Neuromuscular choristoma-associated desmoid-type fibromatosis of the brachial plexus: Additional evidence to support a nerve-driven mechanism.

BACKGROUND: We have recently described circumferential nerve involvement of neuromuscular choristoma associated with desmoid-type fibromatosis (NMC-DTF) in cases involving the sciatic nerve, supporting a nerve-derived mechanism for the DTF. We wondered whether a similar growth pattern occurs in cases involving the brachial plexus (BP). METHODS: We reviewed all available magnetic resonance (MR) imaging in patients diagnosed at our institution with NMC or NMC-DTF of the BP. We also performed a literature search of patients with NMC or NMC-DTF of the BP. RESULTS: In our clinical records, four patients with NMC of the BP were identified, and three developed NMC-DTF. All three patients had MR imaging evidence of circumferential encasement of the BP. In the literature, we identified 15 cases of NMC of the BP, of which 12 had identified NMC-DTF. Four published cases included MR images, and only two were of sufficient quality for review. The single provided image in both cases demonstrated a similar pattern of circumferential encasement of the BP by the NMC-DTF. One additional case report was published without MR images but described circumferential involvement in the surgical findings. One unpublished case of NMC-DTF of the BP from an international radiology meeting also had this circumferential pattern pattern on MRI. CONCLUSIONS: The MRI findings of circumferential nerve involvement in patients with NMC-DTF of the BP are similar to our previously reported data in patients with NMC-DTF of the sciatic nerve, providing further imaging-based support of a nerve-driven mechanism. Clinical implications are presented based on the proposed pathogenetic mechanism.

Neuromuscular choristoma and circumferential nerve territory desmoid-type fibromatosis: imaging findings supporting a nerve-driven mechanism.

OBJECTIVE: Neuromuscular choristoma (NMC) is a rare developmental malformation of peripheral nerve that is frequently associated with the development of a desmoid-type fibromatosis (DTF). Both NMC and NMC-DTF typically contain pathogenic CTNNB1 mutations and NMC-DTF develop only within the NMC-affected nerve territory. The authors aimed to determine if there is a nerve-driven mechanism involved in the formation of NMC-DTF from the underlying NMC-affected nerve. METHODS: Retrospective review was performed for patients evaluated in the authors' institution with a diagnosis of NMC-DTF in the sciatic nerve (or lumbosacral plexus). MRI and FDG PET/CT studies were reviewed to determine the specific relationship and configuration of NMC and DTF lesions along the sciatic nerve. RESULTS: Ten patients were identified with sciatic nerve NMC and NMC-DTF involving the lumbosacral plexus, sciatic nerve, or sciatic nerve branches. All primary NMC-DTF lesions were located in the sciatic nerve territory. Eight cases of NMC-DTF demonstrated circumferential encasement of the sciatic nerve, and one abutted the sciatic nerve. One patient had a primary DTF remote from the sciatic nerve, but subsequently developed multifocal DTF within the NMC nerve territory, including 2 satellite DTFs that circumferentially encased the parent nerve. Five patients had a total of 8 satellite DTFs, 4 of which abutted the parent nerve and 3 that circumferentially involved the parent nerve. CONCLUSIONS: Based on clinical and radiological data, a novel mechanism of NMC-DTF development from soft tissues innervated by NMC-affected nerve segments is proposed, reflecting their shared molecular genetic alteration. The authors believe the DTF develops outward from the NMC in a radial fashion or it arises in the NMC and wraps around it as it grows. In either scenario, NMC-DTF develops directly from the nerve, likely arising from (myo)fibroblasts within the stromal microenvironment of the NMC and grows outward into the surrounding soft tissues. Clinical implications for patient diagnosis and treatment are presented based on the proposed pathogenetic mechanism.

Tibial intraneural ganglion cysts at the superior tibiofibular joint treated with joint resection alone: a proof of concept.

