 3.5 years after initial surgery, respectively, probably suggesting that mitosis alone may not be a robust predictor of biological behavior. These patients were treated with various adjuvant modalities and were alive for 4 years and 3 years of post-therapy period, respectively. Three patients were offered adjuvant radiotherapy, based on presence of aggressive histological features or significant residual tumor. One showed good clinical response. This series highlights the variability of clinical behavior of these neoplasms belying a deceptively bland nomenclature and also highlights the lack of correlation between histological features and biological behavior.

Brain and spine melanotic schwannoma: A rare occurrence and diagnostic dilemma

PURPOSE

Melanotic schwannoma (MS) was formerly known as a rare variant of schwannoma. The behavior of MS is unpredictable, with a tendency for recurrence and metastasis. The purpose of this study was to illustrate the imaging characteristics of these rare and misdiagnosed tumors. The prognosis of MS is discussed, along with the importance of follow-up exams to assess for recurrence and metastasis. Furthermore, we compare our results with those previously published on MS in order to have a better understanding of this rare entity.

METHODS

Three MS cases were encountered between 2008 and 2015 at our institute. All available data were reviewed, including the clinical history, imaging findings, operative notes, and the histopathology results. A follow-up magnetic resonance imaging (MRI) scan was also reviewed up to 23 months post surgery to assess for recurrence.

RESULTS

Three cases of MS are included: one in the brain and two in the spine. The brain lesion was in the occipital region. The spine lesions were thoracic intramedullary and sacral intradural. All cases were hypointense on T2-weighted imaging. Gross total resection was achieved for all lesions without adjuvant therapy. To date, the brain lesion recurred 15 months after surgery.

CONCLUSIONS

MS is a rare and distinct entity rather than a variant of schwannoma, and it poses both diagnostic and management dilemmas. Although MS has characteristic MRI features, including T1 and T2 shortening, the preoperative diagnosis is always challenging. Accurate diagnosis is crucial for management planning, including long-term follow-up exams to assess for recurrence and metastasis.

Melanotic Schwannoma of the Vagina: A Report of a Very Rare Tumor and Review of the Literature

Melanotic schwannoma (MS) is a rare nerve sheath tumor with fewer than 200 cases reported. MS has uncertain malignant potential and comprises 1% of all nerve sheath tumors with a predilection for the spinal nerve roots. An even rarer location for this tumor is the vagina. Up to 55% of MSs that contain psammoma bodies are associated with the Carney complex, an autosomal dominant syndrome. Criteria for malignancy in MS are still not well established and long term follow-up of patients is recommended. A 26-year-old woman presented with a bleeding vaginal tumor which was diagnosed as MS following excision. The clinical, histopathological, and immunohistochemical features of this tumor are discussed.

Malignant Melanotic Schwannian Tumor Presenting with Spinal Cord Infarction Due to Occlusion of the Artery of Adamkiewicz: Case Report and Review of the Literature

BACKGROUND

Malignant melanotic schwannian tumors (MMSTs) are rare peripheral nerve sheath tumors that typically exhibit benign clinical presentation and histopathology but malignant long-term behavior.

CASE DESCRIPTION

We report a case of a 22-year-old male with a T9-11 MMST who presented with acute paraplegia and complete loss of sacral function. Despite emergent decompression, he did not recover motor, sensory or bladder function, although bowel function did normalize.

CONCLUSIONS

The anatomic location and rapid presentation of permanent deficits are suggestive of infarction of the spinal cord supplied by the artery of Adamkiewicz, a rare presentation of this disorder and of spinal schwannomas in general.

Pigmented Melanotic Schwannoma of the Neck: Report of 2 Cases and Review of the Literature

BACKGROUND:

Melanotic schwannoma is a rare tumor with indeterminate biologic behavior and varying treatment recommendations.

METHODS:

We report 2 cases of pigmented melanotic schwannoma of the head and neck and perform literature review. The pathologic and immunohistochemical characteristics of melanotic schwannoma are reviewed.

