September 2009 Archives

Primary CNS lymphoma

This patient experienced a rapidly progressive decline in mental status.  There was diffuse white matter signal abnormality associated with a focal enhancing lesion in the superior frontal lobe.

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Primary CNS Lymphomas (PCNSL)

  • Rare form of Extranodal non-Hodgkin's Lymphomas
  • Prevalence:  2.2- 2.7% of all primary brain tumors diagnosed in the US.
  • Age: 60-70s, rare in children
  • Sex: male:female= 2:1
  • Locations: Throughout CNS, brain, leptomeninges, spinal cord, or eyes.
  • Risk factors:Congenital or Acquired immunodeficiency, HIV.
  • CNS lymphomas are likely to be diffuse, angiocentric growth pattern, solid sheets can be present with necrosis, hemorrhages are common.

Clinical: 70% had focal neurologic deficits, 43% had neuropsychiatric symptoms,33%had increased intracranial pressure,14%had seizures, and 4%had ocular symptoms.

Imaging: CT shows hyperdense masses at subcortical white matter with contrast-enhancement, peritumoral edema is less severe than malignant gliomas: MRI shows isointense to hypointense on T2-weighted MRI images.

Histology:  Diffuse large B-cell lymphoma (DLBCL) is the most common type (90%): 10% are poorly characterized low-grade lymphomas, Burkitt's lymphomas and T-cell lymphomas

Immunohistochemistry:  Positive for B-cell markers( CD20),CD45 +ve, small benign admixed cells are positive for CD3,BCL-2 +ve,BCL-6 +ve, MUM-1 +ve, GFAP +ve in gliotic areas.

DDX: Differential Diagnoses include Glioblastoma, Metastatic tumor, Infarction, Demyelination, Infections(Abscesses)  


1.  Primary CNS lymphoma. Journal of Clinical Oncology, Vol 24, No 8 (March 10), 2006: pp. 1281-1288

2.  Greenfield's Neuropathology, Sixth Edition.

3.  Primary Central Nervous system Lymphoma. Archives of Pathology and Laboratory Medicine: Vol. 132, No. 11, pp. 1830-1834.


Olfactory Neuroblastoma

This tumor involved the cribriform plate with extension into the brain and adjacent sinuses.

Olfactory Neuroblastoma: ONB

  • Also called"  Esthesioneuroblastoma", Neuroepithelial origin
  • Age: Bimodal, 20-30 years and 60-70 years
  • Sex: Male predilection
  • Incidence: 2-3% of primary tumors that involve nasal epithelium
  • Locations: Roof of the nasal vault, upper third of nasal septum, superior turbinate, superior middle turbinate

Clinical: Slow growing tumors, nasal obstruction, anosmia, epistaxis, rhinorrhea, orbital invlovement or brain involvement

Neuroimaging: Homogeneous mass with uniform vascular enhancement

Histopathology: Neuroepithelial cells arranged in the classic pseudorosette pattern with fibrillar intracellular background, marked microvascularity. The cells are round or fusiform with few cytoplasms. Homer-Wright or Flexner like substances scatter within the tumor.

Immunohistochemistry: Synaptophysin +ve, MAP-2 +ve, Chromogranin A +ve, NSE +ve, CK +ve is less common, CEA -ve, EMA -ve, GFAP -ve, S100 +ve in isolated cells, CD99 +ve

DDX: Differential diagnosis include "Round blue cell tumors", lymphoma,Embryonal rhabdomyosarcoma, PNET/Ewing's sarcoma,Nasopharyngeal carcinoma,Sinonasal undifferentiated carcinoma, malignant melanoma

References: Greenfield's Neuropathology,Sixth Edition

1: Chin Med J 2007 Feb 5;120(3):224-7. Management of intracranial invasive olfactory neuroblastoma.

