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279
Pictorial
Intrathoracic Correlation
Neurogenic
Tumors:
Essay
MR-Pathologic
Furnikazu Sakai,1 Shusuke Sone,1 Kunihiro Kiyono,1 Atsunori Maruyama,1 Hitoshi Ueda,1 Jun Aoki,1 Takashi Kawai,1 Keiko Ishii,2 Masami Morimoto,3 Masayuki Haniuda,3 and Tomonobu Koizumi4
An MR-pathologic
neurogenic two ganglioneuromas) was performed to characterize their MR appearances. The three types of intrathoracic neurogenic tumor were found to have characteristic appearances on MR images that should be helpful when establishing the differential diagnosis of posterior mediastinal tumors. The MR and histologic features of these tumors are illustrated and described in this essay.
tumors
(three
correlation
neurofibromas,
of nine intrathoracic
four schwannomas,
and
The multiplanar capability and high contrast resolution of enable precise definition of the location and extent of intrathoracic neurogenic tumors. The absence of artifacts on MR caused by high-density bone, which often compromise CT scans, facilitates clear visualization of the intracanalicular extension of neurogenic tumors in paraspinal regions. One report [1] has noted characteristic MR findings in paraspinal neurofibromas in patients with neurofibromatosis: that is, high MR
signal signal
intensity intensity
in the peripheral zone of the mass in the central zone on T2-weighted
and low images.
The high intensity was attributed to myxoid degeneration seen in pathologic specimens. Although a detailed CT-pathologic correlation of intrathoracic neurogenic tumors has been published [2], a detailed MR-pathologic correlation of intrathoracic neurogenic tumors is lacking. This prompted us to
Received January 1 Department of 2Department of 3Department of Department of AJR 159:279-283,
correlate
MR features
and histologic
resected
intrathoracic
neurogenic
Subjects
and Methods
Our study
group
rogenic tumors
comprised
findings
nine patients
(three neurofibromas,
with
1992 0361 -803X/92/1
592-0279
© American
Roentgen
intrathoracic
four schwannomas,
neu-
and two
ganglioneuromas). The group included seven women and two men. All three patients with neurofibromas had stigmata of neurofibromatosis. The remaining six patients with schwannomas or ganglioneuromas had no evidence of neurofibromatosis. All nine patients had no symptoms related to their tumors, and the mass lesions were incidental findings on their chest radiographs. All nine tumors were
resected,
and a pathologic
MR
were
images
diagnosis
obtained with WI) or a 0.5-T
was established. either a 1 .5-T (Signa, General (MRH-500, Hitachi Medical Co.
Electric, Milwaukee, Ltd., Tokyo, Japan) superconductive imaging unit with ECG gating and respiratory compensation. Ti -weighted spin-echo images (AR! 20-35 [TRITE]) and proton density-weighted and T2-weighted multiecho
images
(2-3
x
RR/20-35,
planes,
and Ti -weighted
sagittal
planes.
In two
images
neurofibromas,
70-80)
were
were
acquired three
acquired
in coronal
schwannomas,
in axial
and/or and
one
ganglioneuroma, Ti -weighted axial and coronal and/or sagittal images were obtained after IV injection of 0.1 mmol of gadopentetate dimeglumine per kilogram body weight.
8, 1992; accepted after revision February 28, 1992. Radiology, School of Medicine, Shinshu University, Asahi, Matsumoto, 390 Japan. Address reprint requests to F. Sakai. Laboratory Medicine, School of Medicine, Shinshu University, Asahi, Matsumoto, 390 Japan. Surgery, School of Medicine, Shinshu University, Asahi, Matsumoto, 390 Japan. Internal Medicine, School of Medicine, Shinshu University, Asahi, Matsurnoto, 390 Japan. August
in nine surgically
tumors.