RESULTS:

Two cases of melanotic schwannoma are presented. Both cases underwent surgical resection with one patient receiving adjuvant radiation therapy.

CONCLUSIONS:

Melanotic schwannoma is a rare nerve sheath tumor that is frequently mistaken for malignant melanoma. We describe 2 cases of pigmented melanotic schwannoma of the head and neck with different presentations and review the histopathological and immunohistochemical features.

Intramedullary melanotic schwannoma of the cervical spine: A case report and literature review

Intramedullary melanotic schwannomas (IMS) are rare lesions, with only 8 cases reported in the literature to date. We herein describe the case of a 40-year-old male patient with an IMS of the cervical cord, which, to the best of our knowledge, is the ninth reported case of IMS, and review the relevant literature. The patient presented with numbness of the left arm that gradually worsened over a period of 4 months. Magnetic resonance imaging (MRI) of the cervical spine with gadolinium enhancement revealed an intramedullary lesion at the level of C1-C2. The mass was T1 hyperintense, T2 hypointense and homogeneously enhanced. During surgery, an intramedullary dark gray lesion was identified and was partially removed. The left arm numbness partially subsided 2 weeks after surgery. Although rare, IMS is associated with characteristic MRI findings (T1 hyperintensity, T2 hypointensity and homogeneous enhancement) and MRI is the preferred method for evaluating lesions of the spinal cord. Correct diagnosis is crucial for management planning; therefore, immunohistochemical examination is required. In addition, IMS cases must be closely followed up, particularly when the mass cannot be completely resected.

Pathology of Melanotic Schwannoma

CONTEXT.—

Melanotic schwannoma (MS) is a nerve sheath tumor with a uniform composition of variably melanin-producing Schwann cells and metastatic potential. The MS is an uncommon neoplasm, accounting for less than 1% of all nerve sheath tumors, with a predilection for spinal nerve involvement. Microscopically, the tumors are characterized by spindle and epithelioid cells arranged in interlacing fascicles, with marked accumulation of melanin in neoplastic cells and associated melanophages. The MSs are frequently associated with Carney complex, showing features of psammoma bodies and adipose-like cells. Strict criteria of malignancy in MS are not well developed, although a combination of worrisome histologic features (large, vesicular nuclei, with macronucleoli, brisk mitotic activity, and necrosis) raises concern for aggressive behavior.

OBJECTIVE.—

To review the current status of the MS literature, discussing putative etiology, histopathology, current genetics, and differential diagnoses, including overlap with other pigmented tumors.

DATA SOURCES.—

Search of PubMed (National Center for Biotechnology Information, Bethesda, Maryland) and the authors' own experiences.

CONCLUSIONS.—

The occurrence of MS at several unusual anatomic sites and its spectrum of morphologic patterns can result in significant diagnostic difficulty, and correct diagnosis is particularly important because of its high tendency to recur locally and to metastasize, which highlights the importance of diagnostic recognition, ancillary molecular genetic testing, and close clinical follow-up of patients with MS.

Intracranial melanotic schwannomas: a rare variant with unusual adherent features

Intracranial melanotic schwannomas (IMSch) are extremely rare nerve sheath tumors with features of Schwann cells that produce melanin. After a thorough review of the available literature since 1967, we report not only the 20th case of IMSch but a comprehensive modern-era analysis of radiographic and histological key-points to be considered when diagnosing and treating patients with this rare known entity. This is the case of a 43 years-old woman who presented with severe headaches 9 years ago (2008). At that time, MRI of the brain showed a 1.5 × 1.4 cm lesion at the level of the left cerebellar peduncle without any evidence of edema, mass effect or hydrocephalus. Given that the patient was neurologically intact, a conservative management with serial MRIs was recommended. Patient stopped following up due to the absence of symptoms. Over the course of the past year, patient noted mild left sided hearing loss and facial weakness, as well as some balance instability that progressed over the last 3 months. Given the presentation and progression of these signs and symptoms, a new MRI was performed in which considerable growth of the lesion was identified, measuring 2.5 × 2.8 × 2.6 cm with mass effect on the pons and the inferior fourth ventricle. She underwent a far lateral approach without a C1 hemilaminectomy for the resection of this lesion. Final pathology was consistent with a non-psammomatous melanotic schwannoma (NPMS) with areas of necrosis. Besides this case, only two other cases of IMSch with findings of necrosis have been reported in the literature, all of them reporting a subtotal resection. Evaluation of all previously reported cases of IMSch shows a male prevalence with a 1.6:1 male to female ratio. IMSch is radiographically T2 hypointense and can be differentiated from Schwannomas that are classically T2 hyperintense. In this case, only a subtotal resection was feasible due to the tumor's overwhelming inherent attachment to vital structures such as cranial nerves (CN), brainstem, and vasculature. While MSch is considered histologically benign, several factors including localization, surrounding structures, the rate of growth, tumor volume resection and histological necrosis should be considered in determining prognosis and further adjuvant treatment planning.

