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

The "Pigmented Side" of Nerve Sheaths: Malignant Melanotic Nerve Sheath Tumor

Malignant melanotic nerve sheath tumor (MMNST) represents a highly aggressive neoplasm arising both in peripheral and cranial nerves. It accounts for < 1% of all nerve sheath tumors, but the real incidence may not be well defined yet because of the evolution of its nomenclature. To date, it is considered a distinct tumor type, no longer as the pigmented variant of schwannoma, with a different clinical course and biological behavior. MMNSTs exhibit a specific genetic hallmark related to the PRKAR1A gene, which explains the major incidence in Carney Complex-affected patients. One of the more frequent localizations is the paravertebral region, where it poses diagnostic concerns with both primary tumors arising from soft tissues and the meningeal covering, as well as metastatic ones (ie, melanoma). Herein we present a patient with an MMNST accompanied by the main clinical, radiological, histopathological, and molecular findings, stressing the need for a multidisciplinary diagnostic approach. To the best of our knowledge, this is the first report of proton beam therapy for MMNST. We also performed a literature review to collect and compare the more recent data in English literature and to highlight the "keep-in-mind" concepts to apply in a multidisciplinary diagnostic algorithm, with a focus on histopathology and related pitfalls.

Rare giant retroperitoneal melanotic schwannoma: a case report and literature review

Background

Melanotic schwannoma (MS), a rare variant of peripheral nerve sheath tumor, is especially infrequent when originating from the peritoneum. Its definitive diagnosis relies on postoperative histopathological examination and immunohistochemical analysis, while preoperative diagnosis is difficult.

Case presentation

In the present study, we reported a rare case of giant MS in the retroperitoneum, which was previously misdiagnosed before surgery. However, intraoperative exploration revealed it was retroperitoneal tumor. The tumor had invaded the abdominal aorta and bilateral common illiac artery walls. A surgical resection was subsequently executed, and postoperative histopathological examination confirmed it as a MS.

Conclusion

The incidence of peritoneal MS is extremely rare, and surgical resection remains the preferred treatment modality. Given the absence of established guidelines for postoperative adjuvant therapy, long-term follow-up becomes imperative to accumulate valuable clinical expertise.

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.

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.

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.

Retroperitoneal Recurrence of Melanotic Schwannoma on 18F-FDG PET/CT

ABSTRACT

Melanotic schwannoma is an uncommon nerve sheath neoplasm. Only 10% of melanotic schwannoma are malignant whereas metastases from melanotic schwannoma are much less common. Hereby we present FDG PET/CT findings of recurrent left retroperitoneal melanotic schwannoma with widespread metastases in a 50-year-old man.

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.

Extramedullary melanotic schwannoma recurrence in the cervical vertebral arch: a case report and review of the literature

Melanotic schwannoma (MS), a slowly growing nerve sheath tumor, is not a purely benign tumor. MS accounts for less than 1% of all nerve sheath tumors. We herein describe a rare case of MS and present a literature review focusing on the treatment of this disease. Twelve years before presentation at our hospital, a 41-year-old woman was examined because of an 8-month history of neck pain and 6-month history of upper extremity numbness and weakness. She underwent surgery to remove a tumor, and the pathological examination confirmed a diagnosis of MS. Twelve years later, at 53 years of age, the patient presented to our hospital with a 2-year history of neck pain and upper extremity numbness and weakness. Posterior cervical tumor resection was performed along with posterior cervical laminectomy, decompression and intraspinal space-occupying internal fixation, and radiotherapy. MS recurrence was confirmed. No tumor recurrence or metastasis was found after 7 months of follow-up. Recurrence of MS is rare, and its diagnosis depends on pathological features. Radical excision is the primary treatment for MS. Incomplete resection of MS is a risk factor for postoperative recurrence and metastasis. Furthermore, postoperative adjuvant radiotherapy should be performed to prevent recurrence and metastasis of MS.

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.

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.

Intraosseous Melanotic Schwannoma in the Sacrum Mimicking Primary Bone Tumor

Primary tumors of sacrum are rarely seen, and the differential diagnosis is extensive, such as chordomas, giant cell tumors, and schwannomas. Sacral intraosseous schwannomas (IOSs) are very rare and encompass approximately 1%–5% of all spinal schwannomas. Melanotic schwannomas (MSs) are categorized as an unusual variant of benign schwannomas; however, they sometimes follow a malignant course. The authors present a case of MS with intraosseous extension into sacrum in a 48-year-old male arising from the left S2 nerve root. Magnetic resonance imaging (MRI) and computed tomography (CT) scan demonstrated a destructive mass in the sacrum. He was made a diagnosis with MS by 18F-fluoro-deoxy-glucose positron-emission-tomography (¹⁸F-FDG PET) and open biopsy. The tumor was blackish-colored and vascular-rich fragile tumor covered by fibrous capsule. The floor of the tumor was not encapsulated and invading into the sacral bone. Total removal of the tumor together with the left S2 nerve of origin via posterior approach was achieved. The patient made dramatic recovery of neurological symptoms and tumor recurrence is not seen for 6-month follow-up period. MS is a benign tumor with potential for aggressive behavior and capacity to metastasize. Therefore, total removal of the tumor and careful postoperative follow-up are recommended. Postoperative spinopelvic stability also needs to be taken into consideration. The authors discuss our successful management with a focus on diagnostic process, surgical planning, and histological consideration to provide the most up-to-date guidance on managing this challenging tumor.

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.

Schwannoma originating from the common iliac artery: a case report

Schwannomas of the large blood vessels are extremely rare, and tumors adjacent to major vessels may not be considered to originate from the vessels. There have been no previous reports of schwannomas of the common iliac artery. We report on a 57-year-old woman who presented with a mass in the left retroperitoneum. Computed tomography showed a mass abutting and adhering to the left common iliac artery. A portion of the artery was resected together with the mass and vascular reconstruction was carried out. The histological diagnosis was a schwannoma arising in the left common iliac artery. Despite its rarity, a schwannoma of a large artery should be considered as a differential diagnosis in patients with a retroperitoneal mass adjacent to a major vessel. Awareness of this entity might avoid profuse bleeding and enable surgeons to prepare for vascular interposition.

Melanotic Schwannomas Are Rarely Seen Pigmented Tumors with Unpredictable Prognosis and Challenging Diagnosis

Melanotic Schwannoma (MS) is rarely seen and potentially malignant neoplasm that is categorized as a variant of Schwannoma. MS most frequently involves intracranial structures followed by posterior nerve roots in the spinal canal. Approximately 50% of the cases with MS have psammomatous calcifications and this type of MS is related to Carney complex with autosomal dominant inheritance. Most cases of MS are benign, though 10% of them are malignant with metastatic potential. MS mimics melanoma and the differential diagnosis should be made excluding other melanin producing neoplasms especially melanoma. Case 1. A 42-year-old hypertensive male presented for checkup. He had a well-defined extraspinal oval lesion measuring 3.5 × 2.5 cm near right adrenal. Case 2. A 22-year-old female presented with neurofibromatosis-2, bilateral acoustic schwannomas and café au lait lesions on sacrococcygeal region. She had an intradural extramedullary lesion measuring 6.1 × 2.0 cm at L1-2 level. MS is a rare neoplasm composed of Schwann cells and melanin pigment. These tumors are usually benign but they may become aggressive. The biologic behavior of MS is difficult to predict; the patients have to be followed up for a longer period due to its malignant potential.