Erini Makariou MD

Case History: 40-year-old man with low back pain, right lower extremity paraesthesias, and incontinence. He presents 10 days later with worsening pain.

The initial lumbar spine MRI shows a T1 isointense intradural extramedullary mass at the level of T11/T12 causing moderate cord compression. The mass is well circumscribed and solid, with a cystic central component. The mass has avid enhancement on post-gadolinium imaging. These findings are most consistent with a schwannoma, and this mass was pathologically proven to be a schwannoma after resection.

On the lumbar spine MRI 10 days later, the mass demonstrates mobility. The mass is now at the level of T12/L1, previously T11/T12. The later coronal images show a clockwise rotation of the mass, which is more horizontally oriented on the subsequent MRI. The imaging finds are consistent with a mobile schwannoma.

Mobile intradural extramedullary masses are a rare entity, schwannomas being the most common tumor types. Schwannomas are a benign tumor comprised of the cells of the peripheral nerve sheath. Mobile intradural extramedullary schwannomas have a male predominance with mean age of 49. These patients present with symptoms of cord and nerve root compression, including weakness, back pain, radiculopathy, gate disturbance, or incontinence. The most common location is the lumbar (65%), thoracolumbar (15%), thoracic (10%) spine, followed by thoracocervical (5%) and cervical (5%) spine. Symptoms have been noted to be position related, exacerbated by Valsalva maneuvers and relieved by laying supine. The mobility of the schwannomas may be associated with changes in intradural pressure, such as after myelography. Mobility of the tumor may pose a challenge to locating the tumor during surgery, which can be resolved by using intraoperative ultrasound.

1. Lee, Dong Yeob, and Hoon Jae Chung. "Mobile schwannoma of the cauda equina diagnosed by magnetic resonance imaging and magnetic resonance myelography: A case report and review of the literatures." 

2. Kim, Soo-Beom, Hyung-Seok Kim, Jee-Soo Jang, and Sang-Ho Lee. "Mobility of intradural extramedullary schwannoma at spine: report of three cases with literature review." 

Poll

Can you diagnose this patient with low back pain, right lower extremity paraesthesias, and incontinence?

Image IQ: 40-Year Old Man Presents With Low Back Pain

30-year-old female who presented with a three-week history of vertigo, episodic dysarthria, left lower-extremity weakness.

Imaging demonstrates peripherally isointense and internally hypointense T1 signal of the deep and subcortical white matter. They do not restrict diffusion.  SWI demonstrates no suggestion of hemorrhage or calcification.  The lesions are T2/FLAIR hyperintense with perilesional vasogenic edema and smooth peripheral enhancement.

Answer: B. Tumifactive Multiple Sclerosis


(A) The colloidal vescicular phase of neurocystercosis often shows perilesional edema and peripheral enhancement, but cystic fluid on T1 weighted images are usually hyperintense to CSF, and the scolex may be found within the cysts as an internal focus of eccentric enhancement. (3)

(C) Tuberculous Granulomas often exhibit perilesional vasogenic edema; however, the cystic lesions are isointense to gray matter.  They do not restrict diffusion, but do show peripheral enhancement. (4)

(D) Abscesses demonstrate T2 hyperintensity in along the periphery of the lesion and ring enhancement with surrounding vasogenic edema and ring enhancement; however, they restrict diffusion which is not present in this case and typically exhibit symptoms typical of infection not compatible with this patient presentation. (5)
 

Discussion:  Tumefactive Multiple Sclerosis



The typical appearance of multiple sclerosis, with preferential involvement of major white matter tracts in a periventricular distribution, affords a relatively straight forward diagnosis; however, the differential may be expanded when a demyelinating lesions manifests as a single, or occasionally multiple, large or tumefactive demyelinating lesion, and sometimes the diagnosis is only clinched after brain biopsy. Tumefactive demyelinating lesions are usually larger than 2 cm, usually single, and their imaging characteristics mimic neoplasms and infection.

The disease most commonly afflicts women, with an average age of 37 years. These lesions almost are only rarely associated with a recent infection or vaccination. These lesions are indistinguishable from multiple sclerosis plaques on pathology, demonstrating reactive astrocytes with infiltrated by foamy macrophages. Myelin breakdown occurs, with resultant lipid accumulation in significant quantities within the plaques. (1)

Tumefactive demyelinating lesions have been misinterpreted as gliomas on frozen section, with the correct diagnosis revealed only after an unnecessary resection or adjunct therapy. The following imaging characteristics of tumefactive demyelinating lesions may aid the radiologist in distinguishing this disease from other differential considerations:

Tumefactive demyelinating lesisons tend to be circumscribed lesions with little mass effect.

They are typically supratentorial and are centered in the white matter, although they may extend to the cortex.

Approximately 50% of cases demonstrate ringlike or open-ring enhancement, with the incomplete portion of a ring on the gray matter aspect of the lesion. The enhancing portion of the ring is felt to represent the leading edge of demyelination in the white matter.

They may demonstrate dilated veins that traverse the center of the lesion.

They exhibit decreased rCBV on perfusion.

They respond rapidly and well to corticosteroid therapy, and may even disappear.