Invasive intramedullary melanotic schwannoma: case report and review of the literature

PURPOSE

Melanotic schwannoma (MS) is rare, accounting for less than 1% of primary peripheral nerve sheath tumors, and most often occurs in the paraspinal nerve roots. Intramedullary MS is exceedingly rare, and to the best of our knowledge, only nine cases have been reported in literature.

METHODS AND RESULTS

We present a 47-year-old male, who underwent excision of thoracic intraspinal space-occupying lesion 6 years ago, as the 10th known case to date of intradural intramedullary MS that had a more invasive growth pattern than those reported before, and we review the diagnosis, clinicopathologic features, treatment and prognosis of intramedullary MS.

CONCLUSIONS

Intramedullary MS' behavior is unpredictable and can have an aggressive clinical course such as recurrence and metastasis.

Rexin-G®, a tumor-targeted retrovector for malignant peripheral nerve sheath tumor: A case report

Soft tissue sarcoma is a rare neoplasm of mesenchymal origin, accounting for only ~1% of all adult cancers and consisting of 75 histological subtypes. In the present report, the unique case of a 14 year-old female with metastatic malignant peripheral nerve sheath tumor (formerly, malignant melanotic schwannoma) of the parotid gland, who experienced a durable response and sustained tumor control with Rexin-G^®, a tumor-targeted retroviral expression vector encoding an anti-cyclin G1 construct, is described. Post-parotidectomy, and prior to the administration of Rexin-G^®, the patient received various chemotherapy regimens, including doxorubicin, ifosfamide, temozolomide, sorafenib, and an immunological therapy with interleukin-2, which only resulted in the further progression of lung metastases. The patient subsequently participated in a Phase 1/2 gene therapy study, during which she received intravenous Rexin-G^® as monotherapy for two years with minimal drug-associated adverse events. Currently, the patient has no evidence of active disease 9 years after commencing the Rexin-G^® treatment, and with no additional anti-cancer therapy. In conclusion, Rexin-G^® may be a viable therapeutic option for malignant peripheral nerve sheath tumors, and should be further investigated in prospective histology-specific clinical trials for this type, and possibly other types, of chemotherapy-resistant sarcoma.

A Rare Case of Aggressive Melanotic Schwannoma Occurred in Spinal Nerve of a 59-Year-Old Male

Melanotic schwannoma (MS) is a rare variant of nerve sheath neoplasm that shows ultrastructural and immunophenotypical features of Schwann cells but also has cytoplasmic melanosomes and is reactive for melanocytic markers as well. Unlike conventional schwannoma, which is totally benign, MS has an unpredictable prognosis and is thought to have low-malignant potential. Herein, we present a rare case of recurrent MS in lumbar spine of a 59-year-old male.

Clinical outcomes following resection of giant spinal schwannomas: a case series of 32 patients

OBJECTIVE

The objective of this study was to review clinical outcomes following resection of giant spinal schwannomas.

METHODS

The authors conducted a retrospective review of a case series of patients with giant spinal schwannomas at a tertiary cancer hospital.