BACKGROUND: Intraneural ganglion cysts involving the tibial nerve are rare. Recent evidence has supported an articular (synovial) theory to explain the joint-related origin of these cysts; however, optimal operative treatment for cysts originating from the STFJ remains poorly understood. Therefore, we present a novel strategy: addressing the joint itself without addressing the articular branch and/or the cyst. METHODS: Records of patients with tibial intraneural ganglion cysts with a connection to the STFJ who were treated with a joint resection alone at a single academic institution were reviewed. The clinicoradiographic features, operative intervention, and postoperative course were recorded. RESULTS: We identified a consecutive series of 7 patients. These patients (4/7 male, 57%) were 43 (range 34-61) years of age and all presented with symptoms of neuropathy. The patients underwent resection of the synovial surfaces of the STFJ without disconnection of the articular branch or decompression of the cyst. Postoperatively, three patients regained partial motor function (43%, n=7), although four patients noted continued sensory abnormality (57%, 4/7). All six patients with postoperative MRIs had some evidence of regression of the cyst. CONCLUSIONS: This novel surgical technique serves as a proof of concept-highlighting the fact that treating the primary source (the joint origin) can be effective in eliminating the secondary problem (the cyst itself). While this study shows that this simplified approach can be employed in select cases, we believe that superior results (faster, fuller recovery) can be achieved with combinations of disconnecting the articular branch, decompressing the cyst, and/or resecting the joint.

The value of high-resolution imaging in an occult peroneal intraneural ganglion cyst: illustrative case.

BACKGROUND: Foot drop is a common complaint with a broad differential diagnosis making imaging a key part of the diagnostic workup. The authors present a patient with an occult peroneal intraneural ganglion cyst who underwent imaging with high-frequency ultrasound (US) and high-resolution magnetic resonance imaging (MRI) to highlight the role of such techniques in cases of peroneal neuropathy. OBSERVATIONS: Intraneural ganglion cysts are emerging as a common cause of common peroneal neuropathy. Imaging with US and MRI is a valuable tool used to illustrate the pertinent anatomy and identify the articular branch joint connection and cyst as part of the surgical planning and definitive management. LESSONS: Intraneural ganglion cysts can be small or nearly invisible and failure to appreciate the intraneural cyst can lead to symptom or cyst persistence or recurrence. High-resolution modalities can be useful in the diagnosis and surgical planning of difficult cases.

Malignant Peripheral Nerve Sheath Tumors Without Muscle Weakness at Presentation: An Analysis of an Underappreciated Combination.

OBJECTIVE: Patients with malignant peripheral nerve sheath tumors (MPNSTs) of major motor nerves typically present with muscle weakness and pain. We aimed to analyze and characterize patients with MPNSTs of major motor nerves but without muscle weakness at initial presentation. METHODS: We performed a retrospective search of MPNSTs in a major nerve evaluated and/or treated at our institution from 1994 to 2019. Patients with no muscle weakness and available magnetic resonance imaging were analyzed. Clinical materials and magnetic resonance imaging and positron emission tomography scans were reviewed for features of malignancy. This group of patients was compared with patients who presented with MPNSTs and muscle weakness. RESULTS: Of 26 patients with MPNSTs who presented with no muscle weakness, 21 (81%) had a positive family history for malignancy. Only 16 (62%) magnetic resonance imaging scans were highly suspicious for malignancy. All 7 available positron emission tomography scans were highly suspicious for malignancy. Patients who presented with muscle weakness (n = 36) were more likely to have paresthesias and a history of neurofibromatosis 1 or radiation to the MPNST location (P < 0.05). CONCLUSIONS: MPNSTs of major motor nerves without muscle weakness represent an underappreciated subset of cases that have potential treatment and outcome implications. These patients presented with fewer symptoms and had fewer risk factors than patients with muscle weakness. Positron emission tomography should be considered as an additional method to try to anticipate the diagnosis of an MPNST.

"Wrap-Around Sign" in Non-Hodgkin Lymphoma of the Spine: A Common yet Overlooked Imaging Feature?