Ray Society
SAKAI
280
In five tumors
neurofibromas, one schwannoma, and one of the resected specimens were obtained by using the 1 .5-T imaging unit or a 2.0-T chemical-shift imaging unit (General Electric, Fremont, CA). Ti-weighted (400-600/ ganglioneuroma),
Downloaded from www.ajronline.org by 122.54.193.100 on 10/14/15 from IP address 122.54.193.100. Copyright ARRS. For personal use only; all rights reserved
20) spin-echo
(three MR
images
images and T2-weighted
(2000-3000/80-120)
D
images
E Fig. 1-Vagal
neurofibroma
in a 57-year-old
ET AL.
were
AJR:159,
obtained
in axial and coronal
planes.
August 1992
The resected
specimens cx vivo MR images, and the pathologic findings in the specimens were compared with the corresponding MR images. In five tumors, MR images of resected specimens also were obtained to compare with
were cut in the same planes as those used to acquire
the
F
woman with neurofibromatosis.
A, Tl-weighted (769/20) axial MR image shows a mass lesion in superior portion of mediastinum. Peripheral zone (straight arrow) of mass has low signal intensity, and central zone (curved arrow) has intermediate signal intensity. B, T2-weighted (1538/80) axial MR image shows signal intensity of mass lesion is higher than that of fat in the peripheral zone (straight arrow). However, central zone (curved arrow) remains intermediate in intensity. Curvilinear or nodular low-intensity regions (arrowheads) are noted along boundary of central area and peripheral zone of mass. C, Gadopentetate dimeglumine-enhanced Ti-weighted (769/20) axial MR image shows remarkable contrast enhancement in central zone (curved arrow) of mass. D, T2-weighted (2000/80) MR image of resected specimen shows peripheral zone (straight arrows) has a higher signal intensity than does central zone (curved arrows). Curvilinear or nodular low-intensity regions (arrowheads) are noted along boundary of central and peripheral zones. E, Cut surface of gross specimen shows peripheral zone of resected mass has a gelatinous appearance (straight arrows) and central zone appears solid and yellowish (curved arrows). Nodular or linear whitish areas (arrowheads) are seen predominantly along boundary of central and peripheral zones. F, Photomicrograph shows peripheral zone (straight arrows) has myxoid degeneration with scanty cellular components. Central area (curved arrow) has packed cellular components and xanthomatous changes. Linear and nodular areas of collagenous fibrous tissues (arrowheads) are seen, mainly
along boundary of central area and peripheral zone. (Azan-Mallory
stain)
AJR:159,
preoperative tion
of
INTRATHORACIC
August 1992
MR images.
signal
intensity,
In the evaluation high
intensity
of MR images was
and descripequal to or as between the inten-
defined
greater than that of fat, intermediate intensity sities of fat and skeletal muscle, and low intensity
Downloaded from www.ajronline.org by 122.54.193.100 on 10/14/15 from IP address 122.54.193.100. Copyright ARRS. For personal use only; all rights reserved
than
the
intensity
of skeletal
NEUROGENIC
as
as equal to or less
muscle.
Results Neurofibroma
The three neurofibromas showed low to intermediate signal intensity on Ti-weighted images with a slightly higher signal intensity in the central zone than in the peripheral zone (Fig. 1A). On T2-weighted images, the peripheral zone showed a higher intensity than fat and the central zone remained of intermediate intensity, with regional curvilinear or nodular low intensities
along
the boundaries
of the central
Fig. 2.-Paraspinal schwannoma in a 68-yearold woman. A, TI-weighted (857/20) axial MR image shows a mass lesion with intermediate signal intensity in paraspinal region. Central portion (short arrow) of mass has a somewhat lower intensity than does peripheral portion (long arrow). B, T2-weighted (2571/80) coronal MR image shows signal intensity of central portion (black arrow) of mass lesion is higher than that of peripheral portion (white arrow). Peripheral por-
tion gions.
includes Linear
several
small
low intensity
des central high-intensity
high-Intensity (arrowheads)
reencir-
portion.