RESULTS

Thirty-two patients with giant spinal schwannomas underwent surgery between September 1998 and May 2013. Tumor size ranged from 2.5 cm to 14.6 cm with a median size of 5.8 cm. There were 9 females (28.1%) and 23 males (71.9%), and the median age was 47 years (range 23–83 years). The median follow-up duration was 36.0 months (range 12.2–132.4 months). Three patients (9.4%) experienced recurrence and required further treatment. All recurrences developed following subtotal resection (STR) of cellular or melanotic schwannoma. There were 3 melanotic (9.4%) and 6 cellular (18.8%) schwannomas included in this study. Among these histological variants, a 33.3% recurrence rate was noted. In 1 case of melanotic schwannoma, malignant transformation occurred. No recurrence occurred following gross-total resection (GTR) or when a fibrous capsule remained due to its adherence to functional nerve roots.

CONCLUSIONS

Resection is the treatment of choice for symptomatic or growing giant schwannomas, frequently requiring anterior or combined approaches, with the goals of symptom relief and prevention of recurrence. In this series, tumors that underwent GTR, or where only capsule remained, did not recur. Only melanotic and cellular schwannomas that underwent STR recurred.

Pitfalls and uncertain prognosis in pathological diagnosis of psammomatous melanotic schwannoma

A 20-year-old woman presenting with a pelvic mass identified as a psammomatous melanotic schwannoma (PMS) with atypical histological features was later found to have family history of cardiac myxomas consistent with Carney's complex. The BRAF V600E mutation was absent in the tumor.

Pigmented Lesions of the Nervous System and the Neural Crest: Lessons From Embryology

Neurosurgeons encounter a number of pigmented tumors of the central nervous system in a variety of locations, including primary central nervous system melanoma, blue nevus of the spinal cord, and melanotic schwannoma. When examined through the lens of embryology, pigmented lesions share a unifying connection: They occur in structures that are neural crest cell derivatives. Here, we review the important progress made in the embryology of neural crest cells, present 3 cases of pigmented tumors of the nervous system, and discuss these clinical entities in the context of the development of melanoblasts. Pigmented lesions of the nervous system arise along neural crest cell migration routes and from neural crest-derived precursors. Awareness of the evolutionary clues of vertebrate pigmentation by the neurosurgical and neuro-oncological community at large is valuable for identifying pathogenic or therapeutic targets and for designing future research on nervous system pigmented lesions. When encountering such a lesion, clinicians should be aware of the embryological basis to direct additional evaluation, including genetic testing, and to work with the scientific community in better understanding these lesions and their relationship to neural crest developmental biology.

Non psammomatous melanocytic schwannoma presenting as a subcutaneous nodule: A rare presentation of a rare lesion

Melanocytic schwannoma (MS) is an extremely rare soft tissue tumor accounting for less than 1% of all primitive nerve sheath tumors, with a predilection for spinal nerve involvement. To date, only 20 cases of cutaneous/subcutaneous MS have been described in literature. Here, we describe a case of MS presenting as a subcutaneous nodule in a 22-year-old male in right thigh. On examination, the nodule measured 2.5 × 2.0 × 1.5 cm with overlying skin showing a bluish hue and an ulcer. With a preoperative diagnosis of hemangioma, the patient was taken up for wide local excision and was diagnosed as a case of non psammomatous melanocytic schwannoma based on clinical, histological, and immunohistochemical studies. Immunohistochemistry revealed positivity with S-100, HMB-45, and Melan A with pericellular Laminin positivity. Carney's syndrome was ruled out. MS needs to be differentiated from other pigmented lesions like pigmented neurofibroma, Bednar tumor, cellular blue neavus, and especially malignant melanoma, which has an obvious ominous prognosis. Since MS can show unpredictable behavior especially in absence of overt malignant features, a long term follow up with or without radiotherapy is recommended.

