Category Archives: Aunt Mickeys

Aunt Mickey (They Look the Same until You Undress Them). Posterior Fossa Tumor or Something Else?

51-year-old male with no significant past medical history presented with 3+ months H/O intermittent dizziness, intermittent headaches, difficulty going down stairs and 3+ days H/O tingling and numbness on the right side of face, right hand and foot. MRI revealed increased T2 signal and swelling of the entire pons including the middle cerebellar peduncles with effacement/obliteration of the prepontine and CP angle cisterns. Center of the lesion was heterogeneously T2 hypointense and showed heterogeneous contrast enhancement, small focus of diffusion restriction, focal area of increased CBV and high choline to creatine ratio (2.18) & a tall lactate peak on MR spectroscopy. Differential diagnoses at this point included metastasis, high-grade glioma, lymphoma and sarcoid.

FIGURE 1

FLAIR

T2

Postcontrast

Perfusion image

DWI with ADC

Spectroscopy

These were our differential diagnoses. Do you want to add any other differential diagnosis?

CT scan of chest, abdomen and pelvis were done in search of primary tumor. On CT chest, there were bilateral asymmetric hilar adenopathy and lower lobe predominant nodular densities. The overall chest findings were not typical for sarcidosis. Bronchoscopy-guided biopsy of the hilar nodes revealed non-caseating granulomas. CT of the abdomen and pelvis were unremarkable.

A diagnosis of sarcoidosis was presumed and the patient was put on steroids. Patient got better clinically and an MRI after 5 days revealed significant improvement of the T2 signal abnormality and mass effect. There was no appreciable change in the size of the enhancing lesion. Patient was discharged home with the diagnosis of sarcoidosis and was advised to continue steroids.

FIGURE 2

T2

Post contrast

2 weeks later the patient came back with new onset diplopia as a result of left 6th nerve palsy. MRI at this point showed interval enlargement of the mass, FLAIR abnormality and enhancement. Central T2 hypointense area was more heterogeneous. At … Continue reading >>

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Aunt Mickey (They Look the Same until You Undress Them). Calvarial Metastases or Something Else?

A 59 year-old woman presented with an approximate one-year history of worsening sensory disturbances and pain in the right side of her scalp and face.  Her past medical history was otherwise unremarkable.  Part of her initial work-up involved imaging of the head, which revealed multiple lytic lesions of varying sizes throughout the skull.    An unenhanced CT was done (Figure 1), and several circumscribed lytic lesions of varying sizes were seen throughout the calvarium.  There was no periosteal reaction or sclerosis surrounding the lesions.  There were no intracranial lesions. The patient was referred to a neurosurgeon for biopsy because no underlying primary tumor was found.

Pre-operative CT

Figure 1 - Axial CT image of the head, bone windows, demonstrates lytic lesions in the posterior calvarium with thinning of the inner and outer tables.

She continued to have similar symptoms post-operatively that prompted MR imaging of the brain (Figure 2). The images demonstrate several well-demarcated lesions that were T1 hypointense and T2 hyperintense when compared to bone marrow, with severe thinning of the adjacent cortex.  No intracranial lesions were present.  A T1 hyperintense right subdural collection was due to the recent surgery.

Figure 2 - T1 (left) and T2 (right) weighted axial MR images of the brain demonstrate several calvarial lesions that are T1 hypointense and T2 hyperintense when compared to normal bone marrow.

The differential diagnosis for multiple lytic lesions in the adult skull includes primarily metastatic disease and multiple myeloma.  Others include epidermoids, burr holes and in children, the histiocytoses.

What is your diagnosis?  Are there other rare causes of lytic osseous lesions in the skull?

The patient underwent a right frontal skull biopsy.  Pathology revealed non-caseating granulomatous inflammation, consistent with sarcoidosis.

Sarcoidosis is a multisystemic inflammatory disorder of unknown cause that is best known for pulmonary, lymph node, and cutaneous involvement.  … Continue reading >>

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Aunt Mickey (They Look the Same until You Undress Them). Cavernous Sinus Tumor or Something Else?

A young male presented with progressive right sided cranial nerve palsies was diagnosed as having a cavernous sinus syndrome.  CT was done (Fig. 1) and showed a mass in the right cavernous sinus extending to the sphenoid sinus.  Note that the mass contained some flecks of calcium and remodeled adjacent bones.  At this point in time, the differential diagnosis included mainly a solid tumor (schwannoma, neurofibroma, meningioma, metastases [less like due to age and absence of primary tumor), lymphoma, and hemangioma).  MR imaging with contrast was obtained and a coronal T1 image (Fig. 2) demonstrated that the mass enhanced homogeneously and avidly (there was also ventricular dilatation).  Axial post Gd image (Fig. 3) showed similar findings with the anterior aspect of the lesion projecting into the region of the right spheno-ethmoidal recess.  Posteriorly, the expanded the cavernous sinus and had a small region of no contrast enhancement.  The differential diagnosis continued to be same.