BACKGROUND: Anecdotal cases of the so-called "wrap-around" appearance in non-Hodgkin lymphoma (NHL) of the spine exist in the medical literature. In this paper, we looked at the prevalence of this imaging feature in our institutional cases. MATERIALS AND METHODS: We screened our institutional database for biopsy-proven NHL. Our inclusion criteria were the histologically confirmed diagnosis of NHL involving any vertebra, available magnetic resonance imaging of the affected site, and a positive wrap-around sign. Exclusion criteria included lymphoma cases without the wrap-around sign and/or histology other than NHL. We subdivided the cases into 3 groups: 1) lymphoma wrapped around the vertebral body; 2) the posterior elements alone; or 3) both the vertebral body and posterior elements. RESULTS: Our search identified 147 cases of NHL in which a confirmatory biopsy at the primary tumor site was available. Of those, 23 cases fulfilled the inclusion criteria (16 men and 7 women with average age at diagnosis of 63.3 years), yielding prevalence of 15.6% in our series. Most commonly the lymphoma involved the vertebral body with or without some involvement of the posterior vertebral elements (n = 20, 86.9%), followed by posterior vertebral elements (n = 2, 8.7%). One remaining case (4.4%) had lymphoma involving the anterior vertebral body and posterior elements. CONCLUSIONS: Findings of our pilot study indicated that the wrap-around sign in cases of NHL could be helpful diagnostically. This sign may be frequently under-recognized, leading to potential for a diagnostic dilemma on imaging. Larger studies are necessary to obtain more precise information about the prevalence of the wrap-around sign.

Frequent CTNNB1 p.S45 Mutations and Aggressive Clinical Behavior in Neuromuscular Choristoma-Associated Fibromatosis.

BACKGROUND: Neuromuscular choristoma (NMC) is a peripheral nerve malformation frequently associated with a fibromatosis (NMC-DTF) that mimics sporadic desmoid-type fibromatosis (DTF). Sporadic DTF is often managed conservatively but its clinical behavior varies. CTNNB1 mutational subtypes in sporadic DTF have prognostic value. We have previously identified CTNNB1 mutations in NMC, and 3 paired NMC-DTF but the clinical behavior of NMC-DTF is poorly understood. OBJECTIVE: To evaluate patients with NMC-DTF to determine (1) CTNNB1 mutational subtypes in NMC-DTF, and (2) associated clinical behavior and response to treatment. METHODS: Retrospective review of clinical, imaging, and pathologic features of patients with NMC and NMC-DTF, and molecular testing for CTNNB1 mutations. RESULTS: Among 7 patients with NMC of the sciatic nerve (median age: 18 yr), NMC-DTF (mean size 10.7 cm) developed shortly following NMC biopsy (N = 5) or spontaneously (N = 2): 6 NMC-DTF had CTNNB1 p.S45X mutations and 1 NMC-DTF had a p.T41A mutation. All patients with CTNNB1-p.S45-mutated NMC-DTF developed local progression after wide local excision or active surveillance, including one distal metachronous NMC-DTF. No patient had spontaneous disease stabilization. Following adjuvant radiation or systemic therapy, disease stabilization was achieved in 4 (of 6) patients. One patient progressed on sorafenib treatment. CONCLUSION: NMC-DTF frequently contain CTNNB1 p.S45 mutations, behave aggressively, and require adjuvant therapies for disease stabilization. We now use imaging alone to diagnose NMC, and routinely surveille the NMC-affected nerve segment to identify early NMC-DTF. In contrast to sporadic DTF, earlier adoption of systemic therapeutic strategies may be required for optimal disease management of NMC-DTF.

Percutaneous image-guided biopsy in malignant peripheral nerve sheath tumors.

