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Leptomeningeal Carcinomatosis

Summary

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  • Leptomeningeal carcinomatosis (LC) is the spread of malignant cells to the leptomeninges and subarachnoid space
  • Presents with multifocal neurological symptoms and signs
  • Diagnosis relies on CSF cytology and neuroimaging, particularly contrast-enhanced MRI

Pathophysiology

  • Malignant cells reach the leptomeninges via:
    • Haeatogenous spread
    • Direct extension from brain or spinal cord metastases
    • Perineural or perivascular spread
  • Tumour cells proliferate in the subarachnoid space, leading to:
    • Obstruction of CSF flow
    • Infiltration of cranial and spinal nerve roots
    • Invasion of brain parenchyma

Demographics

  • Occurs in 5-8% of patients with solid tumours
  • Most common primary tumours:
    • Breast cancer (12-35%)
    • Lung cancer (10-26%)
    • Melanoma (5-25%)
  • Incidence increasing due to improved survival of cancer patients and better diagnostic techniques

Diagnosis

  • Clinical presentation:
    • Headache
    • Altered mental status
    • Cranial nerve palsies
    • Radicular pain
    • Cauda equina syndrome
  • CSF analysis:
    • Cytology (gold standard)
    • Elevated protein
    • Decreased glucose
    • Increased opening pressure
  • Neuroimaging (MRI with gadolinium)
  • Meningeal biopsy (rarely required)

Imaging

  • MRI with gadolinium is the imaging modality of choice
  • Findings:
    • Leptomeningeal enhancement
    • Nodular or linear enhancement along the surface of the brain and spinal cord
    • Hydrocephalus
    • Subarachnoid nodules
    • Cranial nerve enhancement
  • CT with contrast:
    • Less sensitive than MRI
    • May show leptomeningeal enhancement or hydrocephalus
  • FDG-PET:
    • Can detect metabolically active leptomeningeal disease
    • Limited sensitivity for small volume disease

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  • A 70-year-old patient with metastatic prostate cancer presented with right arm weakness.
  • MRI showed hazy T2-hyperintensity within the right frontal lobe and evidence of venous congestion on SWI.
  • Sulcal FLAIR hyperintensity and enhancement indicated leptomeningeal carcinomatosis.

Treatment

  • Multidisciplinary approach:
    • Intrathecal chemotherapy
    • Methotrexate
    • Cytarabine
    • Thiotepa
    • Systemic chemotherapy
    • Radiotherapy
    • Whole brain radiotherapy
    • Focal radiotherapy for symptomatic sites
  • Supportive care:
    • CSF flow diversion (ventriculoperitoneal shunt)
    • Pain management
    • Anticonvulsants
  • Prognosis:
    • Poor, with median survival of 4-6 weeks without treatment
    • Treatment can extend survival to 2-6 months

Differential diagnosis

Differential Diagnosis Differentiating Feature
Infectious meningitis Fever, elevated WBC count, positive CSF cultures
Neurosarcoidosis Hilar lymphadenopathy, elevated ACE levels, non-caseating granulomas
Viral meningoencephalitis Acute onset, viral prodrome, CSF PCR positive for viruses
Subarachnoid haemorrhage Sudden onset severe headache, xanthochromia in CSF
Multiple sclerosis Periventricular white matter lesions on MRI, oligoclonal bands in CSF
Neuroborreliosis (Lyme disease) History of tick bite, erythema migrans rash, positive Lyme serology
Tuberculous meningitis Prolonged symptoms, basilar enhancement on MRI, positive TB cultures
Fungal meningitis Immunocompromised state, positive fungal cultures or antigens in CSF
Vasculitis (primary CNS) Multifocal infarcts on MRI, angiographic abnormalities
Guillain-Barré syndrome Ascending paralysis, albuminocytologic dissociation in CSF