Figures 1-3: Non contrast CT, coronal post Gd T1WI, and axial post Gd T1WI.

What is your diagnosis? What should you always consider when a lesion in a cavernous sinus is present?

The imaging studies were re-evaluated and due to the calcifications and the non-enhancing region the possibility of a partially thrombosed aneurysm of the ICA was considered.  An angiogram was done (Fig. 4).

Fig 4.  Nearly lateral 3D DSA view after injection of right ICA.

Giant aneurysms represent 5% of all intracranial ones; the prognosis is not good: mortality is 50-100% depending on location.  The most common type is saccular and they can be further subdivided into those that have concentric layers of clot in their walls and those do not.  In the first subtype, their growth is due to intramural re-bleeding and associated inflammation which also results in significant perilesional edema. When they bleed, … Continue reading >>

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Aunt Mickey (They Look the Same until You Undress Them). Meningioma or Something Else?

73 year old lady presented with six weeks history of odd behavior, increasing apathy, expressive aphasia, and mild headache. An MRI including diffusion and perfusion imaging was obtained. MRI revealed a T1 hypointense (to cortex) and slightly T2 hyperintense (to cortex) extra-axial mass in the left frontal region. There were multiple central T2 hyperintense areas. On post contrast T1 weighted sequence, there was intense enhancement of the mass except the central T2 hyperintense areas.There were prominent diffusion restriction and high rCBV in most parts of the tumor in diffusion and perfusion imaging respectively.

At this point, what is your diagnosis? Meningioma…… right?

Our pre-operative diagnosis was also meningioma. Only concern was that the diffusion restriction was little too much for a meningioma, even for a densely cellular anaplastic meningioma.

There were two surprises for us both from surgeons as well as from pathologists. When the surgeons opened the dura, the mass was intra-axial! When the pathologists saw the tumor under microscope, they found diffuse large B-cell lymphoma with very high proliferative index (90-95%) and officially they called it “Large B-cell lymphoma, diffuse, with high proliferative rate and intermediate features between Burkitt lymphoma and large cell lymphoma (WHO classification 2008)”.

This is a very interesting case because the tumor grew without following the ‘basic rules of neuroradiology’. Though the tumor arose from intra-axial compartment the way it enlarged and its internal morphology gave it a look of an extra-axial mass. This is not an uncommon dilemma of day to day neuroradiology practice. The best way to differentiate between pathologies at a given anatomic location is to execute a mental workout (I call it ‘Curé’s algorithm’) which is consisting of a) correct identification of the compartment from where … Continue reading >>

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Aunt Mickey (They Look the Same until You Undress Them). Meningioma or Something Else?

51 year old lady presented with headache and gait disturbances. An MRI including perfusion imaging was obtained. MRI revealed an extra-axial, dural based mass of the posterior fossa which was isointense to gray matter on T1 weighted sequence and hyperintense to gray matter on T2 weighted sequence. There was no diffusion restriction. On T2 weighted sequence, there was wedge shaped area of perilesional T2 hyperintensity extending transversely and superiorly to involve vermis. With contrast, the lesion showed intense homogenous enhancement. On perfusion study, there was considerable increase in rCBV. Preoperatively it was diagnosed as meningioma and the patient was scheduled for resection.

On surgery, the mass was encapsulated but the capsule was tightly adherent to the cerebellum. On histopathology, the tumor turned out to be a malignant fibrous histiocytoma (MFH) with 40% MIB-1 index.

MFH, the most common soft tissue sarcoma in adults, arises from fibroblasts, myofibroblasts or undifferentiated mesenchymal cells. Most patients are between 50 and 70 years old. Men are affected 2-3 times more commonly than women. Most MFHs arise de novo however, they can occur secondary to prior radiation, trauma, Paget’s disease, chronic osteomyelitis or benign bone tumors. MFH most commonly occurs in lower extremity. Head and neck area is involved up to 10% of cases.  In head neck, nasal cavity and paranasal sinuses are most commonly involved. It has variable appearances on CT and MRI. On CT, this is usually large lobulated sift tissue mass which is isodense to muscles with destruction/remodeling of adjacent bone. There may calcification in up to 5-20% of patients. On MRI, they are isointense to muscle on T1 weighted sequence and heterogeneously hyperintense on T2 weighted sequence. This tumor can have both solid and cystic component. Solid portion enhances intensely. Spontaneous hemorrhage is frequently seen and can obscure the primary tumor. … Continue reading >>

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Aunt Mickey (They Look the Same until You Undress Them). Carotid-Cavernous Fistula or Something Else?

