In last month’s blog, we talked about infection prevention. One of the strategies was to use more acidic soaps & lotions. This month, let’s investigate the composition of your skin & why those products are better for preventing infection.

Skin is composed of two main layers: the epidermis and the dermis. The outside layer (epidermis) doesn’t have blood vessels but the next layer does.  (If a skin injury or wound causes bleeding, you know its depth is at least to the dermis.)  The outer layer (sometimes called the acid mantle or hydrolipid film) has special qualities that prevent water loss & make it a good barrier to infection.  One quality is being composed of lipids which reduces water loss and keeps your skin flexible.  As the name “acid mantle” suggests, another quality is having a lower pH (or being more acidic than neutral).  That’s a good trait because we carry around harmful bacteria all the time (including bacteria that cause common infection(s) in lymphedema: Staphylococcus & Streptococcus). The acidity comes from sebum lipids (of your sebaceous glands – or oil glands) & sweat that excrete a wax-like substance to a hair follicle. ^{1, 2, 4}

Because of the acidic-lipid properties, you need to use products that are similar to your skin – both in pH level & with characteristics that aid in reducing water evaporation. Because immunity is compromised in tissue with lymphedema, you need to take good care of your skin as it is the first line of defense. We’ll discuss product ingredients, causes of compromised skin & product recommendations in the upcoming course & ebook on lymphedema management. For now, ideal products should have a pH between 5-7, contain barrier-forming lipids (like ceramides) & possess moisturizing characteristics (such as urea). You can find additional information here.

Most soaps & lotions are more alkaline (pH of 10-11)¹ which can change the pH level & bacterial resistance of your skin. Alkaline products also reduce the thickness of your skin and break down the lipid coating.²

Besides soaps & lotions, other factors impact skin integrity. Some of these factors include: sun, hydration, nutrition, smoking, obesity, medications & age. So use sunscreen, drink water, eat healthy, don’t smoke, lose weight, be healthy — & stay young (let me know if you figure that one out!).

In February, we’ll answer the question: Why People with Lymphedema are Prone to Infection.

References
¹ Foldi, M, Foldi, E. (2006). Foldi’s Textbook of Lymphology (2^nd ed.), p. 623-627. Germany: Urban and Fisher.
² Bryant, R. Nix, D. (2016) Acute & Chronic Wounds (5^th edition), p 40-41, 46-59. Elsevier Inc.
³ attribution: <a href=”http://www.freepik.com”>Designed by macrovector / Freepik</a>
⁴ https://www.britannica.com/science/lipid
⁵ attribution: <a href=”http://www.freepik.com”>Designed by brgfx / Freepik</a>

(How Your Lymphatic System Defends Your Body and Keeps You Safe)

Several years ago I came across my grandfather’s old Navy manual.  He enlisted in the Navy underage, determined to join, near the time of Pearl Harbor.  The attack against Pearl Harbor forced the United States into World War II.  His subsequent years saw a lot of action – events he would never talk about.  Only in reading his journal entries years later (in the front and back pages of his handbook) did I gain greater insight into what he experienced. He wrote of being attacked by bombers and torpedo planes in the early morning hours. “[A]bout two o’clock they dived at us just missed us with a torpedo.” He continued, “May our luck hold out and God watch over us in time of battle which is very often.”  I knew he had a fear of water but only understood why later: He had been knocked into the ocean during an enemy attack against his destroyer warship.  Ultimately, he was honorably discharged after developing post-traumatic stress disorder (PTSD).

Many times we go about our daily lives not giving thought to the sacrifices those in our military make (in order that we might remain free and live each day as we do). Their sacrifices include missing the comfort of home; separation from loved ones; missing birthdays, anniversaries and holidays; missing a child’s milestones; potentially sustaining lifelong mental, emotional and physical trauma; and, some even sacrifice their very life on our behalf.  May President Reagan’s words ring true this month (and every month), “We will always remember. We will always be proud. We will always be prepared so we may be always free.” ⁸

To all who have served (and presently serve) in our armed forces: Thank you.

In honor of Veterans Day, how does your lymphatic system play a role in defending your body and keeping you safe?

