Neurocutaneous Tumors (that's not covered already in CNS tumors)

Question 1

What are the 3 types of Neurofibromas? Are they malignant?

Answer 1

Cutaneous neurofibroma, Solitary Neurofibroma and Plexiform Neurofibromas. Only Plexiform neurofibroma has the potential to become malignant.

Question 2

How do cutaneous neurofibromas look microscopically?

Answer 2

Nodules (sometimes with hyperpigmentations), might become pedunculated, presents in dermis and subQ fat. No capsule but well delianated. Made of spindle cells, lots of collagen little myxoid material.

Question 3

How do solitary neurofibromas differ from cutaneous neurofibroma?

Answer 3

It arises sparodically or in association with neurofibromatosis I, and is a neurofibroma of the Peripheral nerves.The micro is the same as the neurocutaneous version.

Question 4

When do Plexiform Neurofibroma I arise?

Answer 4

Usually only in association with neurofibrosis type I, has a potential for malignant transformation. Can arise anywhere along a nerve.

Question 5

How do plexiform neurofibromas compare with schwannomas?

Answer 5

In a schwannoma the tumor can dissociate from the nerve, it cannot do that in a plexiform neurofibroma because fingers of the tumor insert itself within the nerve tissue itself. Thus it has poorly defined margins.

Question 6

How do plexiform neurofibromas present microscopically?

Answer 6

Loose myxoid background, low cellularity, mix of schwann cells (will have elongated nuclei and extensions of pink cytoplasm), fibroblastic cells (larger and multipolar), scattered inflamm cells including mast cells. Areas of collagen bundle, with “shredded carrot” appearance.

Question 7

What’s the buzzword appearance of Plexiform neurofibromas?

Answer 7

“Shredded Carrot” appearance.

Question 8

What is a “Malignant peripheral Nerve Sheath tumor?”

Answer 8

De novo or from plexiform neurofibroma transformation, these are highly malignant and associated with neurofibromatosis type 1.

Question 9

How do Malignant peripheral nerve sheath tumors present?

Answer 9

Poorly defined tumor mass or masses with invasions into the nerve and adjacent soft tissues. Necrosis is common. Wide micro presentations. Mitosis, necrosis, and extreme nuclear anaplasia.

Question 10

What is a “Triton Tumor?”

Answer 10

It is a malignant peripheral nerve sheath tumor + rhabdomyoblastic differentiation = triton tumor.

Question 11

What has a strong association with Malignant Peripheral Nerve Sheath tumor?

Answer 11

Neurofibromatosis type I.

Question 12

What is “Neurofibromatosis Type I?” (Describe the genetics)

Answer 12

Autosomal Dominant disease, involves the NF1 gene on chromosome 17 q11.2 and encodes the protein “Neurofibromin.”

Question 13

What is the role of the protein “Neurofibromin?”

Answer 13

Probably plays a role in regulating signal transduction.

Question 14

What are people with neurofibromatosis type I more at risk for?

Answer 14

Plexiform and solitary neurofibromas with a propensity for the neurofibromas to go malignant transformations more often than the general public. Also these pt’s are more prone to gliomas of optic nerve, Lisch nodules (pigmented nodules in the iris), and “cafe au lait” spots on skin.

Question 15

What is the course of the disease of patients with neurofibromatosis I?

Answer 15

Could be anything from asymptomatic to progressive disease with spinal deformaties, disfiguring lesions and compression of vital organs.

Question 16

What is the genetics behind Neurofibromatosis type II?

Answer 16

AD like type I but less common than type one. Involved with the NF2 gene on chromosome 22q12 (type 1 was chromosome 17). This codes for the protein “Merlin” which shows similarities to some cytoskeletal proteins.

Question 17

What kind of malignancies do patients with neurofibromatosis type II develop?

Answer 17

Most commonly bilateral CN8 nerve schwannomas (Acoustic Neuroma) and multiple meningiomas. Ependymomas of the spinal cord also possible.

Question 18

What is “schwanosis?”

Answer 18

Nodular ingrowth of schwann cells into the spinal cord.

Question 19

What is “meningioangiomatosis?”

Answer 19

Proliferation of meningeal cells and blood vessels that grow into the brain.

Question 20

What is “glial hamartia?”

Answer 20

Microscopic nodular collections of glial cells at weird locations, esp in the superficial and deep layers of the cerebral cortex.

Question 21

What are the 3 non neoplastic lesions associated with Neurofibromatosis type II?

Answer 21

Glial Hamartia, Meningioangiomatosis and Schwanosis.

Question 22

What is the triad of “Tuberous Sclerosis”?

Answer 22

Mental retardation, seizures and Adenoma Sebaceum.

Question 23

What is “Tuberous Sclerosis?”

Answer 23

An AD defect that leads to the development of Hamartomas and benign neoplasms that involve the brain and other tissues.

Question 24

How does Tuberous Sclerosis present and why are they called this?

Answer 24

Comes from the word Tubers which means potatoes, and it presents as wide, flat and firm gyri. Cortical hamartomas of TS are firm areas of the cortex and altogether resembles a potato.

Question 25

What problems does Tuberous Sclerosis cause in the brain?

Answer 25

Due to growth of tuber like structures there can be obstruction leading to hydrocephalus, also seizures, mental retardations, etc.

Question 26

What characteristic lesion develops in the face of Tuberous Sclerosis?

Answer 26

Facial angiofibroma, also called Adenoma Sebaceum, develops across the nose and cheeks, this is basically a rash.

Question 27

What skin lesions besides the face is associated with Tuberous Sclerosis?

Answer 27

Shagreen patches (raised patches of skin with orange-peel, leathery texture) and Ash leaf patches (hypopigmented areas of skin), both present in the lower back

Question 28

How common are kidney problems with patients that have TS? What are the problems?

Answer 28

40-80% have them, usually cause problems in the 2nd-3rd decade of patient’s lives. Presents with angiomyolipomas and custs. Kidney might bleed, and tehre is also possible possible polycistic kidney disease which will lead to high BP and deterioting kidney function.

Question 29

What problems does TS cause in the heart?

Answer 29

Rhabdomyomas, which are benign rare growths in the heart.

Question 30

What eye problems are associated with TS?

Answer 30

Growth in the retinas of the eye called retinal hamartoma or phakoma.

Question 31

What are “Candle Gutterings” found in TS?

Answer 31

Found in the subependymal region where large cells that look like astrocytes cluster up beneath the ventricular surface and form multiple drop like masses that bulge into the ventricular system = Candle gutterings.

Question 32

What tumor is UNIQUE to TS?

Answer 32

SEGA, Subependymal giant cell astrocytoma, a WHO I, but can obstruct CSF flow.