【One case per day】MRI diagnosis of intramedullary schwannoma was 1 case

Schwannoma originates from myelin Schwann cells, is the most common tumor in the spinal canal, accounting for 30% of spinal canal tumors, because the spinal cord does not contain myelin or Schwann cells, so the schwannoma that occurs in the medullary only accounts for 0.
3% ~ 1.
5%
of the neuraxial schwannoma.
Intraspinal schwannoma is rare and easy to misdiagnose before surgery, and this article analyzes the MRI imaging data of a case of intramedullary nerve sheath tumor confirmed by surgical pathology to improve the MRI diagnosis and differential diagnosis of
the disease.

1 Information and methods

1.
1 Clinical data

Male, 42 years old, chest and back pain with a feeling of stepping on cotton when walking with both lower limbs for more than
1 month.
The patient is generally in good condition and has no obvious positive signs
on examination.

1.
2 Inspection method

MRI examination using Philips Medical system Intera 1.
5T MR, TSE sequence: sagittal T1WI, TR=480 ms, TE=11 ms; Sagittal T2WI, TR=2729 ms, TE=120 ms; Augmentation using TSE sequences, sagittal and axial T1WI, TR=400 ms, TE=13 ms, contrast agent Gd-DTPA (10 mL).

2 Results

2.
1 MRI findings

T2WI sagittal position showed that the spinal cord of the T3~T5 vertebral body segment was swollen and showed edema-like high signal intensity, and a slightly high-signal nodule shadow of about 5 mm×6 mm×5 mm in size was visible on the right side of the dorsal side of the spinal cord at the level of the T4~T5 intervertebral disc, which protruded from the contour of the spinal cord and was clearly demarcated from the edema spinal cord (Fig.
1); T1WI sagittal position: the spinal cord of edema in the T3~T5 vertebral segment is not clearly demarcated from the shadow of the above small nodule, and the signal intensity is slightly lower (Figure 2); MR enhanced scanning T1WI sagittal position and transverse axis position showed that the small nodule shadow on the dorsal right side of the spinal cord (7 o'clock orientation) at the level of T4~T5 intervertebral disc was obviously uniformly strengthened, with clear boundaries, and the adjacent spinal edema area was not strengthened (Fig.
3, 4), and the diagnosis of intraspinal hemangioblastoma before MRI was possible
.

Fig.
1 The spinal cord swelling of the T3~T5 vertebral body segment shows edema-like high signal intensity, and a slightly high-signal small nodule shadow can be seen on the right side of the dorsal side of the spinal cord at the level of T4~T5 intervertebral disc, which protrudes locally outside the spinal cord contour, and the boundary with the edema spinal cord is still clear

Fig.
2 The demarcation between the spinal cord and the small nodule shadow of edema in the T1WIT3~T5 vertebral segment is not clear, and the signal intensity is slightly lower

Fig.
3, 4 MR enhanced scan T1WI sagittal position and transverse axis position showed that the small nodule shadow on the right side of the dorsal side of the spinal cord (7 o'clock orientation) at the level of T4~T5 intervertebral disc was obviously uniformly strengthened, the boundary was clear, and the adjacent spinal cord edema area was not strengthened

2.
2 Surgery and pathological results

During surgical resection, the lesion observed is located on the right side of the spinal cord, and the size of the lesion is about 5 mm× 6 mm×5 mm
.
Pathological diagnosis of spinal schwannoma, HE staining, tumor cells arranged in bundles under 10× light microscopy, dense phases, interstitial mucinous changes in some areas, and stellar reticular cells; Tumor cells are spindle-shaped, less cytoplasmic, lightly stained, the nucleus is slender, the chromatin is slightly darker, the peripheral blood vessels are dilated, the tube wall is thickened, and a few foamy cells are seen (Figure 6).

Postoperative re-MRI enhanced sagittal location showed that the tumor in the spinal cord in the surgical area disappeared and the spinal cord edema was reduced (Fig.
5).

Fig.
5 Postoperative MRI enhanced scanning sagittal position indicates that the tumor in the spinal cord in the surgical area has disappeared and the spinal cord edema has been reduced

Fig.
6 Pathological diagnosis is intraspinal schwannoma, tumor cells are arranged in bundles under light microscopy, dense phases, interstitial mucus-like changes in some areas, and cells are star-reticulated; The tumor cells are spindle-shaped, less cytoplasmic, lightly stained, the nucleus is slender, and the chromatin is slightly darker; Peripheral blood vessels dilate, tube walls thicken, and few foamy cells (HE×10)

3 Discussion

3.
1 Source of occurrence

Since Penfild et al.
first reported in 1931, Bernal-Garcia et al.
reviewed foreign literature to report 71 cases of intramedullary schwannoma, and searched CNKI database for domestic literature reports from 1986 to 2010 for 42 cases
.
There is no accepted explanation
for the source of intramedullary schwannomas.
According to clinical, surgical and pathological speculations, there are mainly the following causes: Schwann cells originating from the posterior roots of spinal nerves; Derived from Schwann cells distributed along the peripheral nerves of intramedullary vessels; Due to the process of nerve crest occlusion in the fourth week of embryonic development, some ectopic Schwann cells According to the surgical and pathological results reported in the literature, the origin of intraspinal schwannoma may be multi-caused, rather than a single source, and there is no theory in the literature that has been generally accepted, nor can it be explained by the cervical spinal cord and adults
.