C, Cut surface of resected specimen shows a large region of unilocular cystic degeneration (arrow) in mass lesion. This corresponds to central high-intensity region seen on T2-weighted MR images. Collagenous fibrous layer encircles cystic region (arrowheads). D, Photomicrograph shows foci of cystic degeneration scattered in tumor (arrows). (AzanMallory stain)
and peripheral
TUMORS
281
zones (Fig. 1 B). On contrast-enhanced MR images, enhancement was seen in the central zones (Fig. 1C). At surgery, two of three neurofibromas were seen to arise from the vagus nerves, whereas the remaining neurofibroma arose from a thoracic spinal nerve root with extension into the spinal canal through an intervertebral foramen. Correlative study of T2-weighted images of the resected specimens and macroscopic findings disclosed that peripheral high-intensity zones on T2-weighted images corresponded to gelatinous regions, and central zones of intermediate intensity corresponded to solid tissue regions (Figs. 1 D and 1 E). Microscopically, the peripheral gelatinous regions showed myxoid degeneration and the central solid regions showed packed nerve sheath cells and fibrous tissues with xanthomatous changes (Fig. iF). The curvilinear or nodular whitish areas seen on T2weighted images between the central and peripheral zones were composed of collagenous fibrous tissue (Fig. iF).
282
SAKAI
ET AL.
AJA:159,
,
.
.
August
1992
.‘
‘4 .:‘
,‘
,:
#{149}.
Downloaded from www.ajronline.org by 122.54.193.100 on 10/14/15 from IP address 122.54.193.100. Copyright ARRS. For personal use only; all rights reserved
.
,
-
I
.4#{149}..,._’
Fig. 3.-Paraspinal schwannoma in a 56-year-old woman. A, Ti-weighted (779/20) axial MR image shows round mass lesion with intermediate signal intensity in paraspinal region. B, T2-weighted (1667/80) axial MR image shows signal intensity of mass is inhomogeneously high. C, Tumor was resected transcervically and divided into several pieces. Photomicrograph of resected specimen shows tumor type A (thin arrows) and type B (thick arrow) areas with very little cystic degeneration. (H and E, original magnification x40)
Schwannoma
Schwannomas showed low to intermediate signal intensity on Ti -weighted images (Figs. 2A and 3A). On T2-weighted images, they showed inhomogeneously high intensity (Figs. 2B and 3B). Two of four schwannomas showed very highintensity regions within the tumor (Fig. 2B). They were found to be of paraspinal origin at surgery. Very high-intensity regions seen on T2-weighted images of two schwannomas corresponded
to cystic
degeneration
with surrounding
collag-
enous fibrous tissue (Figs. 2C and 2D). Two schwannomas that lacked very high-intensity regions on T2-weighted images lacked foci of cystic degeneration on histopathologic specimens (Fig. 3C). Ganglioneuroma
The two ganglioneuromas intermediate
signal
showed
intensity
relatively
on Ti -weighted
homogeneous images
(Fig. 4A).
changes
also may occur
pathologic
findings
of neurofibromas
both Ti - and T2-weighted
intensity
was
noted
on
images (Figs. 4A and 4B). Coronal
MR images clearly showed intracanalicular 4C). At surgery, both ganglioneuromas
extension
(Fig.
had a paraspinal origin. The cut surface of the ganglioneuromas showed a whorled appearance, which correlated well with MR images (Figs. 4D and 4E). Ganglion cells, nerve sheath cells, and nerve fibers were seen on microscopic specimens (Fig. 4F). Areas of curvilinear or nodular low intensities on MR images corresponded to collagenous fibrous tissue on pathologic specimens (Fig. 4F). Discussion Neurogenic
the thorax.
tumors
of various
Neurofibromas
histologic
may manifest
types
may arise in
as solitary
tumors
in schwannomas.
