Hot Seat Flashcards
Erdheim Chester Disease
Radiographic features
Musculoskeletal involvement is most common, with multifocal extraskeletal involvement seen in 30-50% of patients 1,2.
Skeletal involvement
bilateral, symmetric metaphyseal and diaphyseal sclerosis 1,2
increased uptake on Tc-MDP bone scan 7
cortical thickening
Visceral
lung (see: pulmonary manifestations of Erdheim-Chester disease)
can appear similar to Langerhans cell histiocytosis with predominantly cystic disease, septal thickening and preserved lung volume
chest radiographs will often show interstitial oedema pattern (interlobular septal thickening) with cardiomegaly and pleural effusions that do not respond to diuretics
kidneys and retroperitoneum
often involved
usually asymptomatic 1
hairy kidney sign: irregular symmetric infiltration of the bilateral perirenal and posterior pararenal spaces 11
coated aorta sign: periaortic soft tissue 11
inferior vena cava and pelvic ureters are typically spared, which are useful cross-sectional imaging findings for differentiation of retroperitoneal Erdheim-Chester disease from retroperitoneal fibrosis 8
skin
retro-orbital tissue
optic nerve oedema
retrobulbar masses that can cause proptosis and motility impairment 13
retrograde extension along the optic nerve to the hypothalamus may explain the distribution of brain involvement 4
heart, pericardium and aorta 2
Intracranial
Intracranial involvement of the dura, brain and pituitary are rare 3:
meninges
dural accumulations may mimic meningiomas, with enhancing soft tissue masses
T2 signal characteristics are somewhat different, as the accumulations in Erdheim-Chester disease are hypointense 3
brain
most commonly affecting the pons and cerebellum 14
can also affect the hypothalamus 3,14
intraparenchymal masses appear non-specific 10
pituitary infundibulum 14: presenting with diabetes insipidus
Browns Tumour
A brown tumour, also known as osteitis fibrosa cystica and rarely as osteoclastoma,
Hyperparathyroidism
Look for parathyroid adenoma
Lytic bone lesion differential
F: fibrous dysplasia (FD) or fibrous cortical defect (FCD)
E: enchondroma or eosinophilic granuloma (EG)
G: giant cell tumour (GCT) or geode
N: non-ossifying fibroma (NOF)
O: osteoblastoma
M: metastasis(es)/myeloma
A: aneurysmal bone cyst (ABC)
S: simple (unicameral) bone cyst
H: hyperparathyroidism (brown tumour)
I: infection (osteomyelitis) or infarction (bone infarction) or intraosseous lipoma
C: chondroblastoma or chondromyxoid fibroma
Sarcoidosis
pulmonary and mediastinal manifestations
cardiac manifestations
musculoskeletal manifestations
head and neck manifestations
central nervous system manifestations
abdominal manifestations
cutaneous manifestations
Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH)
an extremely rare but underdiagnosed pulmonary disorder at the benign end of the neuroendocrine cell proliferation spectrum of preinvasive lesions of the lungs.
CT
Characteristic findings suggest the diagnosis, which is usually clinically occult 13:
multiple small solid nodules in a peribronchovascular distribution, more numerous peripherally and with a lower zone predominance
mosaic attenuation due to a combination of air trapping and regional oligaemia as a result of constrictive bronchiolitis
nodular bronchial wall thickening (cell clusters), mucus plugging, and bronchiectasis are common
MIP slabs aid in small nodule detection. MinIPs and expiratory CT highlight air-trapping.
