Spotters Set 59 – Neuroradiology cases – FREE ACCESS

1. Melanoma — with retinal detachment and subretinal bleed
   • Clinical: 50–70 y; blurred vision, photopsia, scotoma; risk factors light iris, fair skin, UV exposure; etymology from Greek “melas” (black) + “oma” (tumor)
   • Etiology/Pathophys: Neoplastic proliferation of uveal melanocytes; tumor invades through Bruch membrane → exudative RD and subretinal hemorrhage
   • US: Dome- or collar-button–shaped echogenic choroidal mass with low–medium internal reflectivity; associated exudative RD; subretinal bleed appears as echogenic material in subretinal space
   • CT: Hyperdense intraocular mass on noncontrast CT; homogeneous contrast enhancement; RD seen as crescentic elevation of retina
   • MRI: Choroidal mass hyperintense on T1, hypointense on T2 with uniform post-contrast enhancement; subretinal fluid hyperintense on T1; RD appears as linear separation of neurosensory retina
   • Signs: Collar-button sign from Bruch membrane rupture; T-sign (double rim) on B-scan indicating scleral thickening
   • Frameworks: COMS classification: small (<3 mm), medium (3–8 mm), large (>8 mm) thickness; AJCC TNM staging
   • DDx: Choroidal nevus (flat, homogeneous, minimal RD), metastasis (multifocal, variable reflectivity), hemangioma (high reflectivity, intrinsic vascular channels)
   • Tx: Plaque brachytherapy for medium lesions, enucleation for large tumors or those with extensive RD/bleed, transpupillary thermotherapy or local resection for small lesions
2. Asterion defect in Neurofibromatosis 1
   • Clinical: Children/adults with NF1; café-au-lait spots, neurofibromas, Lisch nodules; may present with headache or palpable skull defect
   • Etiology/Pathophys: NF1 gene mutation → dysplasia of membranous skull bones at sutural junctions causing focal bone resorption
   • Radiograph: Lateral skull film shows ovoid lucency at asterion junction of parietal, occipital, temporal bones
   • CT: Well-defined bony defect at asterion with thinning of surrounding tables; may reveal meningiocele or dural ectasia
   • MRI: CSF-intensity outpouching through asterion defect; meningeal sac with no mass effect unless herniated cortex
   • Signs: Asterion defect sign – lucent window at skull sutural meeting due to NF1 dysplasia
   • DDx: Parietal emissary vein foramen (smooth edges, vascular channel on CT), post-surgical burr hole (irregular margins, history)
   • Tx: Observation if asymptomatic; surgical repair with cranioplasty for CSF leak, meningocele, or cosmetic indication
3. Harlequin eye deformity (unicoronal or bicoronal synostosis)
   • Clinical: Neonate–infant; no sex predilection; asymmetric forehead/orbit, apparent superiorly elevated superolateral orbital rim; strabismus/amblyopia risk; associated syndromic craniosynostosis (Apert, Crouzon, Pfeiffer, Saethre‑Chotzen)
   • Etiology/Pathophys: Premature fusion of a unilateral coronal suture → ipsilateral frontal flattening, contralateral bossing, decreased ipsilateral orbital volume with superior orbital roof elevation and shortened AP orbital dimension; nasal root deviates toward fused side
   • Radiograph: AP skull shows harlequin eye sign—tall, squared superior orbital contour with elevated superolateral rim on fused side; sclerosed, fused coronal suture; frontal asymmetry; possible diffuse “copper‑beaten” impressions if raised ICP
   • US: High‑frequency linear probe over sutures shows loss of hypoechoic suture gap, bony bridging/no motion with ballottement, absent Doppler flow along fused segment
   • CT: 3D‑CT gold standard; bony bridging/sclerosis of one coronal suture, asymmetric anterior cranial fossa, elevated ipsilateral orbital roof and lateral wall retrusion, reduced ipsilateral orbital volume, nasal deviation; assess multisuture involvement and secondary signs of raised ICP
   • MRI: Soft‑tissue/orbital and intracranial assessment; evaluates optic pathways and extraocular muscles, venous sinuses, and associated brain anomalies
   • Signs: Harlequin eye sign (superiorly displaced ipsilateral orbital roof); anterior plagiocephaly pattern; copper‑beaten skull may suggest chronically elevated ICP
   • Frameworks: Craniosynostosis patterns—scaphocephaly (sagittal), brachycephaly (bicoronal), trigonocephaly (metopic), anterior plagiocephaly (unicoronal), posterior plagiocephaly (lambdoid); syndromic vs nonsyndromic classification
   • DDx: Deformational plagiocephaly (patent sutures, occipital flattening, no harlequin sign); lambdoid synostosis (posterior plagiocephaly, mastoid bulge); metopic synostosis (triangular forehead, hypotelorism); frontosphenoidal synostosis (coronal patent but similar orbital changes); orbital roof fracture (irregular fracture lines, traumatic soft‑tissue/air)
   • Tx: Early craniofacial referral; endoscopic strip craniectomy + helmet ideally at 2–4 mo; fronto‑orbital advancement ± anterior vault remodeling around 9–12 mo; ophthalmologic management (amblyopia, astigmatism, strabismus); monitor/mitigate ICP; long‑term follow‑up for re‑synostosis and ocular sequelae