A middle age woman presented with left progressive proptosis.  A contrast enhanced CT was done and showed enlargement of the left superior ophthalmic vein on the axial plane (see below).  A coronal image confirmed this abnormality and demonstrated that the extraocular muscles and retro-orbital fat had a normal appearance.

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Physical examination showed no chemosis, vision loss or cranial nerve palsies.  Because of this the patient was brought back for repeat contrast enhanced CT of the orbits with Valsalva maneuver.  This study showed mild additional enlargement of the already prominent left superior ophthalmic vein and also of the right sided one (see below).  The combination of imaging and clinical findings was thought to be most compatible with orbital varices.  The patient opted for conservative management.

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Orbital varices are hamartomas composed of slow flow, low pressure and thinned walled and distensible blood vessels.  As they communicate with the rest of the circulation, they enlarge with Valsava, bending or prone position, and coughing and straining.  They produce proptosis which may be painful and because they may bleed, their symptoms may become acutely exacerbated.  They may also erode adjacent bone.  Treatment is very difficult and is reserved for those with repeated hemorrhages, thrombosis, optic nerve compression and disfigurement.  Orbital vascular processes included in the differential diagnosis are carotid cavernous fistulas of both types and less likely, venous thrombosis.

In CC fistulas, the ipsilateral cavernous sinus may be enlarged particularly in the direct ones (see below).  Extra-ocular muscles may also be large and the retro-ocular fat may have a “dirty” appearance.  In most patients with direct CCFs, chemosis, decreased vision and cranial nerve palsies are present.  Acute thrombosis of the superior ophthalmic vein may present with symptoms that are similar to those of a direct CCF.  Indirect CCFs may have less acute symptoms and be … Continue reading >>

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Aunt Mickey (They Look the Same until You Undress Them). Lhermitte-Duclos or Something Else?

A young man presented with ataxia.  Brain contrast enhanced MRI was done including DWI and perfusion.  T2WI showed a mixed intensity lesion in the inferior right cerebellar hemisphere which contained some “dark stripes”.  DWI ADC map show restricted diffusion centrally.  After contrast the lesion enhanced in a striped fashion and perfusion showed low rCBV (see below).  Llermitte-Duclos disease was considered in the differential diagnosis.

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Further questioning of patient disclosed that the symptoms had had a sudden onset 7 days earlier.  The diagnosis of subacute infarction of the right posterior inferior cerebellar artery territory was considered as the most likely cause of the findings.  The patient was followed and repeat MRI three months later demonstrated only malacia and atrophy in the location.

Llermitte-Duclos disease (a.k.a. dysplastic gangliocytoma of the cerebellum) is the CNS hallmark of Cowden syndrome.  It is probably a malformative hamartoma of the cerebellum seen nearly exclusively in this syndrome.  The typical lesion has a “corduroy” or “tiger striped” appearance, does not enhance after contrast, has restricted diffusion (presumably due to its high cellularity), and normal-to-increased perfusion. MRS shows low NAA, decreased Cho/Cr, elevated lactate and high myoinositol and at times the spectra may be near normal (see below).  PET shows increased FDG accumulation.  Thus to differentiate it from an infarct with similar appearance perfusion and PET studies are best when in doubt.  Additionally, contrast enhancement in Llermitte-Duclos is extremely rare.

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Suggested readings:

Klish J, JUengling F, Spreer J, Koch D, et la. Llhermitte-Duclos disease: assessment with MR imaging, positron emission tomography, single photon emission CT, and MR spectroscopy. AJNR Am J Neuroradiol 2001; 22: 824-30

Moonis G, Ibrahim M, Melhem ER. Diffusion-weighted MRI in Llermitte-Duclos disease: report of two cases. Neuroradiology 2004; 46: 351-54

Awwad EE, Levy E, Martin DW, Merenda GO. Atypical MR appearance of Lhermitte-Duclos disease … Continue reading >>

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Aunt Mickey (They Look the Same until You Undress Them). Meningioma or Something Else?

A young African American woman presented with progressive left vision loss.  Brain MRI with contrast and perfusion studies were obtained.  The studies showed a dural-based lesion involving the lateral aspect of the left cavernous sinus which extended superiorly and crossed the planum sphenoidale to insinuate itself around the contralateral anterior clinoid process. The lesion was isointense to gray matter on T1WI, dark on T2WI, showed homogeneous gadolinium enhancement and increased rCBV on the perfusion images (see below).  The provisional diagnosis of meningioma was made and the patient scheduled for surgical decompression of left optic canal.

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Before surgery, a chest radiograph was obtained and showed bilateral hilar nodularities.  Surgery was postponed and a chest CT confirmed the hilar abnormalities and showed parenchymal abnormalities (see below).  Based on the findings a work up for sarcoidosis was performed and was positive.  The patient received steroids and her vision improved.  Follow-up brain MRI showed the lesion to be smaller.