Neurofibromatosis 1
As is the case with many phakomatoses, NF1 results in a variety of abnormalities of variable severity. To make the clinical diagnosis two or more of the following are required 2:
≥2 neurofibromas or ≥1 plexiform neurofibroma
optic nerve glioma
distinctive osseous lesion (such as sphenoid wing dysplasia or thinning of long bone cortex with or without pseudoarthrosis)
>6 café au lait spots evident during one year (prepubertal >0.5 cm, postpubertal >1.5 cm in size)
axillary or inguinal freckling
≥2 iris hamartomas (Lisch nodules)
a primary relative with NF1
phaeochromocytoma
malignant peripheral nerve sheath tumour (MPNST) (~10% of patients) 7
Wilms tumour
rhabdomyosarcoma
renal angiomyolipoma
glioma
juvenile pilocytic astrocytoma (~20% of patients) 13
optic nerve glioma
diffuse brainstem glioma
spinal astrocytoma and spinal pilocytic astrocytoma 9
carcinoid tumour(s)
leiomyoma(s)
leiomyosarcoma
ganglioglioma
leukaemia
high grade astrocytoma with piloid features
NF1 cancers
phaeochromocytoma
malignant peripheral nerve sheath tumour (MPNST) (~10% of patients) 7
Wilms tumour
rhabdomyosarcoma
renal angiomyolipoma
glioma
juvenile pilocytic astrocytoma (~20% of patients) 13
optic nerve glioma
diffuse brainstem glioma
spinal astrocytoma and spinal pilocytic astrocytoma 9
carcinoid tumour(s)
leiomyoma(s)
leiomyosarcoma
ganglioglioma
leukaemia
high grade astrocytoma with piloid features
NF1 CNS findings
FASI (focal areas of signal intensity): occur in deep white matter and basal ganglia or corpus callosum 5, areas of T2/FLAIR hyperintensity with no contrast enhancement
optic nerve glioma or optic pathway glioma (may manifest as enlarged optic foramen)
progressive sphenoid wing dysplasia
J-shaped sella
lambdoid suture defects
dural calcification at the vertex
moyamoya phenomenon (rare)
buphthalmos
Skeletal NF1
Skeletal
Manifestations include:
kyphoscoliosis
posterior vertebral scalloping
hypoplastic posterior elements
enlarged neural foramina
ribbon rib deformity, rib notching, and dysplasia
dural ectasia
tibial pseudoarthrosis or, less commonly, ulnar pseudoarthrosis
bony dysplasias: especially affecting the tibia
severe bowing, gracile bones 11
multiple non-ossifying fibromas
limb hemihypertrophy
Thoracic NF1
mediastinal masses
neurofibroma
lateral thoracic meningocele: typically on the convex side of scoliosis (through widened neural foramina)
extra-adrenal phaeochromocytoma (paraganglioma)
lung parenchymal disease: ~20%
diffuse interstitial fibrosis: lower zone
bullae formation: upper zone
secondary pulmonary arterial hypertension and cor pulmonale
Thoracic NF1
mediastinal masses
neurofibroma
lateral thoracic meningocele: typically on the convex side of scoliosis (through widened neural foramina)
extra-adrenal phaeochromocytoma (paraganglioma)
lung parenchymal disease: ~20%
diffuse interstitial fibrosis: lower zone
bullae formation: upper zone
secondary pulmonary arterial hypertension and cor pulmonale
Vascular and cutaneous NF1
aneurysms and arteriovenous malformations
renal artery stenosis
coarctation of aorta
cutaneous and subcutaneous neurofibromas: benign peripheral nerve sheath tumours
presented as small soft tissue skin nodules on radiological images
Cystic advential disease
Cystic adventitial disease is an uncommon vascular pathology predominantly affecting peripheral vessels. The vast majority of cases occur in arteries, with venous involvement being an extremely rare occurrence 8.
Surgical bypass situation
Epidemiology
It typically affects young to middle-aged individuals without evidence of atherosclerosis or other systemic vascular diseases. There is a recognised male predilection with a M:F ratio of ~15:1 9.
Clinical presentation
Although cystic adventitial disease can affect any peripheral vessel, there is a striking predilection in the popliteal region, affected in ~85% of cases 1,3,4.
Typical symptoms include:
rapidly progressive calf claudication 1,3
lower extremity pain
Pathology
The condition is characterised by a collection of mucinous material (mucous cysts) within the adventitial portion of the wall of the affected vessel.
MRI
Appearances on MRI are variable, depending on the distribution and size of the cysts.