Ganglioneuromas
are composed of large ganglion cells, nerve sheath cells, and nerve fibers. Ganglioneuromas show a typical trabeculated or whorled appearance macroscopically on the cut surface [4]. Our study shows that MR findings correlate well with
curvilinear
of low
Antoni
variable degrees of myxoid degeneration [3, 4]. Schwannomas arise from nerve sheath cells and occur less commonly than neurofibromas in patients with neurofibromatosis. Schwannomas are divided histologically into two types: Antoni type A shows compactly packed nerve sheath cells, sometimes with palisading of tumor cells, Antoni type B shows scattered tumor cells within myxoid matrices [3, 4]. Both types may be present in a single schwannoma [3]. Inadequate blood supply to the center of the tumor sometimes causes cystic degeneration or hyalinization. Xanthomatous
T2-weighted
bands
has alternating
or may be one manifestation of neurofibromatosis. Histologically, neurofibromas show proliferation of nerve sheath cells interspersed with thick wavy collagen bundles and may show
On T2-weighted images, the signal intensity was inhomogeneously high (Fig. 4B). A whorled appearance caused by or nodular
..
H’’:.’::.p’.’.
‘.
reported signal
of intrathoracic
images,
neurogenic
high-intensity
corresponded
regions to myxoid
by Burk et al. [1 ]. Curvilinear intensity
corresponded
tumors.
On
in the periphery degeneration,
or nodular
to collagenous
as
areas of low
fibrous
tissue.
These fibrous tissues were arranged along the boundaries between the central and peripheral zones in the three neurofibromas. The inhomogeneously high-intensity appearance of schwannomas on T2-weighted images corresponded to alternating
Antoni
A and B areas.
A central
very
high-intensity
region on T2-weighted images of schwannomas corresponded to areas of cystic degeneration. The two ganglioneuromas showed a whorled appearance on MR that corresponded to intermingled neural tissues and collagenous fibrous tissues on histopathologic specimens. Because our observations are based on a limited number of patients, the true further investigation.
specificity However,
of these MR findings awaits some of the patterns seen on
Downloaded from www.ajronline.org by 122.54.193.100 on 10/14/15 from IP address 122.54.193.100. Copyright ARRS. For personal use only; all rights reserved
AJR:159,
August
INTRATHORACIC
1992
D
NEUROGENIC
TUMORS
E
283
F
Fig. 4.-Paraspinal ganglioneuroma in a 17-year-old girl. A, TI-weighted (857/20) axial MR image shows intermediate-intensity mass in paraspinal B, T2-weighted (1714/80) axial MR image shows curvilinear or nodular low-intensity
region with curvilinear low-intensity areas (arrowheads). areas (arrowheads) within high-intensity mass, which
has
a
somewhat whorled appearance. C, Ti-weighted (857/20) coronal MR image shows mass lesion extends into spinal canal through an intervertebral foramen (arrow). D, T2-weighted (2500/100) MR image of resected specimen shows a whorled appearance caused by curvilinear or nodular bands of low intensity (arrowheads). E, On cut surface F, Photomicrograph
MR images
of intrathoracic
may
of resected specimen, same whorled appearance shows curvilinear ares of collagenous fibrous
prove
to be characteristic
neurogenic
of various
is seen. tissue (arrowheads)
within
tumor.
(H and E)
types
tumors.
