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| IMAGES IN ACADEMIC MEDICINE |
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| Year : 2015 | Volume
: 1
| Issue : 1 | Page : 45-48 |
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Malignant peripheral nerve sheath tumor
Yaoyun Sarah Shen1, Heidi H Hon2, Thomas J Papadimos3, Stanislaw P Stawicki2, Sherwin P Schrag1
1 Department of Surgery, Jersey City Medical Center-Barnabas Health, Jersey City, New Jersey, USA
2 Department of Surgery, St. Luke's University Health Network, Bethlehem, Pennsylvania, USA
3 Department of Anesthesiology, The Ohio State University College of Medicine, Columbus, Ohio, USA
| Date of Web Publication | 29-Dec-2015 |
Correspondence Address:
Stanislaw P Stawicki
Department of Surgery, St. Luke's University Health Network, 801 Ostrum Street, Bethlehem, Pennsylvania
USA
 Source of Support: None, Conflict of Interest: None  | Check |
Type 1 neurofibromatosis (NF1) is also known as von Recklingausen's disease. Among patients affected by NF1, fast-growing plexiform type neurofibromas have a high rate of malignant transformation and need to be distinguished from benign plexiform neurofibromas. Here, we describe an emergent case presentation with rapid transformation of neurofibromatosis into a malignant peripheral nerve sheath tumor in a male patient in his early 20's, who was admitted with a 4-day history of urinary retention, pelvic “fullness,” and lower back pain. Highlighted are computed tomography imaging characteristics of malignant peripheral nerve sheath tumor, exemplified by a large retroperitoneal/pelvic mass compressing the bladder and both ureters, resulting in bilateral hydronephrosis and urinary retention, and prompting urgent surgical resection. Associated MRI images and an intraoperative photograph are also presented.
The following core competencies are addressed in this article: Patient care, Medical knowledge, Systems-based practice Keywords: Computed tomography, magnetic resonance imaging, malignant peripheral nerve sheath tumor, neurofibromatosis type 1, surgical emergency, urinary retention
How to cite this article:
Shen YS, Hon HH, Papadimos TJ, Stawicki SP, Schrag SP. Malignant peripheral nerve sheath tumor. Int J Acad Med 2015;1:45-8 |
| Introduction | |  |
Type 1 neurofibromatosis (NF1), or von Recklinghausen's disease, has been closely linked with neurofibromatosis 2 (NF2). They are both autosomal dominant disorders with NF1 having an incidence rate of about 1 in 3500–1 in 5000.[1] Both may be associated with de novo mutations and tumor formation.[2] NF1 is more common that NF2 and primarily affects the skin and peripheral nervous system, whereas NF2 is seen less frequently, with few skin manifestations, and serious malignancy resulting rarely.[2] NF1 gene codes for neurofibromin (chromosome 17q11.2), which is a negative regulator of the RAS signal transduction mechanism.[3],[4],[5],[6] Neurofibromas found in NF1 can be dermal or plexiform, with plexiform neurofibromas having a greater propensity for transformation into malignant peripheral nerve sheath tumors (MPNSTs). These lesions usually emerge in late adolescence and can increase during pregnancy.[2] Here, we present a case synopsis with radiographic and clinical images from an emergent presentation of such transformation of neurofibromatosis into an MPNST. The patient required urgent surgical intervention due to compressive symptoms in the pelvis.