4. Giant tuberculoma affecting the cerebellum
   • Clinical: Children more commonly affected than adults; cerebellar location predominant in pediatric cases; presents with focal neurological deficits, seizures, signs of raised intracranial pressure, obstructive hydrocephalus; may lack systemic TB symptoms; headache, ataxia, cranial nerve palsies common with posterior fossa involvement
   • Etiology/Pathophys: Hematogenous spread of Mycobacterium tuberculosis to CNS; forms granulomatous lesions with caseous necrosis, epithelioid cells, and Langhans giant cells; represents least common CNS TB manifestation; can develop paradoxically during anti-TB treatment
   • CT: Ring-shaped enhancement with contrast; peripheral edema; low-density center representing caseous necrosis; mass effect with possible hydrocephalus; calcification may be present in chronic cases
   • MRI: Low T2 signal intensity (pathognomonic feature); ring enhancement with gadolinium; peripheral edema on FLAIR; restricted diffusion in necrotic center; target sign with central low signal, intermediate ring, and peripheral high signal on T2
   • Nuc Med: Variable uptake on FDG-PET; may show rim enhancement pattern
   • Signs: Target sign on MRI T2 sequences; rim enhancement pattern
   • Frameworks: Classification based on size (giant >3 cm), location (infratentorial vs supratentorial), and imaging characteristics (solid vs cystic)
   • DDx: Primary brain tumors (gliomas, metastases), pyogenic abscess, toxoplasmosis, cysticercosis, sarcoidosis; key differentiator is low T2 signal and target sign favoring tuberculoma
   • Tx: Anti-tubercular therapy (isoniazid, rifampin, ethambutol, pyrazinamide) for 12–18 months; surgical excision for giant lesions causing mass effect or failed medical therapy; steroids for cerebral edema; CSF diversion for hydrocephalus
5. Incisive canal (nasopalatine duct) cyst — nasopalatine duct cyst (NPDC)
   • Clinical: 40–60y; M>F (2:1); often asymptomatic; may present with palatal swelling, pain, or discharge; most common non-odontogenic cyst
   • Etiology/Pathophys: Developmental cyst from nasopalatine duct epithelium that fails to regress during fetal development; cystic degeneration of persistent ductal remnants in incisive canal
   • Radiograph: Heart-shaped or round radiolucency between central incisors; midline anterior maxilla only; well-defined corticated margins; may cause root divergence of adjacent teeth
   • CT: Well-defined cystic lesion in incisive canal/nasopalatine foramen; low attenuation contents; thin wall; may extend into nasal cavity; hourglass configuration when large
   • MRI: T1 variable signal (protein content dependent); T2 hyperintense; thin enhancing wall; no solid components
   • DDx: Periapical cyst (associated with non-vital tooth); radicular cyst (tooth-related); median palatine cyst (more posterior); globulomaxillary cyst (lateral to canine)
   • Tx: Surgical enucleation via palatal approach; complete removal of cyst lining; preserve nasopalatine nerve when possible; recurrence rare with complete excision
6. Nasal encephalocele
   • Clinical: Neonates/infants; equal M:F; nasal mass; CSF rhinorrhea; nasal obstruction; recurrent meningitis
   • Etiology/Pathophys: Neural tube defect causing herniation of brain tissue and/or meninges through bony defect in anterior skull base into nasal cavity
   • CT: Bony defect in anterior skull base; soft tissue mass extending from intracranial space into nasal cavity; brain tissue herniation through cribriform plate or frontonasal suture; associated hydrocephalus in 10–15%
   • MRI: T2 hyperintense CSF; brain tissue with gray/white matter signal; stalk connection to intracranial space; meninges surrounding herniated contents; FLAIR suppresses CSF signal; sagittal T1 best shows skull base defect
   • Frameworks: Anatomic classification – nasofrontal (frontonasal suture), nasoethmoidal (cribriform plate), sphenoethmoidal (sphenoid); Suwanwela classification – sincipital (nasofrontal, nasoethmoidal) vs basal (sphenoethmoidal)
   • DDx: Nasal glioma (no CSF connection, solid); dermoid cyst (no brain tissue, may have hair/fat); nasal polyp (inflammatory, no intracranial connection); meningocele (no brain tissue, CSF only)
   • Tx: Surgical repair with craniotomy and nasal approach; watertight dural closure; bone graft reconstruction of skull base defect
7. Meningioma (spinal)
   • Clinical: 40-70y; F>M (4:1); progressive myelopathy; back pain; radicular pain; weakness; sensory deficits; gait ataxia
   • Etiology/Pathophys: Arise from arachnoid cap cells (meningothelial cells) embedded in dura near nerve root sleeve; benign, slow-growing neoplasm
   • MRI: Intradural extramedullary mass; homogeneous enhancement with gadolinium; T1 isointense to hypointense; T2 hyperintense; dural tail sign may be present; cord compression with displacement
   • CT: Calcification in 20-25% of cases; hyperostosis of adjacent vertebral body may occur