REFERENCES 1. Burk DL Jr, Brunberg JA, Kanal E, Latchaw RE, Wolf GL. Spinal and paraspinal neurofibromatosis. Radiology 1987;162:797-801
2. Cohen LM, Schwartz AM, Rockoff SD. Benign schwannomas: pathologic basis for CT inhomogeneities. AJR 1986;147: 141 -1 43 3. Harkin JC, Reed AJ. Tumors of the peripheral nervous system. In: Atlas of tumor pathology, 2nd series, fascicle 3. Washington, DC: Armed Forces Institute of Pathology, 1969:29-96 4. Enzinger FM, Weiss SW. Soft tissue tumors, 2nd ed. St. Louis: Mosby, 1983
279
Pictorial
Intrathoracic Correlation
Neurogenic
Tumors:
Essay
MR-Pathologic
Furnikazu Sakai,1 Shusuke Sone,1 Kunihiro Kiyono,1 Atsunori Maruyama,1 Hitoshi Ueda,1 Jun Aoki,1 Takashi Kawai,1 Keiko Ishii,2 Masami Morimoto,3 Masayuki Haniuda,3 and Tomonobu Koizumi4
An MR-pathologic
neurogenic two ganglioneuromas) was performed to characterize their MR appearances. The three types of intrathoracic neurogenic tumor were found to have characteristic appearances on MR images that should be helpful when establishing the differential diagnosis of posterior mediastinal tumors. The MR and histologic features of these tumors are illustrated and described in this essay.
tumors
(three
correlation
neurofibromas,
of nine intrathoracic
four schwannomas,
and
The multiplanar capability and high contrast resolution of enable precise definition of the location and extent of intrathoracic neurogenic tumors. The absence of artifacts on MR caused by high-density bone, which often compromise CT scans, facilitates clear visualization of the intracanalicular extension of neurogenic tumors in paraspinal regions. One report [1] has noted characteristic MR findings in paraspinal neurofibromas in patients with neurofibromatosis: that is, high MR
signal signal
intensity intensity
in the peripheral zone of the mass in the central zone on T2-weighted
and low images.
The high intensity was attributed to myxoid degeneration seen in pathologic specimens. Although a detailed CT-pathologic correlation of intrathoracic neurogenic tumors has been published [2], a detailed MR-pathologic correlation of intrathoracic neurogenic tumors is lacking. This prompted us to
Received January 1 Department of 2Department of 3Department of Department of AJR 159:279-283,
correlate
MR features
and histologic
resected
intrathoracic
neurogenic
Subjects
and Methods
Our study
group
rogenic tumors
comprised
findings
nine patients
(three neurofibromas,
with
1992 0361 -803X/92/1
592-0279
© American
Roentgen
intrathoracic
four schwannomas,
neu-
and two
ganglioneuromas). The group included seven women and two men. All three patients with neurofibromas had stigmata of neurofibromatosis. The remaining six patients with schwannomas or ganglioneuromas had no evidence of neurofibromatosis. All nine patients had no symptoms related to their tumors, and the mass lesions were incidental findings on their chest radiographs. All nine tumors were
resected,
and a pathologic
MR
were
images
diagnosis
obtained with WI) or a 0.5-T
was established. either a 1 .5-T (Signa, General (MRH-500, Hitachi Medical Co.
Electric, Milwaukee, Ltd., Tokyo, Japan) superconductive imaging unit with ECG gating and respiratory compensation. Ti -weighted spin-echo images (AR! 20-35 [TRITE]) and proton density-weighted and T2-weighted multiecho
images
(2-3
x
RR/20-35,
planes,
and Ti -weighted
sagittal
planes.
In two
images
neurofibromas,
70-80)
were
were
acquired three
acquired
in coronal
schwannomas,
in axial
and/or and
one
ganglioneuroma, Ti -weighted axial and coronal and/or sagittal images were obtained after IV injection of 0.1 mmol of gadopentetate dimeglumine per kilogram body weight.
8, 1992; accepted after revision February 28, 1992. Radiology, School of Medicine, Shinshu University, Asahi, Matsumoto, 390 Japan. Address reprint requests to F. Sakai. Laboratory Medicine, School of Medicine, Shinshu University, Asahi, Matsumoto, 390 Japan. Surgery, School of Medicine, Shinshu University, Asahi, Matsumoto, 390 Japan. Internal Medicine, School of Medicine, Shinshu University, Asahi, Matsurnoto, 390 Japan. August
in nine surgically
tumors.