3.
2 Clinical manifestations

The disease occurs at all ages and has no gender difference
.
Intramedullary schwannoma is a benign tumor, the clinical manifestations of the patient have the characteristics of general intramedullary tumors, closely related to the location of the tumor, mostly causing upper motor neuron damage under the plane of the affected spinal cord, often pain, numbness, paralysis and other symptoms; There may also be no overt
motor neuron damage.
This patient showed a feeling of stepping on cotton on both lower limbs, which was a deep sensory impairment
caused by tumor.

3.
3 MRI image manifestations

Among the 71 patients with intraspinal schwannoma reviewed by Bernal-Garcia et al.
, 66% were located in the cervical spinal cord, 21.
9% were in the thoracic spinal cord, and 9.
3% were in the lumbar spinal cord; Among the 43 cases reported in China and this case, 22 cases in the cervical segment accounted for 52%, 14 cases in the thoracic segment accounted for 33%, and 6 cases in the lumbar spinal cord accounted for 14%, so intramedullary schwannomas are mainly seen in the cervical spinal cord
.

Reviewing the literature and the case data of this group, the author believes that MRI of intramedullary schwannoma is as follows: the tumor is a solid nodule or mass shadow with non-central growth in the spinal cord, mostly located in the dorsal or posterior lateral side of the spinal cord, most of which do not involve all the spinal cord, most of the lesions are small, no more than 3 vertebral segments; T1WI is mainly equal or slightly lower signal, T2WI and other or slightly higher signal, there may be cysticles, necrosis, syringomyelia, peripheral spinal cord edema, very few calcifications can be seen, after enhancement, the tumor parenchyma is more obvious and uniformly strengthened, and the boundary is clear and sharp
.

3.
4 Differential diagnosis

Intraspinal schwannomas need to be differentiated
from other intramedullary tumors.

(1) ependymoma: ependymoma is located in the center of the spinal cord, often occurring in the lower spinal cord, cones and filaments, the tumor is prone to bleeding, cystic changes, secondary syringomyelia formation, T2WI tumor around the common low-signal hemosiderin ring, enhance the tumor is uneven strengthening; The intraspinal schwannoma is a non-central growth, which tends to occur in the cervical cord, the lesion is small, often accompanied by spinal cord edema, no cases of bleeding have been reported, and the tumor is significantly evenly strengthened after enhancement, and the edges are sharp and clear
.

(2) Astrocytoma: the tumor grows expansively or invasively grows along the longitudinal axis of the spinal cord, the range is large, often involving multiple spinal cord segments or even the full length of the spinal cord, the tumor boundary is not clear, often cystic and secondary syringomyelia, the solid part of the tumor is irregular and significantly strengthened by enhanced scanning, and its boundary is not clear, which is obviously different
from the schwannoma in the spinal cord.

(3) Hemangioblastoma: tends to occur in the cervical segment and thoracic spinal cord, more common in young adults aged 20~30 years, most or completely cystic tumors, cystic change area can be very long, cystic area contains tumor wall nodules, the nodule is often located on the dorsal side of the sac, enhanced scanning appendage nodules significantly strengthened, relatively homogeneous, the realm is sharp, sometimes the wall nodules see signs of vascular flow empty, large cystic area with small nodular solid lesions is a typical feature of angioblastoma; In this case, preoperative MRI diagnosis of angioblastoma is possible, retrospective analysis, this case of small nodule lesions in the spinal cord is significantly strengthened, the degree is not as obvious as the angioblastoma wall nodules, no large range of cystic areas, around the lesion is seen in the spinal cord edema area, different from the angioblastoma cystic area
.

(4) Metastases: metastases generally have a history of clinical tumors, when a single metastases occur, the lesion is small, the signal is uneven, the surrounding edema is obvious, usually not combined with syringomyelia, the enhanced scanning tumor is obviously unevenly strengthened, and ring strengthening
may occur.

(5) Intraspinal lymphoma: often occurs in the thoracic segment, manifested as uniform or uneven swelling of the lesion spinal cord, with uneven slightly lower T1 and uneven slightly higher T2 signal, the lesion involves a wide range, can involve the corresponding vertebral body, lamina and pedicles, and the lesion spinal cord is slightly unevenly strengthened after enhancement, and a significantly strengthened mass or nodular foci
can be seen inside.
There may be necrotic cystic areas of varying sizes in the lesion spinal cord, and if it has edge enhancement, it indicates tumor invasion, syringomyelia is rare, and the vertebral body and appendages
have not been reported in the review literature in intraspinal schwannomas.

(6) Intraspinal tuberculosis tumor: clinically, intramedullary tuberculosis tumor mostly occurs in young and middle-aged patients, mostly with low-grade fever, night sweats, accelerated erythrocyte sedimentation rate and other tuberculosis poisoning symptoms, caseous necrosis is ring-shaped slightly higher signal, after enhancement is obviously ring-shaped strengthening, its internal necrosis is not strengthened
.

Although intraspinal schwannoma is rare, MRI has certain characteristics - the lesion is a solid nodule or mass that grows non-centrally in the spinal cord, the lesion is small, may be accompanied by spinal cord edema and cavitation, the enhanced solid lesion is more obvious and evenly strengthened, the boundary is clear, and the correct diagnosis can be made by MRI scanning and enhancement examination before surgery
.