Men and women in the Air Force, Army, Navy, Marine Corps, Coast Guard, and recent Space Force as well as the National Guard preserve our freedom by securing our country, protecting our interests, preventing potential attacks and fighting on our behalf when we do go to war. We even have elite special operations forces (highly trained and skilled individuals with specialized knowledge). To best perform these functions, the military must be strong, healthy and able to respond swiftly. In his 1793 State of the Union Address, President George Washington said, “[I]f we desire to secure peace …it must be known that we are at all times ready for war.” ¹ The best way to prevent an opportunist from gaining a foothold is to always be strong, prepared, and willing to act, if necessary.

Your body’s defense system is similarly made up of various branches creating its own armed forces:  Your skin, stomach (acid) and digestive system, tears, mucus, cilia (hair-like projections), saliva and lymphatic system make up your “armed forces.”  The lymphatic system has structural components made of vessels and organs. These include:

• lymph vessels – lymph capillaries, precollectors, collectors (lymphangions) and trunks
• primary lymph organs – red bone marrow (housing stem cells that become lymphocytes) and the thymus gland
• secondary lymph organs – spleen, lymph nodes (such as tonsils) and mucosa-associated lymphatic tissue (membranes that line the GI tract like Peyer’s patches, respiratory airways, urinary tract and reproductive tract). ^3,4

Your body fends off attacks from an enemy such as a pathogen or microbe (like a virus or bacteria) by neutralizing it, repairing damage (from bumps, cuts, burns, chemicals, etc.) and eliminating abnormal or degenerative cells (like cancer).  The body provides two types of defense:

Nonspecific³ – A general protection against invasion by pathogens through physical barriers (skin and mucus membranes), production of antimicrobial chemicals to inhibit microbe growth, natural killer cells (a.k.a. white blood cells or lymphocytes), phagocytosis (ingesting a pathogen), fever and inflammation.

Examples: Thick mucus and cilia filter air and trap microbes, dust and pollutants. Tears bathe the eye surface, washing away microbes as you blink. Cells that get infected with a virus produce messages (proteins called interferons) that signal other cells of the invasion. Many lymphatic cells (macrophages, B and T lymphocytes) produce these proteins. Non-infected cells get the message and ready themselves for attack (i.e. they make proteins to inhibit their own invasion of a virus which replicates itself using the cell). The blood contains a group of soldiers (i.e. inactive proteins) that activate themselves to bolster defenses (by enhancing immune, allergic and inflammatory reactions). Some soldiers even combine forces to punch holes in the plasma membrane of a microbe (cytolysis) causing it to rupture. How awesome is that?

If physical barriers and antimicrobial chemicals don’t work, the next lines of defense are natural killer cells and phagocytes (WBCs or lymphocytes) which destroy intruders. Killer cells patrol the body, interacting with other cells (checking “ID cards”). If a cell doesn’t match up (like a cancer cell)? It’s “Hasta la vista, Baby.” ⁶  Some phagocytes also patrol the body while others remain stationed at a post (in tissue). They ingest (imprison) an invader, unleash chemicals to kill the microbe and digest the remains. What a rough way to go! Anything that can’t be degraded is contained in residual bodies (mini-prisons) which are expelled into the interstitial space and cleaned up by the lymph capillaries.

Finally, there is inflammation and fever.  If invaders have caused tissue damage, the body responds with an inflammatory response (a loud siren) resulting in widening of roads (enlarging blood vessels, a process called vasodilation) and more eagerly opening gates (increasing blood vessel permeability), to allow soldiers, clean up personnel and paramedics (antibodies, phagocytes and clot-forming chemicals in blood) to enter the trauma zone.

Specific³ – A specific, adapted defense response (immunity) to a particular pathogen (called an antigen) is launched by the lymphatic system (T and B lymphocytes) and is the most potent.⁵ This takes some smarts!  It is sort of like profiling (antigens are external molecular structures or characteristics that identify the pathogen).  The lymphatic system not only recognizes the invader but remembers it next time around and responds even faster. These are your “elite special operations forces.”  T and B cells develop in red bone marrow. B cells remain there while T cells migrate to the thymus to complete their training (development). Before either cell leaves their training base, it becomes highly trained and skilled with specialized knowledge (in the form of distinctive surface proteins) in order to recognize specific enemies. In fact, “[b]efore a particular antigen ever enters the body, T and B lymphocytes that can recognize and respond to that intruder are ready and waiting.”⁷ That kind of preparedness would make President George Washington proud!