Ray Society
SAKAI
280
In five tumors
neurofibromas, one schwannoma, and one of the resected specimens were obtained by using the 1 .5-T imaging unit or a 2.0-T chemical-shift imaging unit (General Electric, Fremont, CA). Ti-weighted (400-600/ ganglioneuroma),
Downloaded from www.ajronline.org by 122.54.193.100 on 10/14/15 from IP address 122.54.193.100. Copyright ARRS. For personal use only; all rights reserved
20) spin-echo
(three MR
images
images and T2-weighted
(2000-3000/80-120)
D
images
E Fig. 1-Vagal
neurofibroma
in a 57-year-old
ET AL.
were
AJR:159,
obtained
in axial and coronal
planes.
August 1992
The resected
specimens cx vivo MR images, and the pathologic findings in the specimens were compared with the corresponding MR images. In five tumors, MR images of resected specimens also were obtained to compare with
were cut in the same planes as those used to acquire
the
F
woman with neurofibromatosis.
A, Tl-weighted (769/20) axial MR image shows a mass lesion in superior portion of mediastinum. Peripheral zone (straight arrow) of mass has low signal intensity, and central zone (curved arrow) has intermediate signal intensity. B, T2-weighted (1538/80) axial MR image shows signal intensity of mass lesion is higher than that of fat in the peripheral zone (straight arrow). However, central zone (curved arrow) remains intermediate in intensity. Curvilinear or nodular low-intensity regions (arrowheads) are noted along boundary of central area and peripheral zone of mass. C, Gadopentetate dimeglumine-enhanced Ti-weighted (769/20) axial MR image shows remarkable contrast enhancement in central zone (curved arrow) of mass. D, T2-weighted (2000/80) MR image of resected specimen shows peripheral zone (straight arrows) has a higher signal intensity than does central zone (curved arrows). Curvilinear or nodular low-intensity regions (arrowheads) are noted along boundary of central and peripheral zones. E, Cut surface of gross specimen shows peripheral zone of resected mass has a gelatinous appearance (straight arrows) and central zone appears solid and yellowish (curved arrows). Nodular or linear whitish areas (arrowheads) are seen predominantly along boundary of central and peripheral zones. F, Photomicrograph shows peripheral zone (straight arrows) has myxoid degeneration with scanty cellular components. Central area (curved arrow) has packed cellular components and xanthomatous changes. Linear and nodular areas of collagenous fibrous tissues (arrowheads) are seen, mainly
along boundary of central area and peripheral zone. (Azan-Mallory
stain)
AJR:159,
preoperative tion
of
INTRATHORACIC
August 1992
MR images.
signal
intensity,
In the evaluation high
intensity
of MR images was
and descripequal to or as between the inten-
defined
greater than that of fat, intermediate intensity sities of fat and skeletal muscle, and low intensity
Downloaded from www.ajronline.org by 122.54.193.100 on 10/14/15 from IP address 122.54.193.100. Copyright ARRS. For personal use only; all rights reserved
than
the
intensity
of skeletal
NEUROGENIC
as
as equal to or less
muscle.
Results Neurofibroma
The three neurofibromas showed low to intermediate signal intensity on Ti-weighted images with a slightly higher signal intensity in the central zone than in the peripheral zone (Fig. 1A). On T2-weighted images, the peripheral zone showed a higher intensity than fat and the central zone remained of intermediate intensity, with regional curvilinear or nodular low intensities
along
the boundaries
of the central
Fig. 2.-Paraspinal schwannoma in a 68-yearold woman. A, TI-weighted (857/20) axial MR image shows a mass lesion with intermediate signal intensity in paraspinal region. Central portion (short arrow) of mass has a somewhat lower intensity than does peripheral portion (long arrow). B, T2-weighted (2571/80) coronal MR image shows signal intensity of central portion (black arrow) of mass lesion is higher than that of peripheral portion (white arrow). Peripheral por-
tion gions.
includes Linear
several
small
low intensity
des central high-intensity
high-Intensity (arrowheads)
reencir-
portion.