It may be seen as aggregates of multiple small round/ovoid masses originating in the affected arterial wall, which if concentric lead to hourglass stenosis. When the lesions are large, they can have a multiloculated appearance and can displace the artery to one side, the so-called “scimitar sign” 4.
Lesional signal characteristics include:
T1: individual lesions are of variable signal dependent on mucoid content 4
T2/STIR: individual lesions are high signal 1,4
Myeloid sarcoma
Myeloid sarcoma
• Myeloid sarcoma (MS), or granulocytic sarcoma, is a tumoral lesion consists of immature myeloid cells, mainly myeloblasts of granulocytic series- represent focal accumulation of leukaemic cells.
• Also known as chloroma due to its green color attributed to the enzyme myeloperoxidase (MPO).
• A/w AML.
• Less commonly A/w myelodysplastic syndrome, chronic myeloid leukeria and other myeloproliferative disease
Spinal masses
-
spinal ependymoma
spinal astrocytoma (diffuse)
spinal pilocytic astrocytoma
spinal haemangioblastoma
spinal cord metastasis (intramedullary)
Intradural extramedullary
- spinal meningioma
spinal nerve sheath tumours
spinal schwannoma
- spinal neurofibroma
- spinal leptomeningeal metastases
extradural
epidural metastasis
herniated nucleus pulposus
-
epidural haematoma
-
epidural arteriovenous malformation
epidural angiolipoma
- epidural lipomatosis
cauda equina and filum terminale
- myxopapillary ependymoma
spinal nerve sheath tumours
spinal schwannoma
spinal neurofibroma
Transient global ischemia
Hippocampus tiny foci of diffusion restriction
Post contrast FLAIR
Can be t1 or t2
Méningeal enhancement
Breast mets enhancement
Sub Types of multiple sclerosis
Multiple Sclerosis (MS) is a chronic, immune-mediated disease affecting the central nervous system (CNS). It has several clinical subtypes and presents with distinct syndromes at onset.
Subtypes of MS
1. Clinically Isolated Syndrome (CIS)
• A single episode of neurological symptoms caused by demyelination.
• Can progress to MS if MRI shows additional lesions (dissemination in space).
2. Relapsing-Remitting MS (RRMS)
• Most common form (~85% of cases at onset).
• Characterized by acute relapses (exacerbations) followed by periods of remission.
• Incomplete recovery over time can lead to accumulated disability.
3. Secondary Progressive MS (SPMS)
• Follows RRMS after years to decades.
• Gradual worsening of neurological function with or without relapses.
4. Primary Progressive MS (PPMS)
• Affects ~10-15% of MS patients.
• Steady disease progression from onset without clear relapses.
• More common in older onset patients (>40 years) and affects men and women equally.
5. Progressive-Relapsing MS (PRMS) [Now merged with PPMS under newer criteria]
• Progressive disease from onset with occasional relapses.
• Rare subtype under earlier classifications.
Clinical Syndromes at Onset
- Optic Neuritis
• Symptoms: Painful monocular vision loss, reduced color vision (red desaturation), afferent pupillary defect.
• MRI: Often shows demyelinating lesions in the optic nerve. - Brainstem & Cerebellar Syndromes
• Internuclear Ophthalmoplegia (INO): Affected eye cannot adduct, with nystagmus in the abducting eye.
• Ataxia, dysarthria, nystagmus: Indicate cerebellar involvement.
• Facial numbness/weakness: Trigeminal nerve involvement. - Transverse Myelitis
• Partial myelitis (as opposed to complete in NMOSD).
• Symptoms: Weakness, sensory loss, bladder/bowel dysfunction.
• MRI: Lesions in the spinal cord (commonly cervical or thoracic). - Lhermitte’s Sign
• Electrical shock-like sensation radiating down the spine with neck flexion.
• Suggests cervical spinal cord involvement. - Uhthoff’s Phenomenon
• Worsening of symptoms with heat or exercise.
• Due to conduction block in demyelinated nerves. - Cognitive and Fatigue Syndromes
• Cognitive impairment (memory, processing speed, attention deficits).