A meningothelial meningioma that was embolized prior to surgery


Meningothelial Meningioma:

  • WHO Grade I
  • Age: middle-aged, can occur at any age,rare in children
  • Sex: Female predilection
  • Locations:Anywhere in along the neuraxis, intracranial,intraventricular, spinal,extracranial
  • Risk factor: Ionizing radiation, ?Progesterone, NF-2 in young onset
  • Clinical: Headache ,Seizure and Increased ICP, site specific symptoms

Neuroimaging: Unenhanced meningioma shows isodense, well-demarcated,lobulated mass associated with the dura, uniformly enhanced after contrast, edema associates with the breakdown of blood vessel

1: T1-weighted MRI shows isodense or hypodense mass in relation to the grey matter                 (enhances with contrast)

2: T2-weight MRI shows isodense or hyperdense lesion

Histopathology:  Uniform tumor cells forming lobules surrounded by thin collagen septum, nuclei are round or oval,pale with clumped chromatin, intranuclear,pseudoinclusions common, cell membrane is frequently not well-defined resembling a syncytium, nuclear pleomorphism is not a sign of aggressive behaviour.  Mitosis is low or absent.

Immunohistochemistry: EMA +ve, CK +ve,Vimentin +ve, GFAP -ve,S100 variable, MIB-1 labeling index above 5% suggests likelihood of recurrence

DDX: Differential Diagnosis include Schwannoma( EMA-ve,S100+ve, Vimentin +ve),Astrocytoma(+ve GFAP)

Cytogenetics: Monosomy 22

Post Embolization: Changes include necrosis (most common features), ischemic changes, intravascular Ivalon particles, fibrinoid necrosis of the vascular walls, Increased MIB-1 labeling index.

References:Lancet Neurol. 2006 Dec;5(12):1045-54. Histological classification and molecular genetics of meningiomas.

1: Greenfield's Neuropathology,Sixth Edition

2: The American Journal of Surgical Pathology: October 1996 - Volume 20 - Issue 10 - pp 1224-1230 .Histopathology of Post-embolized Meningiomas

An "arachnoidal" cyst in the lumbar spinal cord

Microscopic evaluation showed the anatomy of the cyst wall to be consistent with cysticercosis. Histological characteristics include microvilli, thin tegument, tegument nuclei, and loose connective tissue, no hooklets or scolices were visible.

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Spinal Cysticercosis (SNCC):

  • Cysticercosis is the most common parasitic disease affecting the central nervous system.
  • Caused by " larval stage" of the pig tapeworm Taenia solium
  • Infection caused by contamination of food by T.solium eggs
  • It's the least common site of Neurocysticercosis
  • Human is the" incidental intermediate host"
  • SNCC incidence is known to be 0.7- 5.85%

Low incidence of SNCC is explained by the sieve effect. The majority of cysticerci cannot pass through the subarachnoid space at the cervical level due to its size and the physiological sieve.CSF reflux at the craniovertebral junction, which propels floating cysts back into the intracranial space rather than the spinal canal, is an another possible reason of why SNCC is rare.

Intramedullary intraspinal cysticercal involvement, usually solitary, most probably occurs through arterial blood circulation

The cysticercus can cause direct mass effect, induce regional or distant inflammatory reaction, and medullary degeneration due to meningitis or vascular compression and insufficiency edema, which can damage medullary parenchyma. Inflammatory reaction against the dead parasite is associated with perilesional edema, which can damage medullary parenchyma.

Histopathology: All cysts have similar structure consisting of 3 layers: outer  or cuticular layer, middle cellular layer and inner fibrillary layer.

Treatment: Surgical removal, Anti-cysticercal therapy (Albendazole +Praziquantel), Steroid

References: Greenfield's Neuropathology,Sixth Edition

1: Yonsei Med J. 2009 Aug;50(4):582-584. A Case of Extensive Spinal Cysticercosis Involving the Whole Spinal Canal in a Patient with a History of Cerebral Cysticercosis
2: Arg Neuropsiquiatr 2006 Mar;64(1):149-52. Intramedullary spinal cysticercosis simulating a conus medullaris tumor: case report.

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