C, Cut surface of resected specimen shows a large region of unilocular cystic degeneration (arrow) in mass lesion. This corresponds to central high-intensity region seen on T2-weighted MR images. Collagenous fibrous layer encircles cystic region (arrowheads). D, Photomicrograph shows foci of cystic degeneration scattered in tumor (arrows). (AzanMallory stain)
and peripheral
TUMORS
281
zones (Fig. 1 B). On contrast-enhanced MR images, enhancement was seen in the central zones (Fig. 1C). At surgery, two of three neurofibromas were seen to arise from the vagus nerves, whereas the remaining neurofibroma arose from a thoracic spinal nerve root with extension into the spinal canal through an intervertebral foramen. Correlative study of T2-weighted images of the resected specimens and macroscopic findings disclosed that peripheral high-intensity zones on T2-weighted images corresponded to gelatinous regions, and central zones of intermediate intensity corresponded to solid tissue regions (Figs. 1 D and 1 E). Microscopically, the peripheral gelatinous regions showed myxoid degeneration and the central solid regions showed packed nerve sheath cells and fibrous tissues with xanthomatous changes (Fig. iF). The curvilinear or nodular whitish areas seen on T2weighted images between the central and peripheral zones were composed of collagenous fibrous tissue (Fig. iF).
282
SAKAI
ET AL.
AJA:159,
,
.
.
August
1992
.‘
‘4 .:‘
,‘
,:
#{149}.
Downloaded from www.ajronline.org by 122.54.193.100 on 10/14/15 from IP address 122.54.193.100. Copyright ARRS. For personal use only; all rights reserved
.
,
-
I
.4#{149}..,._’
Fig. 3.-Paraspinal schwannoma in a 56-year-old woman. A, Ti-weighted (779/20) axial MR image shows round mass lesion with intermediate signal intensity in paraspinal region. B, T2-weighted (1667/80) axial MR image shows signal intensity of mass is inhomogeneously high. C, Tumor was resected transcervically and divided into several pieces. Photomicrograph of resected specimen shows tumor type A (thin arrows) and type B (thick arrow) areas with very little cystic degeneration. (H and E, original magnification x40)
Schwannoma
Schwannomas showed low to intermediate signal intensity on Ti -weighted images (Figs. 2A and 3A). On T2-weighted images, they showed inhomogeneously high intensity (Figs. 2B and 3B). Two of four schwannomas showed very highintensity regions within the tumor (Fig. 2B). They were found to be of paraspinal origin at surgery. Very high-intensity regions seen on T2-weighted images of two schwannomas corresponded
to cystic
degeneration
with surrounding
collag-
enous fibrous tissue (Figs. 2C and 2D). Two schwannomas that lacked very high-intensity regions on T2-weighted images lacked foci of cystic degeneration on histopathologic specimens (Fig. 3C). Ganglioneuroma
The two ganglioneuromas intermediate
signal
showed
intensity
relatively
on Ti -weighted
homogeneous images
(Fig. 4A).
changes
also may occur
pathologic
findings
of neurofibromas
both Ti - and T2-weighted
intensity
was
noted
on
images (Figs. 4A and 4B). Coronal
MR images clearly showed intracanalicular 4C). At surgery, both ganglioneuromas
extension
(Fig.
had a paraspinal origin. The cut surface of the ganglioneuromas showed a whorled appearance, which correlated well with MR images (Figs. 4D and 4E). Ganglion cells, nerve sheath cells, and nerve fibers were seen on microscopic specimens (Fig. 4F). Areas of curvilinear or nodular low intensities on MR images corresponded to collagenous fibrous tissue on pathologic specimens (Fig. 4F). Discussion Neurogenic
the thorax.
tumors
of various
Neurofibromas
histologic
may manifest
types
may arise in
as solitary
tumors
in schwannomas.
