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Ultrasonography of peripheral nerve tumours: a case series

Simon Podnar
Simon Podnar
   | 20 ene 2023
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Article Category: Research Article
Publicado en línea: 20 ene 2023
Páginas: 35 - 41
Recibido: 05 ago 2022
Aceptado: 08 dic 2022
DOI: https://doi.org/10.2478/raon-2023-0005
© 2023 Simon Podnar, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure

(A) Transverse ultrasonographic (US) view of the median (M) and ulnar (U) nerve in the axillary region showing numerous globular hypoechoic peripheral nerve tumours (PNTs) causing largely increased nerve cross sectional areas (CSAs, 148 mm2 and 101 mm2, respectively). (B) Longitudinal view of a single partially encapsulated, slightly lobulated and rather homogenous oval PNT (length 24 mm, thickness 9 mm) with central, but poorly defined nerve-tumour transition.5 Most probably these numerous PNTs are neurofibromas, although diagnosis in this 52-year-old woman presenting with peripheral neuropathy, primary lymphedema, and history of mitral and aortic valve surgery (patient #13, Tables 2–3), is not known yet.
(A) Transverse ultrasonographic (US) view of the median (M) and ulnar (U) nerve in the axillary region showing numerous globular hypoechoic peripheral nerve tumours (PNTs) causing largely increased nerve cross sectional areas (CSAs, 148 mm2 and 101 mm2, respectively). (B) Longitudinal view of a single partially encapsulated, slightly lobulated and rather homogenous oval PNT (length 24 mm, thickness 9 mm) with central, but poorly defined nerve-tumour transition.5 Most probably these numerous PNTs are neurofibromas, although diagnosis in this 52-year-old woman presenting with peripheral neuropathy, primary lymphedema, and history of mitral and aortic valve surgery (patient #13, Tables 2–3), is not known yet.

Figure

Comparison of transverse image of the sciatic peripheral nerve tumour (PNT) on (A) magnetic resonance (MR) T1 (arrow) and (B) ultrasonography (US). (C) Longitudinal US view of PNT in the middle thigh (A – small picture on the left), affecting the tibial portion of sciatic nerve. In this 22-year-old girl MR revealed at the exit of sciatic nerve from the pelvis another PNT affecting its fibular portion, and causing right foot drop of 14 years duration (patient #10, Tables 2–3). Based on clinical and imaging features in this patient diagnosis of probable perineurioma was made.
Comparison of transverse image of the sciatic peripheral nerve tumour (PNT) on (A) magnetic resonance (MR) T1 (arrow) and (B) ultrasonography (US). (C) Longitudinal US view of PNT in the middle thigh (A – small picture on the left), affecting the tibial portion of sciatic nerve. In this 22-year-old girl MR revealed at the exit of sciatic nerve from the pelvis another PNT affecting its fibular portion, and causing right foot drop of 14 years duration (patient #10, Tables 2–3). Based on clinical and imaging features in this patient diagnosis of probable perineurioma was made.

Figure

(A) Transverse and (B) longitudinal ultrasonographic (US) view of a large peripheral nerve tumour (PNT) on the left ulnar nerve just above the elbow. Three years before this 47-year-old man noted a palpable mass that in the last 6 months on touching started to elicit electrisation spreading into the last two fingers (patient #8, Tables 2–3). Well encapsulated, slightly lobulated, predominantly cystic and highly heterogenous hypoechoic oval lesion with central and poorly defined nerve-tumour transition can be seen. Histological examination confirmed a diagnosis of schwannoma.
(A) Transverse and (B) longitudinal ultrasonographic (US) view of a large peripheral nerve tumour (PNT) on the left ulnar nerve just above the elbow. Three years before this 47-year-old man noted a palpable mass that in the last 6 months on touching started to elicit electrisation spreading into the last two fingers (patient #8, Tables 2–3). Well encapsulated, slightly lobulated, predominantly cystic and highly heterogenous hypoechoic oval lesion with central and poorly defined nerve-tumour transition can be seen. Histological examination confirmed a diagnosis of schwannoma.

Figure

(A) Hands of a 26-year-old woman with 4-year history of muscle atrophy, weakness and numbness in the distal ulnar nerve territory (patient #5, Tables 2–3). Note intrinsic right palm muscle atrophy and clawing of the last two fingers. (B) On transverse ultrasonographic (US) view ulnar nerve cross sectional area (CSA) increased from 7 mm2 both proximally and distally to 20 mm2 in the middle of the lesion. (C) On longitudinal view a partially encapsulated, lobulated, fusiform hypoechoic right ulnar peripheral nerve tumour (PNT) of the forearm can be seen. Based on clinical and US features, we made a diagnosis of probable perineurioma.
(A) Hands of a 26-year-old woman with 4-year history of muscle atrophy, weakness and numbness in the distal ulnar nerve territory (patient #5, Tables 2–3). Note intrinsic right palm muscle atrophy and clawing of the last two fingers. (B) On transverse ultrasonographic (US) view ulnar nerve cross sectional area (CSA) increased from 7 mm2 both proximally and distally to 20 mm2 in the middle of the lesion. (C) On longitudinal view a partially encapsulated, lobulated, fusiform hypoechoic right ulnar peripheral nerve tumour (PNT) of the forearm can be seen. Based on clinical and US features, we made a diagnosis of probable perineurioma.

