A young adult male presents with progressive limb numbness and gait disturbances. Medical history was unremarkable.
MRI brain was performed and showed no intracranial abnormalities.
The neurologist ordered an MRI scan of the cervical spinal cord.
Showing MRI images:
What do you see?
A long segment T2-hyperintense lesion in the posterior part of the cervical myelum, specifically in the dorsal columns (‘inverted V-sign’). There is no perilesional oedema, mass effect, or enhancement.
What is the differential diagnosis based on the MRI findings?
Subacute Combined Degeneration due to Vitamin B12 deficiency or inactivation
Intrathecal MTX-induced myelopathy
Vitamin E deficiency
Copper deficiency
Tabes dorsalis (neurosyphilis)
HIV vacuolar myelopathy
More information
The laboratory values of Vitamine B12 were normal, as well as Copper and Vitamin E values.
HIV and Syphilis screening were negative.
The patient finally confirmed recreational (ab)use of nitrous oxide.
What is the most likely diagnosis?
Subacute Combined Degeneration due to nitrous oxide-induced Vitamin B12 inactivation.
Subacute Combined Degeneration
SCD is a neurological complication of vitamin B12 deficiency or inactivation. Several drugs can inactivate vitamin B12 such as metformin and nitrous oxide. Abuse of nitrous oxide inactivates vitamin B12 by oxidizing Cobalt-ion. In case of nitrous oxide abuse, vitamin B12 serum levels can appear normal.
Clinical symptoms include loss of vibration and proprioception in hands and feet and sensory gait ataxia. In severe cases, muscle weakness especially in the distal extremities can be seen.
MRI shows bilateral T2 high signal in the dorsal columns (inverted V sign) which explain the sensory deficits (paraesthesia, propriocepsis, and fine touch). In severe or untreated cases, the lateral columns may be involved leading to motor deficits such as limb weakness, spasticity, and paraplegia. The lesions typically involve a long segment in the cervical and higher thoracic spinal cord and show no enhancement or cord expansion.
It is crucial to promptly identify this disease and treat the vitamin B12 deficiency and/or discontinue the inactivating drug to prevent serious complications.
Polymicrogyria
Bilateral cortical thickening with numerous small gyri with signal characteristics similar to normal grey matter.
Dilated bilateral perivascular spaces in the subjacent white matter.
54-year-old woman:
– Known breast cancer
– Arm paresis and soft-tissue lump
What are the salient findings?
Left: NECT, bone algorithm. Aggressive-like bone lesion with permeative pattern and hair on end periosteal reaction
Right: MRI T1 post-Gd. Associated trans-diploic soft-tissue mass with extracranial and intracranial-extraaxial components. Solid, homogeneous and avidly enhancing. Contiguous dural thickening and enhancement.
What is the differential diagnosis?
DIFFERENTIAL DIAGNOSIS FOR TRANS-DIPLOIC SKULL VAULT LESION WITH AGGRESSIVE-LIKE BONE AFFECTATION
– Always consider in older patients
– Multiplicity and known primary
Imaging
Varies depending on tumor type and aggressiveness
– Lytic: Most tumor types
– Permeative: Highly cellular and small-round cell tumors (PNET, small cell lung, lymphoma)
– Sclerotic/mixed: Prostate, breast. Less frequently: Transitional cell, neuroendocrine, PNET
– Hypervascular: Renal cell, melanoma, thyroid, hepatocarcinoma, lung, neuroendocrine
Possible soft-tissue components
LYTIC AGGRESSIVE BONE LESION/S IN PATIENT >40 years old. METASTASES vs MYELOMA
MULTIPLE MYELOMA (MM)/SOLITARY PLASMOCYTOMA
MULTIPLE MYELOMA (MM)/SOLITARY PLASMOCYTOMA
– Affects older patients (median 68-70 years). Very rare under 40 years (<10%)
Imaging
MM 4 patterns of bone involvement
– Diffuse lytic bone infiltration simulating osteopenia
– Multiple focal lytic well-defined lesions
– Solitary plasmacytoma
– Sclerotic bone lesions (exclusively associated with POEMS sd)
Solitary plasmacytoma in the skull: lytic, aggressive trans-diploic, soft tissues, and hypervascular aspect
CLASSIC APPEARANCE OF MM CLASSIC APPEARANCE OF SOLITARY PLASMOCYTOMA OF THE SKULLLYMPHOMA
LYMPHOMA
– 7% of all bone malignancy; 5% of extranodal lymphoma
– All ages; predominates in adults (peak 50-60 years); men/women 1.5:1
– Secondary dissemination >>> primary bone lymphoma
– Imaging characteristics of a hypercellular small round cell tumour
Imaging
– Trans-diploic permeative bone pattern and abundant of tissue components (small round blue cells spread through Haversian canals conditioning a striking relatively little bone destruction in comparison to important soft-tissue lesions)
– Hyperdensity on NECT, T2 hypodensity and striking diffusion restriction on DWI (all signs related to hypercellularity)
– Homogenous enhancement
– No or little necrosis
CHARACTERISTIC IMAGING FINDINGS FOR LYMPHOMAOSTEOSARCOMA
OSTEOSARCOMA
– Most common primary high-grade bone sarcoma
– Bimodal distribution: 10-14 and >40 years old
– Extremely rare in the skull in adults, and much more frequently arising from coexisting Paget’s disease> >previously irradiated bone> or bone infarction
– Clinically, quickly growing painful mass
Imaging
– Destructive, aggressive lesion, with periosteal reaction, soft tissue-mixed lytic-blastic component. May show “fluffy”, “cloud-like” osteoid matrix.