When an antigen is recognized, B and T cells respond in two ways: cellular or humoral. In cellular, some T cells become killer cells and directly attack. This is sort of like a reconnaissance mission during which T cells scout the body for enemies and once identified, attack.  In humoral, B cells become plasma cells which make and secrete proteins (antibodies or immunoglobulins).  These bind to and inactivate a particular antigen. This is sort of like a reconnaissance mission during which B cells disable and neutralize the enemy.

How can your lymphatic system “always be strong, prepared, and willing to act?” By you following a healthy regimen:  Get plenty of rest. Eat healthy. Reduce stress. Practice good hygiene and wash your hands often. Exercise. Maintain a healthy weight. Don’t do unhealthy things (drinking too much, smoking, etc.). And, given that lymphatics slow down as we age (restricting the transport of antibodies), ² consider getting a manual lymph drainage massage from time to time.

¹https://avalon.law.yale.edu/18th_century/washs05.asp
²Verlag, K. (1998). Compendium of Dr. Vodder’s Manual Lymph Drainage, p. 22-23. Germany: Huthig GmbH.
³Tortora, G., Grabowski, S. (1996). Principles of Anatomy and Physiology (8^th ed.), p. 671-706. New York: HarperCollins College Publishers.
⁴Foldi, M, Foldi, E. (2006). Foldi’s Textbook of Lymphology (2^nd ed.), p. 2-8. Germany: Urban and Fisher.
⁵https://biodifferences.com/difference-between-humoral-and-cell-mediated-immunity.html
⁶Cameron, J. (Producer, Director). 1991. Terminator 2: Judgment Day. United States: TriStar Pictures.
⁷Tortora, G., Grabowski, S. (1996). Principles of Anatomy and Physiology (8^th ed.), p. 688. New York: HarperCollins College Publishers.
⁸Reagan, Pres. Ronald. “Normandy Speech.” June 6, 1984.

In prior posts, I’ve talked about the difference between edema and lymphedema (click here & here to see those posts). Today, let’s take a look at conditions that begin as edema & can become lymphedema as the swelling persists.  How can that happen?

To understand how edema can become lymphedema, we need to revisit what lymphedema is.  By definition, true lymphedema is an accumulation of protein-rich fluid (tissue which has excess protein in it).  How does protein get into fluid?  You eat protein (like meat, eggs, etc.), but your body also makes proteins that play an essential role in bodily function.  I won’t get into the bio-physiology of proteins except to comment on one: a plasma (blood) protein called albumin.

Albumin helps regulates which way fluid goes, into the blood vessels or into the tissue to potentially cause swelling (known as “colloid osmotic pressure”). Albumin, which is made by the liver, accounts for 70% of the colloid osmotic pressure.^1,2  That’s huge!

Second, by definition, true lymphedema is the result of damage to the lymphatic system. How does the system get damaged? Genetic causes (called primary lymphedema) or trauma (called secondary lymphedema).  Trauma is the most common. Chronic edema can be considered trauma because it increases the amount of fluid the lymphatic system must transport out of your tissue & back to the heart over time (sort of like abusing the lymphatic system).

Your lymphatic system has a pump, little “hearts” called lymph angions. Just as your heart pumps blood, these angions pump lymph fluid. But while the heart is a closed, circulatory system, the lymphatic system carries fluid one way, from the tissue spaces (throughout the entire body) to the heart. Just as blood enters the heart, stretching the wall of the right atrium & causing it to contract, fluid enters a lymph angion, stretching its wall & causing it to contract. At rest, contractions are 6-10 times per minutes. When necessary, this pumping can increase up to 20 times per minute.⁴ However, just like with the heart, such endurance cannot be sustained indefinitely.  The lymph angion will fail & stop working. ⁵ When that happens, the lymphatic load remains in the tissue causing inflammation & scarring. This leads to an important point: 

Lymphedema is not reversible once damage has occurred because of the mechanical, structural changes that have taken place. Progression of the condition can be stopped & symptoms can be improved, but the anatomy cannot be like it was before the damage.