The following imaging features to not specific for or do not aid in the diagnosis of tumefactive demyelinating lesions:

a. Corpus callosum involvement: Also included in the diagnosis for "butterfly lesions" for GBM and lymphoma.

b. Increased diffusion: Seen in brain abscesses and aggressive neoplasms.

c. MR Spectroscopy: Tumefactive demyelinating lesions demonstrate spectra identical to neoplastic processes. (1)

References:
1. American Journal of Radiology 2004; 182: 195-199
2. American Journal of Radiology 2009; 251: 467-475
3. RadioGraphics 2010; 30:1705–1719
4. RadioGraphics 2007; 27:1255–1273
5. RadioGraphics 2015; 35:1555–1562

Can you properly diagnose this 30-year-old female?

Image IQ: Patient with Vertigo, Episodic Dysarthria and Lower-Left Extremity Weakness

37-year-old female with contrast CT of the neck for evaluation of possible adenopathy.


Tonsillar hypertrophy or hyperplasia is a sequela of chronic or recurrent tonsillitis and may be an incidental imaging finding, as in this case. The imaging characteristics of tonsillar hypertrophy include enlargement of bilateral adenoidal, palatine, or lingual tonsils with absence of intra-tonsillar fluid collections or adjacent inflammatory stranding on non-contrast CT. Hypertrophied tonsils enhance less than in tonsillar inflammation on contrast CT. In addition, prominent tonsillar crypts with trapped air (Figure 1) or tonsilloliths secondary to prior infection or inflammation may be present. The former, which is well delineated in this case, should not be confused with tonsillar abscess.


Differential diagnoses for tonsillar enlargement include, but are not limited to, tonsillar hypertrophy, tonsillitis, tonsillar abscess, tonsillar retention cyst, tonsillar squamous cell carcinoma, and tonsillar non-Hodgkin’s lymphoma. Tonsillitis typically presents as bilateral tonsillar enlargement with hyperenhancement and tonsillar striations on contrast CT. Tonsillar abscess presents as often unilateral, enlarged tonsil (greater than 2 cm in size) with central low attenuation and peripheral rim enhancement as well as possible effacement of ipsilateral oral airway due to its space-occupying nature on contrast CT. Both of these entities are often associated with adjacent inflammatory stranding and/or reactive cervical adenopathy. Tonsillar retention cyst is likely a sequela of prior tonsillitis and is incidentally found on the imaging studies as discrete, focal tonsillar fluid without surrounding enhancement or edema. Lastly, malignancy involving the tonsils results in tonsillar enlargement. The imaging characteristics of tonsillar squamous cell carcinoma include unilateral, mildly enhancing, poorly circumscribed tonsillar mass associated with mucosal ulcer and malignant cervical adenopathy, commonly in ipsilateral Level II. Tonsillar non-Hodgkin’s lymphoma is another differential consideration and typically presents as unilateral, well circumscribed or invasive tonsillar mass associated with often large, non-necrotic cervical adenopathy.
 

Image IQ: Possible Adenopathy

A 41-year-old female with no significant history presents with a several month history of headache.


Axial MR images through the posterior fossa demonstrate a large, extra-axial mass in the cerebellopontine angle and prepontine cistern that has irregular, frond-like margins, isointense signal to CSF on T1-weighted and T2-weighted sequences, incomplete attenuation on FLAIR, restricted diffusion on DWI/ADC, and no enhancement on postcontrast sequences. Findings are most consistent with an epidermoid cyst.


Lesions of the cerebellopontine angle (CPA) are frequent, representing up to 10% of all intracranial tumors. Vestibular schwannomas and meningiomas account for 85%-90% of CPA masses. The third most common CPA mass is an epidermoid cyst.

Epidermoid cyst, also known as a primary cholesteatoma, is a congenital inclusion of ectodermal epithelial elements during neural tube closure. Lesion growth is due to accumulation of keratin and cholesterol produced from desquamation of its squamous epithelium lining. On CT (not depicted), epidermoid cysts are hypoattenuating, similar to that of CSF, with irregular, lobulated margins. On MR, epidermoid cysts are heterogeneous with a similar to slightly higher signal intensity than CSF on T1-weighted and T2-weighted sequences. When lesion signal intensity is very similar to CSF, FLAIR sequences are valuable as lesion conspicuity is increased due to incomplete attenuation. Occasionally, signal intensity may exceed that of brain parenchyma on T1-weighted sequences, the so-called “white epidermoid,” which is due to high triglyceride and fatty acid content. Minimal marginal enhancement can be seen after administration of gadolinium. High signal on DWI and low signal on ADC is characteristic. Diffusion weighted imaging is essential in postsurgical evaluation of recurrence.

Epidermoid cysts are benign masses with a broad range of ages at presentation (eg, 20-60 years). Most common signs and symptoms at presentation are sensorineuronal hearing loss, trigeminal neuralgia, facial neuralgia, and headache, all of which are typically present for several years before diagnosis. Complete surgical resection is curative. However, larger lesions have more significant surgical complications as they may be adherent to cranial nerves, arteries, and brainstem at time of operation.

Bonneville F, et al. Unusual lesions of the cerebellopontine angle: a segmental approach. 

41-year-old female presents with chronic headache.

Author | Erini Makariou MD

Articles

Image IQ: 40-Year Old Man Presents With Low Back Pain

Image IQ: Patient with Vertigo, Episodic Dysarthria and Lower-Left Extremity Weakness

Image IQ: Possible Adenopathy

Image IQ: 41-year-old Female with Chronic Headache