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Sarcoidosis is more common in younger (average age: 35 years) African American women.  Over one half of patients will have neurological complaints, generally longstanding.  In about 10% of patients, sarcoidosis is isolated to the CNS.  The most common symptoms are headaches and cranial nerve palsies (mostly affecting the V, VII, VIII and III).  Approximately 15% of patients have dural disease (which is often accompanied by leptomeningeal involvement).  Dural disease responds well to treatment.  Conversely, intra-axial disease leads to seizures and is more difficult to control.  Angiotensin converting enzyme test is positive in 50% of patients.  The MRI findings on our case are typical of sarcoidosis.  The very low T2 signal can be seen in up 20% of meningiomas (particularly of the fibroblastic or transitional types).  Remember that most meningiomas are isointense to gray matter on T2WI (see below).

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Suggested readings:

Chirstoforidis GA, Spickler EM, Recio … Continue reading >>

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Aunt Mickey (They Look the Same until You Undress Them). Myxopapillary Ependymoma or Something Else?

This young male presented with chronic but progressive low back pain and lower extremity weakness.  MR imaging of the lumbar spine with contrast showed a lesion, intradural/extramedullary, extending from T12 to L4.  The lesion “expanded” the spinal canal and produced significant remodeling (scalloping) of the posterior vertebral bodies.  The mass had mostly low T1 signal pre contrast, mostly high T2 signal and enhanced after gadolinium.  Is it a large myxopapillary ependymoma?

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Analysis of axial images showed that the mass involved the spinal canal but extended out into the paraspinal regions, including the right psoas muscle, via several neural foramina.  The diagnosis was reconsidered to include giant invasive spinal schwannoma (histologically confirmed later).

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Schwannomas are the most common primary spinal tumor occurring predominantly in the cervical and thoracic regions.  Tumors of the cauda equina region represent only 6% of all spinal masses; most are schwannomas. “Giant” schwannomas are rare, long lesions that expand, remodel or destroy adjacent bones.  When they extend to extra-spinal myofascial planes, they are considered “invasive”.  Symptoms vary from severe to mild. Total excision is advocated but not always feasible.  Spinal fusion after tumor resection is needed in most patients.  Perhaps, fewer than 20 cases of giant schwannomas are found in the modern literature nearly all of them in the lumbosacral region. They are not associated with NF-2. The main differential diagnosis is that of myxopapillary ependymoma. Giant ependymomas are more common in younger individuals and despite attaining large size they do not tend to produce the focal bone scalloping and paraspinal involvement that giant schwannomas typically show (see illustration below). Mutiple schwannomas, as seen in NF-2 could also have a similar appearance.

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References:

Sridhar K, Ramamurthi R, Vasudevan MC, Ramamurthi B. Giant invasive spinal schwannomas: definiation and surgical management. J Neurosurg (Spine) 2001; 94: 210-215

Hung CH, … Continue reading >>

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Aunt Mickey (They Look the Same until You Undress Them). Subarachnoid Hemorrhage or Something Else?

A young female presented to an outside hospital with headache of one day duration. An MR brain study was done and interpreted as showing acute subarachnoid hemorrhage in the right temporal/occipital region.  The patient was transferred to our hospital for treatment and before performing a lumbar puncture a head CT was done.  The CT was interpreted as normal.  CSF was obtained and was also normal.

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Analysis of images showed an artifact involving the right lower side of the skull seen only on the DWI, ADC and a T2* sequence.  This magnetic susceptibility artifact was found out to have been due to a metal chain.  Upon arrival in our CT scanner, the technologists removed the chain to prevent artifacts.

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Discussion:

In FLAIR images, an inversion pulse is applied to suppress the normal signal intensity from CSF.  Multiple causes result in T2 prolongation of CSF signal making it bright on FLAIR and include: inhaled oxygen, increased proteins due to presence of blood or infection, tumor, propofol, and hyperdynamic pulsations such as those seen in the basilar cisterns particularly around arteries.  Artifacts resulting in hyperintense CSF include: motion, inhomogeneity in amplitude of initial inversion pulse, chemical shift, cross-talk, truncation, suboptimal inversion time, overlapping of imaging planes and as in this patient, magnetic susceptibility artifact.  Metals may result in incomplete nulling of CSF signal simulating hemorrhage or increased CSF proteins.  This is commonly seen in the frontal regions in patients with dental braces.

References:

  1. Cianfoni A, Martin MGM, Hesselink JR, et al. Artifact simulating subarachnoid and intraventricular hemorrhage on single-shot, fast spin-echo fluid-attenuated inversion recovery imaging caused by head movement: a trap for the unwary. AJNR Am J Neuroradiol 2006; 27: 843-849
  2. Tha KK, Terae S, Kudo K, Miyasaka K. Differential diagnosis of hyperintense cerebrospinal fluid on fluid-attenuated inversion recovery images of the brain.
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