Download MR Imaging of Perineural Spread of Malignancy - SCBT-MR

MR Imaging of Perineural Spread of Malignancy:
A Case-Based Imaging Review
Benjamin M. Howe M.D., Robert J. Spinner M.D., Mark A. Nathan M.D., Joel P. Felmlee Ph.D., Kimberly K. Amrami M.D.
Mayo Clinic Rochester, MN
Introduction:
Perineural spread of malignancy is well
known in head and neck tumors. It is also know to occur in
gastrointestinal malignancy such as pancreatic cancer. Perineural spread
of breast cancer is known to occur, but the diagnosis and MR imaging
may be challenging in the setting of prior surgery and/or radiation.
The post-gadolinium enhancement pattern is a critical factor when
attempting to differential malignant spread along the plexus from
radiation neuritis, or inflammatory neuropathies. Malignant plexus
involvement is classically described on MR imaging as having a nodular
appearance which is thought to represent small nodular foci of tumor
along the nerves. Enhancement in radiation neuritis is typically thin
smooth peripheral enhancement and in the chronic phase often has a
retractile and fibrotic appearance about the plexus. In addition to the
primary nerve findings, MR is an excellent modality for characterizing
muscle denervation and atrophy which are more common in the setting of
malignant invasion of the peripheral nerves. Thickening and
enhancement of the ipsilateral perirectal fascia is an additional finding
noticed in this small cohort of patients. It is possible this represents
tumor cells about the inferior hypogastric and splanchnic plexus
representing the pathway of disease spread.
.
Perineural spread of gastrointestinal and genitourinary malignancies are
less frequently discussed. Local perineural involvement is known to
occur in prostate and cervical cancer. In some cases, the perineural
involvement can spread to involve lumbosacral plexus and the sciatic
nerve.
The purpose of this educational poster is to review the clinical
presentation and imaging appearance of perineural spread of
genitourinary malignancies to the lumbosacral plexus and sciatic nerve.
We will discuss the anatomy that provides the pathway for spread and the
MR imaging and clinical features that help make this diagnosis.
Cases of perineural spread of pelvic malignancy will likely require a
biopsy for definitive diagnosis. Perineural spread of malignancy is
known to occur with “skip lesions” where normal segments of nerve are
located between areas of tumor deposition. MRI is a useful tool to
identify the point of maximal nerve abnormality in hopes of increasing
the diagnostic yield of the biopsy.
Anatomy:
The lumbosacral trunk is formed by the L4 and L5
nerves. The lumbosacral trunk converges with the sacral plexus (S1-S4)
to form the lumbosacral plexus.
The parasympathetic innervation of the pelvic organs occurs via the
splanchnic nerves from S2-S4. These splanchnic nerves coalesce with
the hypogastric nerves to form the inferior hypogastric plexus. The
inferior hypogastric plexus provides the innervation of the rectum and
bladder. It forms the uterovaginal plexus in females and the prostatic
plexus in males. The hypogastric plexus is a paired structure that lies
along the perirectal fascia.
Pathology:
Local perineural invasion is well described in
colorectal, cervical, and prostate cancer. Bastacky et al. reported
perineural invasion in 20% of prostate needles biopsies and reported a
relatively high specificity (96%) and low sensitivity (27%) in predicting
extracapsular extension of disease (The American journal of surgical
pathology 17.4 (1993): 336-341) . Subsequent studies of endorectal coil
MR imaging have demonstrated improved prediction of extracapsular
disease when compared to clinical and pathologic features alone.
(Radiology 2004; 232:133–139) The evaluation of localized extension
of disease is important in planning for nerve sparing operations for both
prostate cancer and malignancies of the uterus and cervix.
The vast majority of malignant disease in the pelvis with neurologic
involvement occurs from direct invasion from the tumor or local mass
affect. Rarely tumor can extend along the peripheral nerves and
propagate proximal and distal to the site of the initial tumor. In rare
cases, the tumor can spread to involve the lumbosacral plexus and sciatic
nerve.
Perineural spread of malignancy of rectal and genitourinary malignancies
can propagate to involve the entire lumbosacral plexus and sciatic nerve.
The proposed pathway to the sciatic nerve is:
Prostatic/utero
vaginal/vesical
/rectal plexus
Inferior
hypogastric
plexus
Splanchnic
plexus (S2S4)
Lumbosacral
plexus
Sciatic nerve
b.
a.