• Profound fatigue, often out of proportion to physical symptoms.
Would you like a breakdown of imaging findings or differential diagnoses?
MS syndromes
It seems like you might be referring to Marburg’s Variant of Multiple Sclerosis (Marburg’s Disease) rather than “Marborgs syndrome.”
Marburg’s Variant of MS (Malignant MS)
• A rare and aggressive form of MS that progresses rapidly.
• Often considered a fulminant, monophasic variant of relapsing-remitting MS (RRMS) but with devastating outcomes.
• Can lead to severe disability or death within months to a few years if untreated.
Clinical Features
• Rapid onset of severe neurological deficits (e.g., hemiparesis, ataxia, seizures, brainstem dysfunction).
• Symptoms progress much faster than in typical MS.
• Severe cognitive impairment and encephalopathy can occur.
• High frequency of optic neuritis and transverse myelitis.
Radiologic Findings
• Large tumefactive lesions with mass effect, edema, and ring enhancement.
• Multiple areas of demyelination, often confluent.
• Can mimic brain tumors, neuromyelitis optica (NMO), or ADEM (acute disseminated encephalomyelitis).
Pathology
• Extensive macrophage infiltration and myelin destruction.
• Unlike classical MS, inflammatory infiltrates are more aggressive.
• Necrosis may be present in severe cases.
Treatment
• High-dose corticosteroids (IV methylprednisolone).
• Plasma exchange (PLEX) for steroid-refractory cases.
• Aggressive immunosuppression (e.g., rituximab, alemtuzumab, natalizumab).
• HSCT (hematopoietic stem cell transplantation) has been considered in severe cases.
Prognosis
• Poor without aggressive treatment.
• Significant risk of early disability or mortality.
• Some patients transition into progressive MS, while others experience a monophasic catastrophic course.
Would you like a differential for aggressive demyelinating diseases or imaging comparisons with tumef
Other syndromes
In addition to Marburg’s Variant (Malignant MS), there are several other rare and aggressive variants of multiple sclerosis (MS) that differ from the typical relapsing-remitting or progressive forms. These include:
- Tumefactive Multiple Sclerosis
• Features:
• Large (>2 cm), mass-like demyelinating lesions with edema and ring enhancement.
• May mimic brain tumors (e.g., glioblastoma) or abscesses.
• Often presents with severe headaches, cognitive dysfunction, aphasia, or seizures (which are rare in typical MS).
• Diagnosis:
• MRI: Lesions with open-ring enhancement (distinct from tumors).
• Often solitary or few lesions rather than the typical multiple white matter plaques.
• CSF: Oligoclonal bands (OCBs) may be present.
• Treatment:
• High-dose IV steroids, plasmapheresis, or immunosuppressants if severe.
• Some cases remain monophasic, but others evolve into classical MS. - Balo’s Concentric Sclerosis
• Features:
• Rare, rapidly progressive MS variant.
• Characteristic alternating rings of demyelination and preserved myelin (resembles tree rings).
• Often presents with acute neurological deterioration, seizures, hemiparesis, or cognitive decline.
• Diagnosis:
• MRI: Concentric ring-like lesions (highly specific for Balo’s disease).
• CSF: May have OCBs, but not always.
• Treatment:
• High-dose steroids, PLEX, IV immunoglobulin (IVIG).
• Can be monophasic or progress to classical MS. - Schilder’s Disease (Diffuse Myelinoclastic MS)
• Features:
• Childhood-onset variant, typically between 7-14 years old.
• Rapid cognitive decline, ataxia, and behavioral changes.
• Often confused with leukodystrophies or brain tumors.
• Diagnosis:
• MRI: Bilateral, large (>3 cm) symmetrical white matter lesions in the cerebral hemispheres.
• CSF: May show inflammatory markers but less commonly has OCBs.
• Treatment:
• High-dose steroids, immunosuppressants, and biologic therapies.
• Can progress to severe disability or a progressive MS phenotype. - Neuromyelitis Optica Spectrum Disorder (NMOSD) – MS Mimic
• Not true MS but often misdiagnosed as such.