BACKGROUND: The decision to biopsy a peripheral nerve tumor is largely based on its presumed behavior and prognosis, determined by patient history, clinical exam, and radiologic characteristics. Percutaneous image-guided biopsy is not without risk in patients with malignant peripheral nerve sheath tumors (MPNSTs); in particular, there may be concern regarding worsening neurologic function, increasing neuropathic pain, and incorrect or absent diagnosis. METHODS: Following approval by our institutional review board, we reviewed records from 1990 to 2019 at our institution's three main sites ("our institution"). Patients with pathology-proven MPNST were selected. Further inclusion criteria included image-guided percutaneous biopsy performed at our institution, pathology report available for review, and follow-up documentation to determine post-biopsy complications. RESULTS: Three hundred thirty-one patients with MPNST were reviewed. In total, 73 patients undergoing image-guided percutaneous biopsies were included. Twenty-two (30.1%) had biopsy-related complications. This included ten patients with misdiagnosis (13.7%) and six patients with non-diagnostic biopsies (8.2%). Six patients had new or worsened pain that resolved with time and neuropathic pain medication (8.2%), and one patient had subjectively worsened proximal weakness (1.3%) which resolved. CONCLUSION: We found nearly a third of patients undergoing biopsy had a biopsy-related complication. The single largest complication was the inability to obtain an accurate diagnosis (21.9%) with the first biopsy. This may lead to the need for repeat percutaneous or open biopsies, or a non-oncologic initial surgery with implications for disease-free and overall survival. Neurologic complications including exacerbation of pain or a deficit were rare and transient. It remains important that clinicians balance the potential risks and benefits based on individual patient characteristics when determining the necessity of an image-guided percutaneous biopsy.

Quantitative Musculoskeletal Tumor Imaging.

The role of quantitative magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) techniques continues to grow and evolve in the evaluation of musculoskeletal tumors. In this review we discuss the MRI quantitative techniques of volumetric measurement, chemical shift imaging, diffusion-weighted imaging, elastography, spectroscopy, and dynamic contrast enhancement. We also review quantitative PET techniques in the evaluation of musculoskeletal tumors, as well as virtual surgical planning and three-dimensional printing.

Limb Undergrowth in Intraneural Perineuriomas: An Under-Recognized Association.

BACKGROUND: Intraneural (IN) perineuriomas are a rare benign hypertrophic nerve tumor, most frequently occurring in young patients. Patients with IN perineurioma have been anecdotally found to have limb undergrowth; however, this has not been systematically evaluated. METHODS: Archived electronic records from 1990 to 2018 from a single institution were reviewed for pathology or radiology reports documenting a diagnosis of IN perineurioma. This identified 111 patients; 3 patients with IN perineurioma of cranial nerves were excluded. We further reviewed the 108 patients and identified those with a documented limb length discrepancy (LLD) or hand/foot size discrepancy (HFD) and tried to correlate findings with nerve-territory distribution. RESULTS: Twenty-seven (25.0%) patients had either LLD or HFD. Nine patients had only an LLD, 6 patients had only an HFD, and 12 patients had both. Patients with undergrowth were significantly younger at diagnosis than patients without (6.14 vs. 22.9 years, respectively). Although there was a trend toward a greater incidence of LLD in lower extremity IN perineuriomas, this was not statistically significant. Patients with proximal IN perineuriomas had a higher incidence of LLD or HFD than patients with distal IN perineuriomas. The difference between the 2 groups was statistically significant (P < 0.0001). All instances of undergrowth were explained by nerve-territory bone innervation. CONCLUSIONS: Limb undergrowth occurs in the affected nerve territory and is likely under-reported in patients with IN perineuriomas. Within our series, patients with documented LLD and HFD were likely to be significantly younger at diagnosis than patients without undergrowth.

Imaging of the Hand and Wrist.

Imaging plays a key role in the evaluation and treatment planning of hand and wrist injuries in athletes. Depending on the suspected injury, a combination of conventional radiographs, computed tomography, magnetic resonance imaging, magnetic resonance arthrography, and/or ultrasound may be indicated. This article reviews the strengths and limitations of these imaging modalities and how they can be utilized in commonly encountered clinical questions.

Neuromuscular choristoma-associated desmoid-type fibromatosis: Establishing a nerve territory concept.