   • Signs: CSF cap sign (CSF rim around tumor); dural tail sign (linear dural enhancement extending from tumor base)
   • Frameworks: WHO Grade I (benign), Grade II (atypical), Grade III (malignant/anaplastic); Simpson grading for extent of resection
   • DDx: Schwannoma (more heterogeneous, target sign on T2); neurofibroma (associated with NF1); leptomeningeal metastases (nodular, multiple); ependymoma (intramedullary)
   • Tx: Gross total resection via laminectomy or laminoplasty; Simpson Grade I–II resection goal; radiation therapy for recurrent/atypical lesions
8. Cortical venous thrombosis with hemorrhage
   • Clinical: Any age; F>M (due to OCP, pregnancy); headache most common; seizures, focal deficits
   • Etiology/Pathophys: Thrombosis of cortical veins → venous congestion → venous infarction with cytotoxic/vasogenic edema; hemorrhagic transformation common
   • CT: Cord sign — hyperdense serpiginous vessel on NECT; hemorrhagic venous infarction appears as hyperdense cortical lesions; CTV may show filling defects
   • MRI: T1: Loss of normal flow void; acute thrombus isointense, subacute hyperintense due to methemoglobin; T2: Acute thrombus hypointense, chronic hyperintense; FLAIR: Hyperintense thrombosed vessels; DWI: May show restricted diffusion in acute thrombus
   • SWI: Blooming artifacts and susceptibility effects in thrombosed cortical veins; thrombosed veins appear prominently dark and enlarged
   • Signs: Hyperintense vein sign on FLAIR; blooming artifact on SWI/GRE; absence of normal flow void on T1/T2; cord sign on CT
   • DDx: Normal anatomical variants (hypoplastic sinuses); slow flow (can cause T1 hyperintensity); arachnoid granulations; arterial infarction
   • Tx: Anticoagulation with heparin followed by warfarin; treat underlying cause; manage increased ICP; seizure prophylaxis if indicated
9. Fenestration of the falx with interdigitated gyri
   • Clinical: Variable age (often adult incidental); usually asymptomatic; may have headaches or seizure evaluation; associated with congenital dural anomalies
   • Etiology/Pathophys: Partial agenesis/fenestration of falx cerebri due to incomplete dural folding in embryogenesis, allowing adjacent gyri to interdigitate across midline
   • CT: Focal defect or gap in falx with gray‑matter density crossing midline; bilateral interdigitating gyri within interhemispheric fissure; preserved cortical ribbon and no cleft cavity
   • MRI: T1/T2 confirms absence of dural septum where gyri extend; normal gyral morphology without CSF‑filled cleft; no associated heterotopia or schizencephalic cleft
   • Signs: Interdigitated gyri sign – gyri from each hemisphere protrude through falcine fenestration and interlock; absence of midline dural septum on sagittal views
   • Frameworks: Falx anomalies classification: hypoplasia, fenestration (focal defect), partial agenesis, total agenesis; differentiate from interhemispheric cysts and holoprosencephaly
   • DDx: Total falx agenesis (complete absence, wide interdigitation); schizencephaly (gray‑matter‑lined CSF cleft to ventricle); interhemispheric arachnoid cyst (CSF signal cavity); cranioplasty defect (history, hardware)
   • Tx: None required for isolated fenestration; surgical intervention only if symptomatic or associated pathology
10. Dyke‑Davidoff‑Masson syndrome (DDMS)
    • Clinical: Any age but typically from fetal/early childhood insult; M>F; seizures, contralateral hemiparesis/hemiplegia, facial asymmetry, developmental delay; neuropsychiatric symptoms common
    • Etiology/Pathophys: Brain insult in fetal life or early childhood causing hemicerebral atrophy/hypoplasia; causes include trauma, infection, ischemia, hemorrhage, prolonged febrile seizures, MCA occlusion
    • Radiograph: Ipsilateral calvarial thickening, hyperpneumatization of frontal sinus and mastoid air cells, elevation of petrous ridge
    • CT: Unilateral cerebral hemiatrophy, ipsilateral ventricular enlargement, compensatory calvarial thickening, hyperpneumatization of frontal sinus/ethmoid/mastoid air cells, elevation of petrous ridge, ipsilateral falcine displacement
    • MRI: Cerebral hemiatrophy with volume loss, ipsilateral ventricular dilatation, sulcal prominence, atrophy of basal ganglia/brainstem, crossed cerebellar diaschisis (contralateral cerebellar atrophy), Wallerian degeneration
    • Frameworks: Two types based on timing: infantile/congenital (in utero/perinatal insult) vs acquired (postnatal); absence of sulcation differentiates congenital from acquired
    • DDx: Sturge‑Weber syndrome (pial enhancement, cortical calcifications); Rasmussen encephalitis (no calvarial changes typically); unilateral MCA occlusion (hemiatrophy in MCA territory only)
    • Tx: Anticonvulsants (valproic acid, levetiracetam), physiotherapy, occupational therapy, speech therapy; hemispherectomy for intractable seizures; supportive care for developmental delays

Previous Case Set || Next Case Set

Further reading and references: Osborn’s Brain