• Key Differences from MS:
• Longitudinally extensive transverse myelitis (LETM) (>3 vertebral segments).
• Severe optic neuritis, often bilateral.
• AQP4-IgG positive (Aquaporin-4 antibody) (helps differentiate from MS).
• Attacks are more severe and cause permanent disability if untreated.
• Treatment:
• Does not respond well to MS drugs like interferons.
• Requires rituximab, satralizumab, or eculizumab. - Acute Disseminated Encephalomyelitis (ADEM) – Monophasic MS-like Syndrome
• Features:
• Often follows a viral infection or vaccination.
• More common in children and young adults.
• Presents with encephalopathy (confusion, coma), fever, ataxia, and widespread neurological deficits.
• Diagnosis:
• MRI: Large, asymmetric white matter lesions, often with deep gray matter involvement.
• CSF: Mild pleocytosis, often no oligoclonal bands (unlike MS).
• Treatment:
• High-dose steroids, IVIG, or plasmapheresis if severe.
• Often monophasic, but a subset of patients later develop MS.
Comparison Table of Aggressive MS Variants
Variant Key Features MRI Findings Prognosis
Marburg’s MS Fulminant, rapid disability Large tumefactive lesions, mass effect High mortality without early treatment
Tumefactive MS Mass-like lesion, mimics glioma >2 cm lesion, open-ring enhancement Can be monophasic or convert to MS
Balo’s Disease Concentric demyelination, acute onset Alternating rings on MRI Can be self-limiting or progressive
Schilder’s Disease Childhood onset, cognitive decline Large, bilateral white matter lesions Severe, often progressive
NMOSD (MS mimic) LETM, bilateral optic neuritis Long spinal cord lesions, AQP4-IgG+ Relapsing but different from MS
ADEM Post-infect
Rhombencephalitis
Rhombencephalitis (Brainstem Encephalitis)
Rhombencephalitis refers to inflammation of the brainstem (pons, medulla, midbrain, and sometimes cerebellum), typically due to infectious, autoimmune, or paraneoplastic causes. It can be life-threatening due to involvement of vital structures controlling respiration, consciousness, and cranial nerves.
Causes of Rhombencephalitis
- Infectious Causes
• Bacterial:
• Listeria monocytogenes (most common cause in immunocompetent adults)
• Mycobacterium tuberculosis
• Brucella spp.
• Borrelia burgdorferi (Neuroborreliosis, Lyme disease)
• Treponema pallidum (Neurosyphilis)
• Viral:
• Herpes simplex virus (HSV-1, HSV-2) (severe cases with hemorrhagic necrosis)
• Enteroviruses (Coxsackievirus, Poliovirus)
• Rabies virus (brainstem involvement in later stages)
• Varicella-zoster virus (VZV)
• Japanese encephalitis virus, West Nile virus
• Fungal & Parasitic:
• Cryptococcus neoformans (especially in HIV/AIDS)
• Toxoplasma gondii (in immunocompromised patients) - Autoimmune & Paraneoplastic Causes
• Multiple Sclerosis (MS)
• Bickerstaff’s Brainstem Encephalitis (BBE) (autoimmune GQ1b antibodies, overlaps with Miller Fisher syndrome)
• Neurosarcoidosis
• Anti-Ma2 Paraneoplastic Encephalitis (associated with testicular or lung cancer)
• Behçet’s Disease
• Autoimmune GFAP Astrocytopathy - Other Inflammatory Causes
• Acute Disseminated Encephalomyelitis (ADEM)
• Neuro-Behçet’s disease
• Lupus cerebritis (SLE-associated brainstem involvement)
Clinical Features of Rhombencephalitis
• Fever, headache, nausea/vomiting
• Cranial nerve palsies (especially CN VI-VIII → diplopia, facial weakness, dysphagia, vertigo)
• Ataxia, dysarthria (cerebellar involvement)
• Ophthalmoplegia (seen in BBE and Miller Fisher syndrome)
• Altered mental status, coma (severe cases)
• Respiratory failure (medullary involvement)
Radiologic Features