Case 1: A 61 year old man with perineural prostate cancer of the right sciatic nerve. Fat saturated
coronal oblique and axial SPGR images demonstrate thick peripheral nerve enhancement (arrow)
and ipsilateral perirectal fascial thickening (arrowheads).
Schematic of proposed pathway of perineural spread of prostate cancer to the sciatic nerve. By
permission of Mayo Foundation for Medical Education and Research. All rights reserved.
Clinical Presentation: In addition to common clinical
conditions such as lumbar spine disease and inflammatory neuropathies,
the differential diagnosis in cancer patients with neuropathy includes
radiation neuritis, chemotherapy induced neuropathy, and neuropathy
associated malignancy (extrinsic mass with compression or perineural
spread of disease). Radiating pain and weakness are clinical features that
raise suspicion for malignant involvement of the peripheral nerves.
Jaeckle et al. reviewed 85 patients with lumbosacral plexopathy
secondary to a pelvic tumor and found that pain was the dominant
clinical symptom (91%) and weakness the dominant clinical sign (86%).
(Neurology 35.1 (1985): 8-8) The clinical signs and symptoms of
perineural spread of malignancy in our small cohort of patients are
similar to larger studies of malignant lumbosacral plexopathy associated
with local direct invasion of the nerves by the primary tumor, such as
described by Jaeckle et al. In contrast to malignant disease, radiation
induced plexopathy classically presents with progressive sensory
symptoms. (Radiotherapy and Oncology Volume 105, Issue 3, December
2012, Pages 273–28 )
MR Imaging: MR imaging of the lumbosacral plexus is
preferred at 3 Tesla utilizing an 8 channel torso array coil. For the
evaluation of potential perineural spread of malignancy, the MR exam is
performed without and with intravenous gadolinium contrast. The noncontrast portion of the exam consists of T1 and T2-weighted fat-saturated
images performed in the axial plane and a coronal oblique plane to the
body of the sacrum. The axial image is performed with a field of view to
cover the entire pelvis while the coronal oblique images are performed
with a smaller field of view (24cm) from posterior to the sacrum to
anterior to the sciatic notch. Post gadolinium spoiled gradient recall
images with fat saturation are performed in the axial and coronal oblique
planes.
Case 2: A 61 year old woman with
perineural cervical cancer of the left sciatic
nerve. Fat saturated coronal oblique SPGR
image demonstrate thick peripheral nerve
enhancement (arrow) and ipsilateral
perirectal fascial thickening (arrowheads).
Cases/Conclusion: Five patients with gadolinium
contrast pelvic MRI and perineural malignancy on a sciatic nerve biopsy
were reviewed (Table). All patients had MR neural enhancement patterns
suggesting an infiltrative process. Four of the five patients had
ipsilateral perirectal fascial thickening which may represent the direct
pathway of spread from the pelvic tumor to the sciatic nerve.
MRI is a useful modality for identifying worrisome nerve enhancement
patterns and for planning is cases where biopsy is indicated. Pain was
the primary clinical symptom in these 5 patients. Perineural spread of
malignancy may occur many years after initial therapy as demonstrated
in our small cohort of patients.
Case 3: A 71 year old man with perineural
prostate cancer of the left sciatic nerve. Fat
saturated axial SPGR image demonstrates
thick peripheral nerve enhancement (arrow)
and ipsilateral perirectal fascial thickening
(arrowheads).
Biopsy proven cases of sciatic perineural spread of pelvic
malignancy
Presentation
after initial
surgery
Recurrent/Residual tumor
in operative bed on MRI
Cancer type
Presentation
Prostate
Pain followed by progressive
weakness and numbness
Prostate
Pain followed by numbness
and tingling
9 yrs.
No
Prostate
Pain and weakness
5 yrs.
Yes
Prostate
Pain followed by weakness
16 yrs.
Yes
Cervical
Pain and weakness
3 wks.
Yes
13 yrs.
No
Metastatic disease
Gadolinium
enhancement
Ipsilateral perirectal
fascial thickening
None (WB-BS, Skel.
Survey)
Nodular
peripheral
Yes
None (C-11 choline
CT/PET)
None (C-11 choline
CT/PET)
Yes (C-11 choline
PET/CT and WE-BS)
Unknown (advanced
local disease)
Thick irregular
peripheral
Yes
Fusiform
Yes
Thick peripheral
Yes
Thick peripheral
Yes