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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 MRI1

Pathophysiology

  • Malignant cells reach the leptomeninges via:
    • Haematogenous 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

panels-1

  • 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

  • Intrathecal/systemic chemotherapy and radiotherapy to symptomatic sites; prognosis is poor. Whole-neuraxis MRI plus CSF cytology is the diagnostic combination

Differential diagnosis (leptomeningeal enhancement)

Imaging differential Differentiating feature
Infectious (bacterial) meningitis Diffuse smooth pial enhancement with clinical sepsis and active CSF
Tuberculous meningitis Thick basal enhancement with perforator infarcts and hydrocephalus
Neurosarcoidosis Nodular pial and dural enhancement, often basal, with hypothalamic/stalk involvement
Reactive/post-procedural Thin smooth enhancement after lumbar puncture or shunting, without nodules

  1. Grossman et al. Leptomeningeal carcinomatosis. 1999. Cancer treatment reviews - Open in new tab. ↩