Neuromuscular choristoma
Updates to Article Attributes
Benign Triton tumours or neuromuscular choristomas (NMC) are benign expansile peripheral nerve sheath tumours featuring a tight interconnection of sceletalskeletal muscle and nerve fibres within the endoneurial sheath. It seems to have ana precursor role in desmoid-type fibromatosis.
Terminology
Other acceptable terminologyterminologies for the entity include neuromuscular or ectomesenchymal harmatoma or nerve rhabomyomarhabdomyoma 1.
Epidemiology
Benign Triton tumours are extremlyextremely rare and are usually seen in childhood or adolescence. There is no gender predelictionpredilection 1.
Associations
Neuromuscular choristoma is associated wit desmoid-type fibromatosis 1-3.
Clinical presentation
Typical clinical features include signs of neuropathy or plexopathy with muscular atrophy as well as progressive pain 1,2.
Pathology
Benign Triton tumours are peripheral nerve tumours where skeletal muscle fibres are positioned within a nerve and its fibres 1-3.
Aetiology
Hypotheses about the aetiology of benign Triton tumour include the following 1,3:
- harmatous overgrowth of muscle spindles
- intraneural entrapment of skeletal muscle during embryogenesis
- myogenic metaplasia of nerve sheath components
- intraneural rhabdomyoma
Location
Neuromuscular choristomas have been reported in large nerves or within the plexus as the sciatic nerve and the brachial plexus. They have been also described in cranial nerves or intraorbitallyintraorbital 1-5.
Macroscopic appearance
Macroscopically benign Triton tumours show a multifascicularmulti fascicular fusiform nerve enlargement with some nerve fascicles showeingshowing a red muscle-like appearance. Nerve stimulation causes contraction of the whole nerve in addition to the innervated muscle 1.
Microscopic appearance
Microscopically benign Triton tumours are characterised by disorganized fascicles of skeletal muscle intertwined with nerve fascicles or neural elements 1-4.
Immunophenotype
Immunohistochemistry stains are positive for desmin and muscle specific-specific actin as well as S100, and possibly epithelial membrane antigen (EMA) and possiblyor β-catenin 1-3.
Genetics
Most cases of neuromuscular choristomas show a CTNNB1 mutation 1,2.
Radiographic features
MRI
Typical magnetic resonmanceresonance imaging features include fusiform enlargement of the nerve with characteriticscharacteristics resembling skeletal musculature, as long as there is no associated desmoid tumour 1-4.
Signal characteristics
·
-
T1: isointense or slightly hypointense to muscle
· -
T2: isointense or slightly hypointense to muscle
· - T1 C+ (Gd): mild heterogeneous contrast enhancement
Radiology report
The radiological report should include a description of the following:
- form, location and size
- tumour margins and transition zone
- affected nerve/plexus and relations to
asjacentadjacent neurovascular structures - interfascicular fat
- associated desmoid tumour if present
- relations to bones
Treatment and prognosis
Neuromuscular choristoma is benign and therefore does not require an overly aggressive approach. Since a trauma or surgery related stimulation of desmoid-type fibromatosis has been considered and the latter requires an aggressive management a do not touch approach has been advocated in patients in whom the diagnosis is clinicallyyclinically and radiologically clear 1,4.
History and etymology
Neuromuscular choristoma werewas first described by E. Orlandi in 1895 3,4.
Differential diagnosis
Tumours or conditions which can mimic the presentation and/or appearance of a benign Triton tumour include 1:
fibrolipomatous
- lipofibromatous harmatoma: interfascicular fat
-
neurofibroma: contrast enhancement
schwannomma - schwannoma: contrast enhancement
- rhabdomyoma
- embryonal rhabdomyosarcoma
-<p><strong>Benign Triton tumours </strong>or<strong> neuromuscular choristomas (NMC) </strong>are benign expansile peripheral nerve sheath tumours featuring a tight interconnection of sceletal muscle and nerve fibres within the endoneurial sheath. It seems to have an precursor role in desmoid-type fibromatosis.</p><h4>Terminology</h4><p>Other acceptable terminology for the entity include <strong>neuromuscular</strong> or <strong>ectomesenchymal harmatoma</strong> or <strong>nerve rhabomyoma</strong> <sup>1</sup>.</p><h4>Epidemiology</h4><p>Benign Triton tumours are extremly rare and are usually seen in childhood or adolescence. There is no gender predeliction <sup>1</sup>.</p><h5>Associations</h5><p>Neuromuscular choristoma is associated wit desmoid-type fibromatosis <sup>1-3</sup>.</p><h4>Clinical presentation</h4><p>Typical clinical features include signs of neuropathy or plexopathy with muscular atrophy as well as progressive pain <sup>1,2</sup>.</p><h4>Pathology</h4><p>Benign Triton tumours are peripheral nerve tumours where skeletal muscle fibres are positioned within a nerve and its fibres <sup>1-3</sup>.