Radiology and Pathology
Teaching Points
Sessions I and II
Pat Hudgins and Dan Brat
I.1: Golden Grapes
I – Case 1
A single image says it ALL!
• Swollen edematous ON
– T2 information
• Expanded ON sheath
– Good old symmetry!
• Dirty intraconal fat
– Use of fat sat (FS) info
• Lack of flow void in SOV
– MR physics: moving spins
should give signal void
I – Case 1
Diffusion Weighted Imaging (DWI)
• Add diffusion gradients
• ↑ signal intensity (SI)
– Real: √ ADC map
– Artifact: T2 shine
through
• ADC map – dark
• True restricted diffusion
I – Case 1
Diffusion Weighted Imaging (DWI)
•
•
•
•
•
•
•
Infarcted brain
Pus
Rare acute MS plaque
Some high grade BT’s
Some neoplasms
Creuztfelt Jakob
Misc infections
• “Pus” is THE SHORTEST
pathologic diagnosis (Purulent
material is more appropriate)
• Stains for bacteria are NOT
helpful for speciation
• When infectious disease is on
the differential, specimen
should be sent to Microbiology
for cultures
I.2: Ain’t No Sunshine When You are Gone!
I – Case 2
“T1 Ax Gd FS “
I – Case 2
Imaging Techniques
Pulse Sequence “Families”
Spin Echo
Gradient Echo
I – Case 2
Fast Imaging Techniques
Siemens
MP-RAGE
VIBE
General Electric 3D Fast SPGR
LAVA-XV
Philips
THRIVE
3D TFE
I – Case 2
Fast Imaging Techniques
Gradient Echo – “Fast” Imaging
MP-RAGE
Magnetization Prepared Rapid
Acquisition Gradient Echo
• 3 D, can do multiplanar
reformats
• Isovoxel 1 mm x 1 mm x 1 mm
I – Case 2
Fast Imaging Techniques
Gradient Echo – “Fast” Imaging
Might look like a T1, but be careful
Disadvantages
• Metal artifact is bad
• WM very bright – can obscure
enhancing lesions
• Cranial nerves often “enhance”
Pilocytic Astrocytomas (grade
I) involve the optic
pathways more frequently
than Infiltrative
Astrocytomas (grades II-IV)
Anaplastic Astrocytoma
(grade III) differs from grade
II by the presence of
mitoses and from
Glioblastoma (grade IV) by
its lack of necrosis.
Anaplastic Astrocytoma is
generally fatal within 2-5
years.
I.3: Some Orbital Confusion
I – Case 3
Initial MRI: T1 A and C
• Do we see Stuff or a
Thing?
• Diff Dx for Stuff:
– Pseudotumor
– Infection (but fat clean)
– Sarcoid
– Lymphoma
– We’ll add to this list
during the next
sessions as weird rare
lesions are presented
I – Case 3
Motion and MRI = NOT GOOD!
T2 images take longer to acquire than T1
Adding fat saturation ↑↑ time of acquisition
I – Case 3
Bone Algorithm Makes Crappy Soft
Tissue!
If lymphoma is a
possibility, send fresh
tissue for flow
cytometry.
Marginal zone lymphoma
is one type of low
grade B-cell
lymphoma.
MALTOMA is most
frequent.
Distinguished from
follicular, mantle cell
and small cell
lymphoma by
morphology and
markers.
Antigen
Status in
MZL
CD20
Positive
CD79a
Positive
CD5
Negative
CD10
Negative
CD23
Negative
CD43
Negative
cyclin D1
Negative
I.4: A Wolf in Bear’s Clothing
I – Case 4
Don’t underestimate CECT!
I – Case 4
Gadolinium good, but over-rated!
Extramedullary Myloid Tumor
and Chloroma are other
terms
Remember Flow Cytometry!
Hematologic Malignancies can
present in “liquid” or solid
forms with identical cell
types: Myeloid Sarcoma vs
AML; SLL vs CLL
Myeloperoxidase expression is
defining; also positive for
CD68
Bone, soft tissue, skin and
lymph nodes are most
frequent sites
I.5: No Rhabdo?