Morphological features useful for differentiation between neurofibromas and schwannomas5

Peripheral nerve tumor (PNT) feature Comment
Maximum to minimum diameter Ratio > 3 → neurofibroma
Shape: round, oval, fusiform Fusiform → neurofibroma
Contour: smooth, lobulated Lobulated → neurofibroma
Encapsulation: absent, partial, complete Complete → schwannoma
Echogenicity: hypo-, iso-, hyper- Hypoechoic → PNT
Echo texture: homogenous, heterogenous Heterogenous → schwannoma
Cystic changes: absent, focal, partial, Cystic changes →
large schwannoma
Calcifications: absent, present Present → schwannoma
Target sign: absent, present
Nerve entrance: not identified, identified
Nerve-tumor position: central, eccentric Central → neurofibroma
Nerve-tumor transition: clear, poorly defined, infiltrative Infiltrative → neurofibroma
Vascularity: increased, normal, decreased Hypovascular → neurofibroma

Morphological features of peripheral nerve tumors (PNTs) found on ultrasonographic (US) examination5 of individual patients

# Ratio Shape Contour Encapsulation Echo texture Nerve position Nerve transition Number Tumor diagnosis
1 5 Fusiform Lobulated Partial Heterogeneous Central Infiltrative Single Neurofibroma
2 ? Lobulated Partial Heterogeneous ? ? Several Schwannoma*
3 6 Fusiform Smooth Whole Heterogeneous Central Poorly defined Single Schwannoma
4 6 Fusiform Fusiform None Heterogeneous Central Infiltrative Several Neurofibroma
5 8 Fusiform Lobulated Partial Heterogeneous Central Infiltrative Single Perineurioma
6 > 10 Fusiform Lobulated Partial Heterogeneous ? ? Single Perineurioma
7 6 Fusiform Smooth None Homogenous Central Infiltrative Single Perineurioma
8 3 Oval Smooth Whole Heterogeneous Central Poorly defined Single Schwannoma*
9 > 10 Fusiform Lobulated Partial Heterogeneous Eccentric Infiltrative Single Neurofibroma
10 5 Fusiform Smooth Whole Heterogeneous Central Infiltrative Several Perineurioma
11 1,5 Oval Smooth Whole Homogenous Eccentric ? Single Schwannoma*
12 2,5 Oval Smooth Whole Heterogeneous Central Poorly defined Single Schwannoma*
13 2,5 Oval Smooth Whole Heterogeneous Central Poorly defined Several Neurofibroma
14 4 Fusiform Lobulated Partial Heterogeneous Central Infiltrative Several Neurofibroma*
15 1,7 Oval Smooth Whole Heterogeneous Eccentric Poorly defined Single Schwannoma

Demographic, anatomical, clinical, electrodiagnostic (EDx) and ultrasonographic (US) features of patients with peripheral nerve tumors (PNTs)

# Gender Age Side Nerve Location Symptoms & Signs CMAP amp. (mV) SNAP amp. (μ V) Tumor CSA (mm2) Tumor diagnosis Other
1 Male 69 R Ulnar Elbow AWS 43 Neurofibroma
2 Male 24 L #Radial Upper arm W 0.2 4 24 Schwannoma* NF2
3 Male 66 R Median Forearm Æ 6.9 5 49 Schwannoma
4 Male 16 L #Median Upper arm WS 61 Neurofibroma NF1
5 Female 26 R Ulnar Forearm AWS 0.2 0 30 Perineurioma
6 Female 18 L Sciatic Thigh AWS 0.4 0 109 Perineurioma
7 Female 18 R Fibular Knee AWS 0 0 47 Perineurioma
8 Male 47 L Ulnar Elbow M 7.6 3 348 Schwannoma*
9 Female 58 R Median Forearm P 7.6 16 45 Neurofibroma
10 Female 22 R Sciatic Thigh AWS 0 0 97 Perineurioma
11 Female 34 R Tibial Ankle PAWS 10.6 7 1250 Schwannoma*
12 Male 63 L Ulnar Elbow L 8.2 5 368 Schwannoma*
13 Female 52 R #Ulnar Forearm 6.2 12 212 Neurofibroma NF?
14 Male 24 R #Median Upper arm P 6.3 33 26 Neurofibroma* NF1
15 Female 33 L Tibial Ankle L 92 Schwannoma
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Medicina, Medicina Clínica, Medicina Interna, Hematología, oncología, Radiología
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