Ch. 6 - Cerebrospinal Fluid

Question 1

What is the total CSF volume, and how much is produced each day?

Answer 1

150mL, with 500mL produced per day (cycled approximately 4x)

Question 2

How can CSF be obtained?

Answer 2

Through lumbar puncture (usually L4, rarely at cisterna magna) or through Ommaya reservoir collection.

Question 3

How do bloody taps obscure diagnosis?

Answer 3

They reduce the significance of neutrophils, eosinophils, or leukemic blasts which may be passengers in the blood.

Question 4

Under what conditions will malignant tumors be identifiable on CSF?

Answer 4

If parenchymal, they must disrupt the ependymal lining to communicate with the ventricles.

If metastatic, they must seed the leptomeninges.

Question 5

How are the sensitivity and specificity of CSF cytology?

Answer 5

Low sensitivity, high specificity.

Question 6

What are the normal elements of CSF cytology?

Answer 6

Often sparse to no cells. Maybe some lymphocytes and monocytes.

Question 7

Describe the cytology of ependymal cells.

Answer 7

Round nuclei with moderate cytoplasm, often cohesive.

Question 8

Describe the cytology of brain matter.

Answer 8

Fibrillary texture containing glial cells, neurons, and maybe some capillaries.

Question 9

How can germinal matrix cells be recognized in neonatal CSF?

Answer 9

(mimics high-grade tumors such as medulloblastoma)

Look for associated siderophages.

Question 10

What are the significance of plasma cells in CSF? Eosinophils?

Answer 10

Plasma cells: Associated with syphilis, MS, neurocysticercosis, lyme disease and TB.

Eosinophils: Parasites (especially tapeworm larvae), coccidoides, VP shunts, hematologic malignancies, drug reactions…

Question 11

In which infectious meningitides should you expect to see the offending organism?

Answer 11

Cryptococcus

Question 12

Describe the morphology of cryptococcus.

Answer 12

5-15um round yeast forms with thick mucinous refractile capsule.

Question 13

Describe the cytology of aseptic meningitis.

Answer 13

Increase in lymphocytes (some irregular) and monocytes.

Question 14

What is Mollaret meningitis?

Answer 14

An idiopathic recurring aseptic meningitis thought to be due to HSV, that resolves spontaneously. Characterized by “Mollaret monocytes” with footprint-like clefted nuclei.

Question 15

What is angiostrongyliasis?

Answer 15

“Rat lungworm”, a parasitic infection with frequent CNS involvement by larvae…that is often self-limited?

Question 16

Describe the morphology of Naegleria Fowleri.

Answer 16

Large nucleus, little cytoplasm. Distinctive motility on wet preparations.

Question 17

What cancers have proclivity towards CSF involvement? What is the most common occult site.

Answer 17

Small cell, melanoma; also breast, lymphomas/leukemias.

Lung is the most common occult site.

Question 18

Describe the cytologies of metastatic lung carcinomas.

Answer 18

Adenocarcinoma: Most common; isolated or small clusters of cells with eccentric nuclei and abundant cytoplasm.
SQC: Rare, cohesive, maybe keratinizing.
SCLC: Small molding apoptotic and necrotic.

Question 19

Describe the cytology of IDC and ILC in the CSF.

Answer 19

IDC: Linear rows or rings. Large with round nucleus and prominent nucleolus and scant cytoplasm.

ILC: Medium-sized isolated cells often with signet ring morphology.

Question 20

Describe the cytology of melanoma metastatic to CSF. Can it be primary in the CNS?

Answer 20

Large cells with macronucleolus, sometimes melanin and associated melanophages.

Yes, in melanosis cerebri there are melanocytes in the leptomeninges.

Question 21

How common is CNS involvement in ALL?

Answer 21

5% of cases–the most common CSF-involving disease in children and among hematologic malignancies overall.

Question 22

What lymphomas have a high affinity for the CNS?

Answer 22

DLBCL, LBL, Burkitt

Question 23

Describe the cytology of primary CNS lymphoma.

Answer 23

Often DLBCL-like. Diagnosis is difficult because of obscuring reactive T-cells, so rely on flow.

Question 24

Describe the cytology of medulloblastoma.

Answer 24

Small to medium-sized cells with hyperchromatic nucleus, scant cytoplasm, nuclear molding and sometimes nucleoli. Looks like any other SRBCT…

Question 25

Describe the cytology of astrocytomas.

Answer 25

Look for large pleomorphic cells with coarse chromatin, irregular nuclear outlines, and cytoplasmic extensions.

Question 26

Describe the cytology of ependymoma.

Answer 26

Isolated or small groups of cells with rouund, eccentric nuclei. Hard to distinguish from benign ependymal cells, though there are anaplastic cases.

Question 27

Describe the cytology of oligodendroglioma.

Answer 27

As you’d expect; uniform polygonal cells with round nuclei and pronounced perinuclear cytoplasmic clearing.

Question 28

Describe the cytology of AT/RT.

Answer 28

Rhabdoid cells, binucleation with inclusion-like structure pushing aside the nucleus.

Question 29

Describe the cytology of choroid plexus tumors.

Answer 29

Varies from simple papilloma (large cluster, uniform cuboidal cells with round nuclei) to carcinoma with pronounced atypia.

Question 30

Describe the cytology of germinoma.

Answer 30

Isolated cells with large round nucleus with prominent nucleolus and moderate cytoplasm (same as seminoma).