Secondary osteosarcoma arising in a Pagetic skull. See the globally aggressive pattern and the deep hypointensities inside the soft-tissue components probably transducing osteoid matrix (usually easily depicted on CT, non-available in this case)
MENINGIOMA
MENINGIOMA
– Most common brain tumor (36% of all brain tumors)
– Predilection for middle-aged females
– Can produce neurologic symptoms due to compression
– Most do not infiltrate bone, but when they do it, the hyperostosis is very specific, virtually pathognomonic
– Intra-diploic or trans-diploic meningiomas are less frequent
*Even the great specificity of the hyperostosis, bone involvement can be VERY VARIABLE including aggressive-like lysis and periosteal reactions that do not exclude or go against the diagnostic
Ddx: Hemangiopericytoma (Solitary Fibrous Tumor New WHO 2016 classification). Younger, frequently male patients. Osteolysis possible, but NO hyperostosis. NO calcifications. The rest of imaging features identical to meningioma, differentiation is very difficult and challenging
EXAMPLES OF THE MULTIPLE FACES OF MENINGIOMAS AND THEIR BONE INVOLVEMENT. REMEMBER, POLYMORPHISM IS AN IMPORTANT FEATURE OF THIS ENTITY
With all the information mentioned above:
Could meningiomas condition aggress periosteal reaction? Does it go against its diagnosis
Meningiomas are very frequent, specially in middle-aged woman, if all or the vast majority of features favour this diagnosis, a relatively atypical bone affectation (lysis, periosteal reaction instead of the virtually pathognomonic hyperostosis) may not change the diagnostic orientation.
Bonus clues and some advance imaging pearls
Diffusion: Striking restriction in lymphomas Perfusion: Striking high rCBV in meningiomas Spectroscopy: Alanine (and GLX) in meningiomas. Striking high Cho in lymphoma and plasmacytoma. Striking high lipids in metastases
Back to the case:
ARE THE ADVANCED IMAGING TECHNIQUES HELPFUL?
FINAL DIAGNOSIS: MENINGIOMA (WHO GRADE 2)
TAKE HOME MESSAGE REGARDING MENINGIOMA
– Very frequent, specially middle-aged women
– Important to know the classic characteristic features, some of them are very specific; but recognize the great polymorphism/many faces of this entity
– Advanced imaging can be helpful
– Not all the lesions in a neoplastic patient are metastases
See the characteristic ABRUPT SPARING OF THE BASAL GANGLIA WITH THEIR “BORDERS THAT CAN BE DRAWN WITH A FINE-POINT PEN”.
Other tips:
* Temporal (with anterior and medial predominance) and insular> frontal (with basal predominance) and cingular
* Not rare bilateral
* Look for SAH foci near the silvian fissures
An 89-year-old female patient with aplastic anemia. What do you see?
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CT images without contrast media: Subacute isodense right subdural hematoma, revealed with narrowing of right cerebral hemispheric sulci and right lateral ventricle and minimal midline shift (red arrows), acute left subdural hematoma (blue arrow)
A 24-year-old female patient with headache. What do you see?
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Multinodular and vacuolating neuronal tumor (MVNT): Cortical ribbon-juxtacortical T2 hyperintense (a-b) round to oval nodular lesions, not suppressed on FLAIR images (c) and usually no enhancement (d) may show fair enhancement rarely, without diffusion restriction (not shown)
48-year-old male patient, HIV (+); presented to emergency with headache, confusion, N/V.
What do you see?
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T2 hyperintense lesions of left caudate nucleus, left putaminal and right dentate nucleus , with perilesional edema.
Small corticomedullary T2 hyperintense lesions with faint enhancement.
Caudate and putaminal lesions demonstrates faint peripheric contrast enhancement whereas cerebeller lesion has strong peripheric and central nodular enhancement.
Caudate and cerebellar lesion have tiny microhemorrhages on SWI, a clue for diagnosis.
Toxoplasmosis
· Most common opportunistic CNS infection and most common cause of a mass lesion in AIDS
· Basal ganglia, thalamus, corticomedullary junction and cerebellum frequently involved
· Microhemorrhages can be seen on SWI, lesions may have ring or nodular enhancement
· Major ddx is lymphoma:
– Lymphoma is usually solitary whereas solitary lesions are uncommon in toxoplasmosis.
– Microhemorrhages are uncommon in lymphoma