INTRODUCTION: Desmoid-type fibromatosis (DTF) frequently arises in patients with neuromuscular choristoma (NMC). We hypothesize that NMC-associated DTF occurs in soft tissues innervated by the NMC-affected nerve, and arises from CTNNB1-mutated (myo) fibroblasts within or directly adjacent to the NMC. MATERIALS AND METHODS: A retrospective review of patients treated at our institution was performed for patients with biopsy-confirmed diagnosis of NMC-DTF. Clinical presentation, physical examination, electrodiagnostic findings and radiological features (MR and FDG PET/CT images for each NMC-DTF) and pathologic re-review of available materials were analyzed. A literature review was also performed. RESULTS: Eight patients from our institution met the inclusion criteria. All patients presented with neuropathic symptoms and soft tissue or bone changes in the nerve territory innervated by the NMC. All MR images (N=8 cases) showed the characteristic features of NMC, and also showed direct contact between unifocal (N=5) or multifocal (N=3) DTF(s) and the NMC-affected nerve NMC. FDG PET/CT (N=2 cases) showed diffuse, increased FDG uptake along the entire affected nerve segment, contiguous with the FDG-avid DTF. In all cases, the DTFs arose in the soft tissues of the NMC-affected nerve's territory. No patient developed DTF at any other anatomic site. CONCLUSIONS: These data demonstrate that NMC-DTF arises solely within the NMC-affected nerve territory, and has direct contact with the NMC itself. Based on all these findings and the multifocality of NMC in several cases, we recommend imaging and surveillance of the entire NMC-affected nerve (from spine to distal extremity) to identify clinically-occult DTF in patients with NMC.

Joint Outcomes Following Surgery for Superior Tibiofibular Joint-Associated Peroneal Intraneural Ganglion Cysts.

BACKGROUND: Intraneural ganglion cysts are joint-connected, with the primary pathology residing in the associated joint. For peroneal intraneural ganglion cysts, the surgical strategy can include resection of the synovial surface of the superior tibiofibular joint (STFJ). However, the rate of instability postoperatively is unclear. OBJECTIVE: To evaluate the rate of STFJ instability, following surgery for peroneal intraneural ganglion cysts. The second goal of the study was to assess the relationship between volume of resection of the STFJ and risk of extraneural recurrence. METHODS: We performed a retrospective analysis of a cohort of patients with peroneal intraneural ganglion cysts. We analyzed clinical factors, including recurrence, and assessed the rate of postoperative STFJ instability. We created 3-dimensional models of the STFJ pre- and postoperatively to compare the volume of resection in recurrent cases and nonrecurrent cases using a case-control design. RESULTS: The total cohort consisted of 65 subjects. No patient had evidence of radiological or clinical instability of the STFJ postoperatively. Extraneural radiological recurrence occurred in 6 (9%) patients. No intraneural recurrences were observed. The average volume of resection for patients with recurrence was 1349 mm3 (SD = 1027 mm3) vs 3018 mm3 (SD = 1433 mm3) in controls that did not have a recurrence (P = .018). CONCLUSION: This study supports performing an aggressive STFJ resection to minimize the risk of extraneural recurrence. Superior tibiofibular joint resection is not associated with postoperative joint instability. A smaller volume resection is correlated with recurrence risk.

PIK3CA mutations in lipomatosis of nerve with or without nerve territory overgrowth.

Lipomatosis of nerve is a rare malformation characterized by a fibrolipomatous proliferation within peripheral nerve. Lipomatosis of nerve most frequently involves the median nerve, and manifests clinically as a compressive neuropathy. However, 30-60% of cases are associated with tissue overgrowth within the affected nerve's territory (e.g., macrodactyly for lipomatosis of nerve in the distal median nerve). Somatic activating PIK3CA mutations have been identified in peripheral nerve from patients with lipomatosis of nerve with type I macrodactyly, which is now classified as a PIK3CA-related overgrowth spectrum disorder. However, the PIK3CA mutation status of histologically confirmed lipomatosis of nerve, including cases involving proximal nerves, and cases without territory overgrowth, has not been determined. Fourteen histologically confirmed cases of lipomatosis of nerve involving the median (N = 6), brachial plexus (N = 1), ulnar (N = 3), plantar (N = 2), sciatic and superficial peroneal nerves (N = 1 each) were included. Ten cases had nerve territory overgrowth, ranging from macrodactyly to hemihypertrophy; and four cases had no territory overgrowth. Exome sequencing revealed "hotspot" activating PIK3CA missense mutations in 6/7 cases. Droplet digital polymerase chain reaction for the five most common PIK3CA mutations (p.H1047R, p.H1047L, p.E545K, p.E542K, and p.C420R) confirmed the exome results and identified an additional six cases with mutations (12/14 total). PIK3CA mutations were found in 8/10 cases with territory overgrowth (N = 7 p.H1047R and N = 1 p.E545K), including two proximal nerve cases with extremity overgrowth, and 4/4 cases without territory overgrowth (p.H1047R and p.H1047L, N = 2 each). The variant allele frequency of PIK3CA mutations (6-32%) did not correlate with the overgrowth phenotype. Three intraneural lipomas had no detected PIK3CA mutations. As PIK3CA mutations are frequent events in lipomatosis of nerve, irrespective of anatomic site or territory overgrowth, we propose that all phenotypic variants of this entity be classified within the PIK3CA-related overgrowth spectrum and termed "PIK3CA-related lipomatosis of nerve".