• MRI Brain (preferred imaging modality)
• T2/FLAIR hyperintensity in brainstem (pons, medulla, midbrain)
• Contrast enhancement (seen in infectious, inflammatory, or paraneoplastic cases)
• Restricted diffusion (seen in viral encephalitis)
• Ring-enhancing lesions in Listeria, TB, or parasitic infections
• CSF Findings
• Lymphocytic pleocytosis (viral, autoimmune)
• Neutrophilic predominance (bacterial, Listeria)
• Elevated protein, normal or low glucose (infectious causes)
• Oligoclonal bands (if MS-related)
Management
1. Empirical Antibiotics (if bacterial suspected)
• Ampicillin + Gentamicin (for Listeria in immunocompromised)
• Ceftriaxone + Vancomycin (for bacterial meningitis causes)
• Doxycycline (if rickettsial or Lyme suspected)
2. Antiviral Therapy
• IV Acyclovir (for HSV, VZV)
• Ribavirin (for some viral encephalitides)
3. Immunosuppression (if autoimmune suspected)
• High-dose steroids
• IVIG or plasmapheresis (if Bickerstaff’s or paraneoplastic)
4. Supportive Care
• ICU monitoring if brainstem dysfunction leads to respiratory failure.
• Mechanical ventilation if needed.
• Physical therapy for long-term recovery.
Prognosis
• Bacterial and viral causes: Prognosis depends on early treatment; Listeria has high mortality if untreated.
• Autoimmune causes: Can have relapsing-remitting course (e.g., Bickerstaff’s encephalitis, MS).
• Paraneoplastic causes: Poor prognosis unless underlying malignancy is treated.
Key Takeaways
• Listeria monocytogenes is the most common bacterial cause.
• MRI is crucial for diagnosis, showing brainstem hyperintensities.
• Cranial nerve involvement + fever + brainstem symptoms → suspect rhombencephalitis.
• Early antibiotics, antivirals, or immunosuppressive therapy are key to preventing severe disability.
Would you like MRI examples or a case-based discussion on specific causes?
Temporal lobe signal
HSV
Acute cerebral ischemia
Status epileptic is
Limbic encephalitis
Infiltrating glioma
Ring enhancing lesions
Intracranial abscess
Neurosurgical opinion
Vasogenic oedema
Miliary nodular pattern in upper zones differential
A miliary nodular pattern refers to numerous, tiny (1–4 mm) nodules scattered throughout the lungs, and when predominantly in the upper zones, the differential narrows somewhat. Here’s a focused differential for upper-zone predominant miliary nodules:
Top Differentials (Upper Zone Predominance):
1. Miliary Tuberculosis
• Classic cause of miliary pattern, often upper-lobe dominant due to oxygen tension
• May have constitutional symptoms (fever, weight loss, night sweats)
• Look for lymphadenopathy, hepatosplenomegaly, bone marrow involvement
2. Pneumoconioses (esp. Silicosis, Coal Workers’ Pneumoconiosis)
• Inhalational exposure history (mining, sandblasting, quarrying)
• Upper lobe-predominant micronodules, often with egg-shell calcified nodes
3. Sarcoidosis (early micronodular stage)
• Non-caseating granulomas; can appear miliary in early stages
• Often upper/mid-zone, perilymphatic distribution may evolve
• Look for mediastinal/hilar lymphadenopathy
Other Differentials (less common, but possible):
4. Metastatic Disease (e.g., thyroid, renal, melanoma, choriocarcinoma)
• Hematogenous spread may present with miliary pattern
• Often random distribution, but upper zones can be favored in some cases
5. Fungal Infections
• Histoplasmosis, especially in endemic areas
• May mimic miliary TB; consider immunosuppression, exposure history
6. Langerhans Cell Histiocytosis (PLCH)
• Young adult smokers
• Upper/mid-zone nodules and cysts; can start as nodules before cavitation
• Spares costophrenic angles