In acute injury or initial trauma, edema is present & the lymphatic system is pumping as hard as it can to remove the excess fluid.  The body usually recovers, the swelling inundation subsides & the lymphatics return to normal. But over time (such as with chronic edema), the lymph system becomes overwhelmed & eventually stops working.  When that happens, inflammation & scarring occur.  The system becomes mechanically & structurally damaged in the area of congestion.

Now that we’ve reviewed what lymphedema is, what are some causes of chronic edema & why can they cause secondary lymphedema?

Obesity, lipedema & other fat disorders

These conditions slow down the flow of lymphatic fluid. I often use the analogy of driving around a mountain. Because of the curves & narrow roads, you have to slow your speed. When there are several cars, congestion results. When lymphatic vessels must weave through fat tissue, lymph fluid can become sluggish & congestion results, creating a backup of fluid which can lead to scarring of the lymphatic vessels.

Additionally, fat (or adipose) causes inflammation itself & inflammation can cause more fat development. Inflammation is the body’s response to trauma which increases blood flow to the affected (which increases swelling in that area). The cycle continues.

Venous pressure

Venous pressure causes an increase in the lymphatic load.  Conditions such as chronic venous insufficiency or varicose veins are conditions which cause blood flow to regurgitate in the lower legs instead of efficiently making its way northward to the heart. 

Another source of increased venous pressure is positioning.  Feet remaining in a dependent position (hanging down) for extended periods such as jobs requiring long episodes of standing or sitting create significant pressure in the lower legs that must be overcome.  Both the amount and speed of blood flow decrease in the legs after 15 minutes of static, dependent positioning.⁶

Another source of venous pressure is inactivity or not contracting muscles (even if in a gravity neutral position) as is seen in paralysis after spinal cord injury or a stroke. The lymph system is not able to overcome the increased tissue pressure in these cases & eventually fails, leading to scarring.

Organ dysfunction

Conditions such as heart failure, kidney failure, thyroid impairment & liver disease all can create an excessive amount of fluid⁷ & an inability of the lymph system to keep up with the demands, resulting in fatigue & eventual scarring of lymphatic vessels.

Infection

Localized infection such as cellulitis (particularly when repeated infections occur) result in scarring of lymphatic vessels.

Diabetes

Diabetes causes changes in the smallest parts of your blood vessels (making up the capillary beds).  The capillary bed wall thickens & enlarges, allowing the exit of blood matter (water, proteins & other molecules) that would not otherwise exit. That creates an added burden for the lymphatic vessels to manage. ⁸ Additionally, in my own thinking, because this results in loss of blood flow to other areas, it may likely cause disease of lymphatic vessels themselves. Either case would eventually cause scarring.

One of roles of the lymphatic system includes maintaining homeostasis (preventing swelling). Anything that causes edema creates more work for the lymphatic system. And when you work, work, & work more without rest, you get tired. So does your lymphatic system. When the lymphatic system gets tired, the fluid, protein & other molecules it’s responsible for get left in the tissue. That causes an inflammatory response which creates a cascade of events that create a cycle of chronic inflammation & scarring called lymphedema. As the cycle continues, you begin to see the symptoms of lymphedema.  In all the cases mentioned above, lymphedema occurs as a result of structural, mechanical damage to the lymphatic vessels, rendering it ineffective as a result of being overtaxed.

Note: Check out this link to read more on what is being done to increase awareness of edema induced lymphedema (added 01/12/21)

What can you do to prevent lymphedema resulting from chronic edema? Manage your health condition &, if your doctor approves, get compression. Check out past blogs for posts on compression!

¹ https://www.ncbi.nlm.nih.gov/books/NBK531504/, https://en.wikipedia.org/wiki/Oncotic_pressure
² https://www.ncbi.nlm.nih.gov/books/NBK204/
³ https://www.mayoclinic.org/diseases-conditions/cirrhosis/symptoms-causes/syc-20351487
⁴ Weissleder, H., Schuchhardt, C. (2008).  Lymphedema Diagnosis and Therapy (4^th ed.), p.36.  Germany: Viavital Verlag GmbH.
⁵ Foldi, M, Foldi, E. (2006). Foldi’s Textbook of Lymphology (2^nd ed.), p. 201. Germany: Urban & Fisher.
⁶ Foldi, M, Foldi, E. (2006). Foldi’s Textbook of Lymphology (2^nd ed.), p. 434. Germany: Urban & Fisher.
7 Foldi, M, Foldi, E. (2006). Foldi’s Textbook of Lymphology (2^nd ed.), p. 242-259, . Germany: Urban & Fisher.