Nomenclature of Subchondral Nonneoplastic Bone Lesions.

OBJECTIVE. The purpose of this article is to summarize the nomenclature of nonneoplastic conditions affecting subchondral bone through a review of the medical literature and expert opinion of the Society of Skeletal Radiology Subchondral Bone Nomenclature Committee. CONCLUSION. This consensus statement summarizes current understanding of the pathophysiologic characteristics and imaging findings of subchondral nonneoplastic bone lesions and proposes nomenclature to improve effective communication across clinical specialties and help avoid diagnostic errors that could affect patient care.

Clinical and Magnetic Resonance Imaging Longitudinal Follow-up of Neuromuscular Choristomas.

INTRODUCTION: The natural history of growth and radiologic progression of neuromuscular choristomas (NMCs) remain unknown. The purpose of this study was to describe the radiologic growth pattern of NMCs and to determine how the pattern of growth relates to clinical progression. METHODS: A retrospective review was performed for patients with a confirmed diagnosis of NMC and at least 2 years of radiologic (magnetic resonance imaging [MRI]) follow-up. Medical records, including physical examinations and radiologic studies, were reviewed in detail. The NMC length and transverse dimensions were compared between serial MRI examinations. RESULTS: Eleven patients with a mean radiologic follow-up time of 5.6 years (range 2-19 years) were identified. Motor deficits occurred in 10 patients (90%), sensory deficits in 5 patients (45%), and neuropathic pain in 4 (36%) patients. Eight patients (73%) presented with manifestations of limb undergrowth, 2 (18%) with congenital hip dysplasia, and 1 with a cavus foot deformity. Progression of motor and sensory deficits was observed in 5 (45%) and 1 (9%) patients, respectively. The maximal length and height of the NMC was significantly (P < 0.05) longer (initial 218 ± 118 mm vs. follow-up 270 ± 135 mm) and larger (20 ± 10 mm vs. 24 ± 14 mm) on the follow-up scan. MRI demonstrated abnormalities that were in continuity along the longitudinal extent of the NMC. CONCLUSIONS: According to this small but relatively long-term follow-up cohort, the growth pattern of this lesion is slow but progressive. We found a longitudinal continuity pattern of growth in all MRI scans, often spanning a great distance.

Multimodal Imaging Aids in the Diagnosis of Perineural Spread of Prostate Cancer.

BACKGROUND: The perineural spread of prostate cancer into pelvic peripheral nerves is a rare, but increasingly recognized, entity. This form of metastasis invades the lumbosacral plexus via the splanchnic nerves innervating the prostate. The prevalence of perineural spread is likely underappreciated, and further imaging-based studies are needed to elucidate its true frequency. METHODS: A retrospective review was performed using an institutional radiology database. Medical reports from patients with prostate cancer who had undergone positron emission tomography (PET) imaging were queried for terms suggestive of perineural spread. PET and magnetic resonance imaging (MRI) from the identified patients were blindly reviewed for peripheral nerve involvement by 2 nuclear medicine and 2 musculoskeletal radiologists. RESULTS: A total of 22 patients were identified. After review by the radiologists, 16 patients had positive findings of perineural spread found on PET and 15 had abnormalities found on MRI involving lumbosacral plexus neural elements. All patients with biopsy-proven neoplastic perineural spread (including 1 patient with malignant peripheral nerve sheath tumor) had positive findings on both PET and MRI. All patients with biopsy-proven inflammatory lesions had negative PET and variable MRI findings. CONCLUSIONS: The perineural spread of prostate cancer might be more common than previously thought. The use of multimodal imaging for patients suspected of having perineural spread should be a part of the treatment algorithm. Targeted fascicular biopsy might be indicated for patients with progressive neurological deficit and an unclear diagnosis.