</p><h5>Aetiology</h5><p>Hypotheses about the aetiology of benign Triton tumour include the following <sup>1,3</sup>:</p><p>harmatous overgrowth of muscle spindles</p><p>intraneural entrapment of skeletal muscle during embryogenesis</p><p>myogenic metaplasia of nerve sheath components</p><p>intraneural rhabdomyoma</p><h5>Location</h5><p>Neuromuscular choristomas have been reported in large nerves or within the plexus as the sciatic nerve and the brachial plexus. They have been also described in cranial nerves or intraorbitally <sup>1-5</sup>.</p><h5>Macroscopic appearance</h5><p>Macroscopically benign Triton tumours show a multifascicular fusiform nerve enlargement with some nerve fascicles showeing a red muscle-like appearance. Nerve stimulation causes contraction of the whole nerve in addition to the innervated muscle <sup>1</sup>.</p><h5>Microscopic appearance</h5><p>Microscopically benign Triton tumours are characterised by disorganized fascicles of skeletal muscle intertwined with nerve fascicles or neural elements <sup>1-4</sup>.</p><h5>Immunophenotype</h5><p>Immunohistochemistry stains are positive for desmin and muscle specific actin as well as S100, epithelial membrane antigen (EMA) and possibly β-catenin <sup>1-3</sup>.</p><h5>Genetics</h5><p>Most cases of neuromuscular choristomas show a <em>CTNNB1</em> mutation <sup>1,2</sup>.</p><h4>Radiographic features</h4><h5>MRI</h5><p>Typical magnetic resonmance imaging features include fusiform enlargement of the nerve with characteritics resembling skeletal musculature, as long as there is no associated desmoid tumour <sup>1-4</sup>.</p><h6>Signal characteristics</h6><p><!--[if !supportLists]-->· <!--[endif]--><strong>T1:</strong> isointense or slightly hypointense to muscle</p><p><!--[if !supportLists]-->· <!--[endif]--><strong>T2: </strong>isointense or slightly hypointense to muscle</p><p><!--[if !supportLists]-->· <!--[endif]--><strong>T1 C+ (Gd): </strong>mild heterogeneous contrast enhancement</p><h4>Radiology report</h4><p>The radiological report should include a description of the following:</p><p>form, location and size</p><p>tumour margins and transition zone</p><p>affected nerve/plexus and relations to asjacent neurovascular structures</p><p>interfascicular fat</p><p>associated desmoid tumour if present</p><p>relations to bones</p><h4>Treatment and prognosis</h4><p>Neuromuscular choristoma is benign and therefore does not require an overly aggressive approach. Since a trauma or surgery related stimulation of desmoid-type fibromatosis has been considered and the latter requires an aggressive management a do not touch approach has been advocated in patients in whom the diagnosis is clinicallyy and radiologically clear <sup>1,4</sup>.</p><h4>History and etymology</h4><p>Neuromuscular choristoma were first described by E. Orlandi in 1895 <sup>3,4</sup>.</p><h4>Differential diagnosis</h4><p>Tumours or conditions which can mimic the presentation and/or appearance of a benign Triton tumour include <sup>1</sup>:</p><p>fibrolipomatous harmatoma: interfascicular fat</p><p>neurofibroma: contrast enhancement</p><p>schwannomma: contrast enhancement</p>- +<p><strong>Benign Triton tumours </strong>or<strong> neuromuscular choristomas (NMC) </strong>are benign expansile <a href="/articles/peripheral-nerve-sheath-tumours">peripheral nerve sheath tumours</a> featuring a tight interconnection of skeletal muscle and nerve fibres within the endoneurial sheath. It seems to have a precursor role in <a href="/articles/aggressive-fibromatosis">desmoid-type fibromatosis</a>.</p><h4>Terminology</h4><p>Other acceptable terminologies for the entity include <strong>neuromuscular</strong> or <strong>ectomesenchymal harmatoma</strong> or <strong>nerve rhabdomyoma</strong> <sup>1</sup>.</p><h4>Epidemiology</h4><p>Benign Triton tumours are extremely rare and are usually seen in childhood or adolescence. There is no gender predilection <sup>1</sup>.</p><h5>Associations</h5><p>Neuromuscular choristoma is associated wit <a href="/articles/aggressive-fibromatosis">desmoid-type fibromatosis</a> <sup>1-3</sup>.</p><h4>Clinical presentation</h4><p>Typical clinical features include signs of neuropathy or plexopathy with muscular atrophy as well as progressive pain <sup>1,2</sup>.</p><h4>Pathology</h4><p>Benign Triton tumours are peripheral nerve tumours where skeletal muscle fibres are positioned within a nerve and its fibres <sup>1-3</sup>.</p><h5>Aetiology</h5><p>Hypotheses about the aetiology of benign Triton tumour include the following <sup>1,3</sup>:</p><ul>
- +<li>harmatous overgrowth of muscle spindles</li>
- +<li>intraneural entrapment of skeletal muscle during embryogenesis</li>
- +<li>myogenic metaplasia of nerve sheath components</li>
- +<li>intraneural rhabdomyoma</li>