Melanotic schwannoma of the L5 root

Melanotic neoplasm of the central nervous system is rare and the majority of them are metastatic. Melanotic schwannoma (MS) is an unusual variant of nerve sheath neoplasm accounting for less than 1% of primary nerve sheath tumors. A case involving a 36-year-old man with MS at the L5 root is presented. Surgery, differential diagnosis, radiology, histology, and treatment of this rare entity are discussed.

Melanotic schwannoma: an 11-year case series

Melanotic or melanocytic schwannoma is a rare tumour usually involving spinal nerve roots but can also present at other anatomical locations. Although there are less than 200 cases reported, melanotic schwannomas can have distinctive imaging features but there is limited recent literature on its often characteristic radiological appearances. Recent publication of the largest case series thus far has suggested melanotic schwannoma to be a separate entity to other schwannomata and that its reclassification to a malignant lesion be under consideration. We present a case series over an 11-year period to highlight salient imaging features with reference to the current concerns regarding its malignant potential.

Consistent copy number changes and recurrent PRKAR1A mutations distinguish Melanotic Schwannomas from Melanomas: SNP-array and next generation sequencing analysis

Melanotic Schwannomas (MS) are rare tumors that share histological features with melanocytic tumors and schwannomas. However, their genetics are poorly understood. To elucidate the genetic characteristics of MS, we performed genome-wide studies in a series of cases. Twelve MS cases were available for the study. Genomic DNAs extracted from formalin-fixed paraffin embedded tumor tissues were subjected to copy number (CN) and allelic imbalance (AI) analysis by Single Nucleotide Polymorphism (SNP)-array and screened for mutations in coding exons of 341 key cancer-associated genes using a hybrid capture-based next-generation sequencing (NGS) assay. Sanger sequencing was used to further verify recurrent mutations detected by NGS study. SNP-array analysis revealed remarkably stereotypic chromosomal abnormalities in MS. Hypodiploidy was common, typically involving monosomies of chromosomes 1, 2, and 17. All 12 samples showed mutations in PRKAR1A gene, including 2 cases with 2 mutations each. The 14 mutations were scattered across PRKAR1A, and most were inactivating mutations. AI on 17q, presenting as loss of heterozygosity with or without CN losses, combined with a PRKAR1A mutation was observed in 9/12 MS cases. The remaining 3 cases included the two samples harboring two mutations in PRKAR1A. MS exhibits a stereotypic pattern of chromosomal losses. In contrast, melanomas are typically characterized by the presence of multiple CN aberrations, without demonstrable differences in the frequency of losses and gains. Inactivation of both alleles of PRKAR1A by "two hits" observed in almost all cases underscores the central role of PRKAR1A in the pathogenesis of this neoplasm. © 2015 Wiley Periodicals, Inc.

Intraspinal psammomatous melanotic schwannoma not associated with Carney complex: case report

The authors present a case of intraspinal malignant psammomatous melanotic schwannoma (PMS) not associated with Carney complex and review all reported cases not associated with this syndrome. The focus of this review paper is on the characteristics of the malignant progression of PMS. A 54-year-old man had a history of squamous cell carcinoma of the neck and tonsillar carcinoma. The patient's serial CT scanning study showed a mass in the left C-5 foramen. On presentation he was neurologically intact. After 18 months, the patient developed radiating pain down the left arm with decreased sensation. MRI of the cervical spine showed an enhancing 2.1 × 1.5 × 1.9-cm mass in the left C5-6 foramen. A C5-6 hemilaminectomy was performed with gross-total removal of the tumor. At 3 months postoperatively, the patient developed new-onset pain and weakness. MRI showed a dumbbell-shaped mass in the left C-7 foramen. MRI of the pelvis showed a 1.4 × 1.0-cm lesion on the right ischium and a 1.1 × 2.8-cm lesion on the right inferior pubic ramus. Anterior cervical discectomy of C5-6 and C6-7 with corpectomy of C-6 with subtotal resection of the tumor was completed. PMS should not be considered a benign tumor because in 41.1% of patients, including the patient in this report, the tumor progresses to malignancy. Long-term follow-up is needed in these patients. New surgical treatment plans should be considered.