Clinical and Radiological Follow-up of Intraneural Perineuriomas.

BACKGROUND: Management of intraneural perineuriomas remains controversial, largely due to the lack of knowledge regarding the natural history of these lesions. OBJECTIVE: To describe the typical radiological growth pattern of intraneural perineuriomas and to determine how the pattern of growth relates to clinical progression. METHODS: We performed a retrospective review of the magnetic resonance imaging (MRI) studies and serial clinical examinations of a cohort of patients with biopsy-proven intraneural perineuriomas who had 2 MRI studies at least 2 yr apart. The outcome of interest was radiological growth in length or width of the intraneural perineurioma. Radiological growth was tested for association with clinical progression. RESULTS: Twenty patients were included in the study. By width, the lesions were on average larger on repeat imaging (P = .009). By absolute length, the lesions were on average longer on repeat imaging (P = .02). By lesion:landmark ratio, there was no difference in length of the lesions between sequential images (P = .09), with 10 (50%) lesions being shorter and 7 (35%) showing no change. No lesions grew to involve a new nerve or division of a nerve on sequential imaging. None of the variables tested were associated with clinical progression. CONCLUSION: We found that intraneural perineuriomas only rarely grow in length, do not grow to involve new nerves or nerve divisions, and growth does not correlate with clinical progression. These findings have significant ramifications for management of these tumors.

Soft Tissue Sarcoma Stiffness and Perfusion Evaluation by MRE and DCE-MRI for Radiation Therapy Response Assessment: A Technical Feasibility Study.

Soft tissue sarcomas are a rare and heterogeneous group of malignancies that present significant diagnostic and therapeutic challenges. Patient stratification based on tumor aggressiveness and early therapeutic response based on quantitative imaging may improve prediction of treatment response and the evaluation of new treatment strategies in clinical trials. The purpose of this pilot study was to determine the technical feasibility of magnetic resonance elastography (MRE) and dynamic contrast-enhanced (DCE) MRI for the evaluation of sarcoma stiffness and perfusion in 9 patients with histologically confirmed sarcoma. Additionally, we assessed the feasibility of utilizing MRE and DCE-MRI for the early evaluation of response to radiation therapy in 4 patients to determine the utility of further evaluation in a larger cohort study. Tumor size, stiffness, and perfusion parameters all decreased from baseline at the time of the pre-surgery or follow-up MRI, and results were compared to pathology or conventional imaging. MRE and DCE-MRI may be useful for the quantitative evaluation of tumor stiffness and perfusion, and therapy response assessment in soft tissue sarcomas.

Recurrent desmoid-type fibromatosis associated with underlying neuromuscular choristoma.

OBJECTIVE: Desmoid-type fibromatosis (DTF) presents a therapeutic dilemma. While lacking metastatic potential, it is a locally aggressive tumor with a strong propensity for occurrence near nerve(s) and recurrence following resection. In this study, the authors introduce the association of an occult neuromuscular choristoma (NMC) identified in patients with DTF. METHODS: After experiencing a case of DTF found to have an occult NMC, the authors performed a retrospective database review of all other cases of biopsy-proven DTF involving the extremities or limb girdles in patients with available MRI data. Two musculoskeletal radiologists with expertise in peripheral nerve imaging reviewed the MRI studies of the eligible cases for evidence of previously unrecognized NMC. RESULTS: The initial case of a patient with an occult sciatic NMC is described. The database review yielded 40 patients with DTF-18 (45%) in the upper limb and 22 (55%) in the lower limb. Two cases (5%) had MRI findings of NMC associated with the DTF, one in the proximal sciatic nerve and the other in the proximal tibial and sural nerves. CONCLUSIONS: The coexistence of NMC may be under-recognized in a subset of patients with extremity DTF. This finding poses implications for DTF treatment and the likelihood of recurrence after resection or biopsy. Further study may reveal crucial links between the pathogenesis of NMC and DTF and offer novel therapeutic strategies.