| Case Synopsis | | |
A male patient in his early 20's with known NF1 presented to the emergency department with complaints of difficulty urinating and associated “pelvic fullness” for 4 days. The patient recalled intermittent urinary retention, constipation, and lower back pain that had been progressively worsening over the preceding 10 months. His initial exam was remarkable for lower abdominal pain, and the presence of cutaneous café-au-lait spots [Figure 1]. His family history was significant for two other family members with NF1. His surgical history included resection of several painful subcutaneous neurofibromas. | Figure 1:Cutaneous manifestations of type 1 neurofibromatosis. Café-au-lait spots noted on the patient's right lateral chest, right forearm, and central neck
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A postvoid residual of 1500 mL of clear urine confirmed urinary retention. Pertinent laboratory results included elevated creatinine of 1.5 mg/dL and mild leukocytosis of 12,500 cells/μL. Computed tomography of the abdomen [Figure 2] revealed a large posterior pelvic mass that was compressing the distal ureters and causing bilateral hydronephrosis. The mass was suspected to be a largely, degenerated neurofibroma, possibly malignant. | Figure 2:Computed tomography shows a large pelvic mass (arrows) compressing the urinary bladder, the rectum, and bilateral ureters
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Subsequent magnetic resonance imaging [MRI] of the cervical, thoracic, and lumbar spines revealed extensive neurofibromas without intradural extension or cord compression. MRI of the pelvis revealed extensive neurofibromas along the lower intercostal nerves, psoas and iliopsoas muscles, and sciatic nerves bilaterally, many of which were plexiform [Figure 3]. A large round mass measuring approximately 11 cm × 10 cm × 11 cm is seen in [Figure 3] within the posterior pelvis, with thick nodular peripheral enhancement and heterogeneous central necrosis. The mass displaced the bladder anteriorly and superiorly, compressing distal ureters, and causing bilateral hydronephrosis. The bladder wall was thickened. Innumerable smaller neurofibromas were scattered throughout the subcutaneous fat of the abdominopelvic walls, as well as within the abdominal and pelvic cavities. | Figure 3:Magnetic resonance imaging of the lesion. In addition to the large, centrally located mass, multiple neurofibromas can be seen bilaterally, mainly superior to the mass (e.g., clustered grape-like round/oval densities). Of note, neurofibromas usually show heterogeneous enhancement, whereas schwannomas tend to be more homogeneous. Furthermore, note the so-called “target sign” – A central area of lower intensity surrounded by higher intensity material on T2 images – often seen in plexiform neuromas
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A decision was made to excise the mass to relieve acute clinical symptoms. Intraoperatively, the mass was found to be deep in the pelvis, richly vascular and densely attached to the mesorectum anteriorly and sacrum posteriorly, with areas of necrosis and associated fluid collection. Postoperatively, the patient made an unremarkable recovery and was discharged 2 days after the operation. On gross examination, the mass had a pink tan capsule, weighed 439 g, and measured 14 cm × 11 cm × 9.5 cm [Figure 4]. | Figure 4:Photograph of the resected pelvic mass. Microscopic evaluation of the resected mass (images not shown) revealed high-grade sarcoma, consistent with malignant peripheral nerve sheath tumor
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| Discussion | | |
The diagnostic criteria for NF type 1 were established and differentiated from NF type 2 in the 1980's.[7] Due to the variability of expression, patients need to exhibit a minimum of 2 out of 7 criteria to be diagnosed with NF1 [Table 1].[8] The current patient exhibited at least 3 out of 7 diagnostic criteria. On physical examination, café-au-lait macules were visible [Figure 1]. He had numerous neurofibromas and plexiform neurofibromas on imaging. He also had two first-degree relatives with NF1.
Dermal neurofibromas are associated with a single peripheral nerve and can be cutaneous, subcutaneous, or deep nodular depending on their location. Plexiform neurofibromas involve multiple nerve bundles and have greater potential for transformation into MPNST. MPNST comprises roughly 5–10% of soft tissue sarcomas.[9] Up to 29% of patients with NF1 suffer from MPNST and 50–60% of MPNST occur in patients with NF1.[10] Five-year survival rate of MPNST is approximately 50%.[11] In the current case, the primary tumor was found to be a high-grade sarcoma and measured 14 cm × 11 cm × 9.5 cm. Both of these findings are poor prognostic indicators.[11]
The treatment for MPNST is mainly surgical as these tumors are relatively less responsive to chemotherapy and radiation.[11],[12] The 5-year local recurrence rate is approximately 27% with distant metastases present in nearly 30% of cases at 10 years.[13] Most recurrences (approximately 80%) happen within 2 years of resection.[13] Trunk/extremity tumor location, higher grade, and larger tumors have the highest local recurrence rate.[10],[13] The most common site of distant MPNST spread is the lung.[13]
It is important for patients to understand that NF1 is associated with a 50% risk of being inherited by one's offspring, and that children at risk should undergo an annual examination and continued education about their disease, which includes visual testing until age seven along with examination of skin, spine, blood pressure, weight, height, and circumference of the head.[2]
| Conclusions | | |
NF1 may be associated with fast-growing plexiform neurofibromas that have a high rate of malignant transformation. Vigilance is necessary on the part of the medical practitioner in the follow-up of individuals at risk. Malignant peripheral neural sheath tumors comprise roughly 5–10% of soft tissue sarcomas and are significantly associated with NF1. Surgery remains the most effective therapeutic modality for MPNST with radiation/chemotherapy playing an adjunctive role. Following resection, about 80% of recurrences are detected within 2 years. Approximately, half of the patients with MPNST die within 5 years of diagnosis.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1]
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