I – Case 5
CT vs MRI
“Feathery” interface with intraconal fat implies
intraconal extension!
I – Case 5
Is the process intra-conal??
“Feathery” interface with intraconal fat implies
intraconal extension!
MRI: T1 C Gd FS
• Fungal organisms
(Zygomycoses, Aspergillus and
Candida species) are readily
identified in with silver stains
• Speciation based on stains is
not generally advised.
• Send cultures
Session I: What have we learned?
1. In the right setting, DWI can change the dx!
Most MRI = anatomic, but DWI = physiology
2. Not every image with black CSF is true T1
Each new sequence has different limitations
3. Stuff vs thing = helps come up with DDx
4. Gd only one tool in the toolbox
5. A good CECT is another great tool
6. “Feathery” interface is intra-conal
Session I: What have we learned?
• If infection is a diagnostic consideration, send
tissue for cultures; special stains are not optimal
for speciation
• If hematologic malignancy is a diagnostic
consideration, send tissue for flow cytometry and
cytogenetics
• Both infiltrative and pilocytic astrocytomas can
involve the optic pathways; pilocytics are much
more frequent
II.1: Behind the Curtain
II – Case 1
What can I say?
Three separate lesions, should have been mets
Sometimes, you need a good pathologist!
Pathologist’s view:
Inflammatory pseudotumor is a non-satisfying diagnosis,
usually one of exclusion
Mixture of chronic inflammatory cells and stromal
response causing a mass (NOT “pseudo-”)
Combines many entities with
variable outcomes
Unknown etiology; rule out
lymphoma
II.2: Deaf and Dizzy. Have We Been Susacked?
II – Case 2
Physiologic Imaging Trumps Anatomy
II – Case 2
Physiologic Imaging Trumps Anatomy
• High grade B-cell lymphoma localized to vascular
lumens
• Presents in the brain and skin most often
• Multiple infarcts with variable distribution
• Lymphoma unable to traverse blood brain barrier?
• Dismal prognosis
Primary CNS Lymphoma
Intravascular Lymphoma
II.3: It’s All In Your Head
II – Case 3
“Stuff” differential got longer….
Histiocytoses Involving the CNS
CD68 S-100
CD1a
Langerhans cell histiocytosis: +
+
+
Rosai-Dorfman disease:
+
+
(sinus histiocytosis with massive emperipolesis
lymphadenopathy)
Histiocytic sarcoma
+
Erdheim-Chester Disease
+
lipid laden histiocytes
with
multinucleated
cells
II.4: Is it Naughty or Nice?
II – Case 4
If it looks like cotton…think MS
Stroke
Most frequent cause of
lawsuit in
neuropathology is the
misdiagnosis of
demyelinating disease
as a malignant
astrocytoma
Demyelinating
Disease
Macrophages are
misinterpreted to be
neoplastic astrocytes
Finding macrophages
in a CNS biopsy should
alert to non-neoplastic
diseases, like MS or
stroke (always atypical
presentations)
CD68
II.5: A Difficult Bug to Swallow
II – Case 5
T1 – Always look at anterior clinoid
Mets or meningioma
II – Case 5
Whole body PET not good for skull base
Many patients present to medical attention with a
metastatic carcinoma to the CNS without
knowledge of a primary neoplasm.
Advances in imaging and immunohistochemical
markers have made the search for a primary
neoplasm much more successful.
TTF1/Napsin
Session II: What have we learned?
• Sometimes lesions don’t follow the “rules”
Why did pseudotumor look like a thing?
• DWI is a great tool
• Erdheim-Chester likes the hypothalamus
• When you see cotton, think MS
• Orbital experts should use T1 images
routinely, and put anterior clinoid process
on your checklist!
Session II: What have we learned?
• Inflammatory pseudotumors are real diseases, but
poorly understood and likely represent multiple
etiologies.
• Intravascular lymphoma has similar malignant Bcells to primary CNS lymphoma, but trapped in blood
vessels.
• Histiocytic infiltrates require subclassification based
on morphology and markers.
• Fulminant cases of demyelinating disease can look
like neoplasms radiologically and pathologically.
Have a Good Lunch
• Be back at 1PM
• We start promptly at 1:10PM