Ganglioneuromas
are composed of large ganglion cells, nerve sheath cells, and nerve fibers. Ganglioneuromas show a typical trabeculated or whorled appearance macroscopically on the cut surface [4]. Our study shows that MR findings correlate well with
curvilinear
of low
Antoni
variable degrees of myxoid degeneration [3, 4]. Schwannomas arise from nerve sheath cells and occur less commonly than neurofibromas in patients with neurofibromatosis. Schwannomas are divided histologically into two types: Antoni type A shows compactly packed nerve sheath cells, sometimes with palisading of tumor cells, Antoni type B shows scattered tumor cells within myxoid matrices [3, 4]. Both types may be present in a single schwannoma [3]. Inadequate blood supply to the center of the tumor sometimes causes cystic degeneration or hyalinization. Xanthomatous
T2-weighted
bands
has alternating
or may be one manifestation of neurofibromatosis. Histologically, neurofibromas show proliferation of nerve sheath cells interspersed with thick wavy collagen bundles and may show
On T2-weighted images, the signal intensity was inhomogeneously high (Fig. 4B). A whorled appearance caused by or nodular
..
H’’:.’::.p’.’.
‘.
reported signal
of intrathoracic
images,
neurogenic
high-intensity
corresponded
regions to myxoid
by Burk et al. [1 ]. Curvilinear intensity
corresponded
tumors.
On
in the periphery degeneration,
or nodular
to collagenous
as
areas of low
fibrous
tissue.
These fibrous tissues were arranged along the boundaries between the central and peripheral zones in the three neurofibromas. The inhomogeneously high-intensity appearance of schwannomas on T2-weighted images corresponded to alternating
Antoni
A and B areas.
A central
very
high-intensity
region on T2-weighted images of schwannomas corresponded to areas of cystic degeneration. The two ganglioneuromas showed a whorled appearance on MR that corresponded to intermingled neural tissues and collagenous fibrous tissues on histopathologic specimens. Because our observations are based on a limited number of patients, the true further investigation.
specificity However,
of these MR findings awaits some of the patterns seen on
Downloaded from www.ajronline.org by 122.54.193.100 on 10/14/15 from IP address 122.54.193.100. Copyright ARRS. For personal use only; all rights reserved
AJR:159,
August
INTRATHORACIC
1992
D
NEUROGENIC
TUMORS
E
283
F
Fig. 4.-Paraspinal ganglioneuroma in a 17-year-old girl. A, TI-weighted (857/20) axial MR image shows intermediate-intensity mass in paraspinal B, T2-weighted (1714/80) axial MR image shows curvilinear or nodular low-intensity
region with curvilinear low-intensity areas (arrowheads). areas (arrowheads) within high-intensity mass, which
has
a
somewhat whorled appearance. C, Ti-weighted (857/20) coronal MR image shows mass lesion extends into spinal canal through an intervertebral foramen (arrow). D, T2-weighted (2500/100) MR image of resected specimen shows a whorled appearance caused by curvilinear or nodular bands of low intensity (arrowheads). E, On cut surface F, Photomicrograph
MR images
of intrathoracic
may
of resected specimen, same whorled appearance shows curvilinear ares of collagenous fibrous
prove
to be characteristic
neurogenic
of various
is seen. tissue (arrowheads)
within
tumor.
(H and E)
types
tumors.
REFERENCES 1. Burk DL Jr, Brunberg JA, Kanal E, Latchaw RE, Wolf GL. Spinal and paraspinal neurofibromatosis. Radiology 1987;162:797-801
2. Cohen LM, Schwartz AM, Rockoff SD. Benign schwannomas: pathologic basis for CT inhomogeneities. AJR 1986;147: 141 -1 43 3. Harkin JC, Reed AJ. Tumors of the peripheral nervous system. In: Atlas of tumor pathology, 2nd series, fascicle 3. Washington, DC: Armed Forces Institute of Pathology, 1969:29-96 4. Enzinger FM, Weiss SW. Soft tissue tumors, 2nd ed. St. Louis: Mosby, 1983