- +</ul><h5>Location</h5><p>Neuromuscular choristomas have been reported in large nerves or within the plexus as the sciatic nerve and the brachial plexus. They have been also described in cranial nerves or intraorbital <sup>1-5</sup>.</p><h5>Macroscopic appearance</h5><p>Macroscopically benign Triton tumours show a multi fascicular fusiform nerve enlargement with some nerve fascicles showing a red muscle-like appearance. Nerve stimulation causes contraction of the whole nerve in addition to the innervated muscle <sup>1</sup>.</p><h5>Microscopic appearance</h5><p>Microscopically benign Triton tumours are characterised by disorganized fascicles of skeletal muscle intertwined with nerve fascicles or neural elements <sup>1-4</sup>.</p><h5>Immunophenotype</h5><p>Immunohistochemistry stains are positive for desmin and muscle-specific actin as well as S100, and possibly epithelial membrane antigen (EMA) or β-catenin <sup>1-3</sup>.</p><h5>Genetics</h5><p>Most cases of neuromuscular choristomas show a <em>CTNNB1</em> mutation <sup>1,2</sup>.</p><h4>Radiographic features</h4><h5>MRI</h5><p>Typical magnetic resonance imaging features include fusiform enlargement of the nerve with characteristics resembling skeletal musculature, as long as there is no associated <a href="/articles/desmoid-tumour">desmoid tumour</a> <sup>1-4</sup>.</p><h6>Signal characteristics</h6><ul>
- +<li>
- +<strong>T1:</strong> isointense or slightly hypointense to muscle</li>
- +<li>
- +<strong>T2: </strong>isointense or slightly hypointense to muscle</li>
- +<li>
- +<strong>T1 C+ (Gd): </strong>mild heterogeneous contrast enhancement</li>
- +</ul><h4>Radiology report</h4><p>The radiological report should include a description of the following:</p><ul>
- +<li>form, location and size</li>
- +<li>tumour margins and transition zone</li>
- +<li>affected nerve/plexus and relations to adjacent neurovascular structures</li>
- +<li>interfascicular fat</li>
- +<li>associated desmoid tumour if present</li>
- +<li>relations to bones</li>
- +</ul><h4>Treatment and prognosis</h4><p>Neuromuscular choristoma is benign and therefore does not require an overly aggressive approach. Since a trauma or surgery related stimulation of desmoid-type fibromatosis has been considered and the latter requires an aggressive management a do not touch approach has been advocated in patients in whom the diagnosis is clinically and radiologically clear <sup>1,4</sup>.</p><h4>History and etymology</h4><p>Neuromuscular choristoma was first described by E. Orlandi in 1895 <sup>3,4</sup>.</p><h4>Differential diagnosis</h4><p>Tumours or conditions which can mimic the presentation and/or appearance of a benign Triton tumour include <sup>1</sup>:</p><ul>
- +<li>
- +<a href="/articles/fibrolipomatous-hamartoma-of-the-nerve">lipofibromatous harmatoma</a>: interfascicular fat</li>
- +<li>
- +<a href="/articles/neurofibroma">neurofibroma</a>: contrast enhancement</li>
- +<li>
- +<a href="/articles/schwannoma">schwannoma</a>: contrast enhancement</li>
- +<li><a href="/articles/rhabdomyoma">rhabdomyoma</a></li>
- +<li><a href="/articles/embryonal-rhabdomyosarcoma">embryonal rhabdomyosarcoma</a></li>
- +</ul>
References changed:
- 1. Perry A. Neuromuscular choristoma. In: WHO Classification of Tumours Editorial Board. Soft tissue and bone tumours. Lyon (France): International Agency for Research on Cancer; 2020. (WHO classification of tumours series, 5th ed.; vol. 3). <a href="https://publications.iarc.fr/Book-And-Report-Series/Who-Classification-Of-Tumours/Soft-Tissue-And-Bone-Tumours-2020">https://publications.iarc.fr</a>
- 2. Stone J, Prasad N, Laumonerie P et al. Recurrent Desmoid-Type Fibromatosis Associated with Underlying Neuromuscular Choristoma. J Neurosurg. 2019;131(1):175-83. <a href="https://doi.org/10.3171/2018.3.jns152935">doi:10.3171/2018.3.jns152935</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/30168738">Pubmed</a>
- 3. Hébert-Blouin M, Scheithauer B, Amrami K, Durham S, Spinner R. Fibromatosis: A Potential Sequela of Neuromuscular Choristoma. JNS. 2012;116(2):399-408. <a href="https://doi.org/10.3171/2011.6.jns102171">doi:10.3171/2011.6.jns102171</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/21819193">Pubmed</a>
- 4. Lam S, Grandhi R, Wong R, Hamilton R, Greene S. Neuromuscular Hamartoma of the Sciatic Nerve: Case Report and Review of the Literature. Surg Neurol Int. 2013;4(1):8. <a href="https://doi.org/10.4103/2152-7806.106266">doi:10.4103/2152-7806.106266</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/23493803">Pubmed</a>
- 5. Castro D, Raghuram K, Phillips C. Benign Triton Tumor of the Trigeminal Nerve. AJNR Am J Neuroradiol. 2005;26(4):967-9. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7977105">PMC7977105</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/15814954">Pubmed</a>
Systems changed:
- Musculoskeletal
- Oncology