There are three primary methods for treating cancer.  These are surgery, chemotherapy (“chemo” for short) & radiation.  Sometimes these methods may be combined.  Depending on the type of cancer, additional treatment options might include bone marrow transplant, hormone therapy, molecular-targeted therapy, clinical trials & unconventional methods.

Surgery – Tumors may be removed or shrunk through surgery (often followed by chemo &/or radiation to treat any cells that may have spread).  This surgery is localized to the tumor site & might be done with the old-fashioned surgical knife.  However, there are also less extensive surgeries such as sentinel node biopsy, minimally invasive (like laparoscopy or thoracoscopy) & organ-preserving (e.g. lumpectomy). Newer approaches to destroy tumor tissue include focused sound waves (i.e. ultrasound), cold (cryotherapy), radiowaves (radiofrequency ablation) & light (phototherapy).

Chemotherapy – A drug or combination of drugs primarily administered orally, through injection or through a vein (via a catheter such as a PICC line or a port (i.e. a device placed under your skin on the chest).  Chemo is a systemic treatment, meaning it affects the whole body.  It targets fast-growing cells which include not only cancer cells but other fast-growing cells like skin, hair, bone marrow (including white or red blood cells & platelets) & cells that line your digestive tract (such as stomach & mouth).  Fortunately, the side effects from damage to healthy cells (such as nausea or diarrhea) can often be managed during treatment & other side effects (such as hair loss, dry skin or skin rash) usually go away.

Radiation – High-energy radiation is delivered to the tumor(s) by a machine via an external beam (i.e. X-Ray or gamma ray) or internally (via radioactive material placed in the body near the tumor or via systemic administration called brachytherapy).  The purpose of radiation is to shrink or kill the cancer cells by damaging their DNA. Unfortunately, normal cells can also be damaged leading to long-term effects such as fibrosis & lymphedema. However, doctors have an idea of how much radiation normal tissue can receive & take this into consideration when planning your treatment course.

References
www.cancer.org
Coleman, Norman, MD (2006). Understanding Cancer, p. 85-106. Baltimore: The John Hopkins University Press.

In March’s blog, we discussed what cancer is.  We said,

“When a cell is told to multiply, it begins a multi-step process which has “checkpoints.”  These checkpoints inspect the cell, ensure it is progressing normally & allow it to continue its development.  If a cell is found defective (i.e. several genes have changed or mutated), it will usually self-destruct or it will be removed by other cells (thanks to our immune system).  This process is programmed so there is a balance between the cells that multiply & those that die.   In cancer, however, this process is defective.  Instead of self-destructing or being removed, the defective cell passes through the checkpoints & multiplies at-will.”

This describes one reason people get cancer: Cells malfunction (usually as a result of age or genetic predisposition).  However, environmental factors may also contribute.  For example, chemicals found in pesticides or in cigarettes (or other forms of tobacco use).  UV radiation from too much sun exposure or sunburns has been linked to cancer development.  Behavioral factors may also increase risk.  For example, an unhealthy diet & sedentary lifestyle can lead to obesity* which increases the risk of developing cancer.  Smoking, heavy/regular alcohol consumption, chronic stress & hormones (such as menopausal therapy or oral contraceptives) do as well.

*Obesity & other conditions that cause chronic inflammation (such as chronic inflammatory bowel diseases – e.g. Crohn’s Disease – or even untreated lymphedema) has been linked to cancer.  The longer chronic inflammation persists, the greater the risk of cancer development.

References
http://www.cancer.gov/about-cancer/understanding/what-is-cancer
http://www.cancer.gov/about-cancer/causes-prevention
https://www.mdanderson.org/publications/focused-on-health/december-2014/how-stress-affects-cancer-risk.html.html

If you or someone you know has been given a diagnosis of breast cancer, you may have heard unfamiliar terms like “in situ,” “ductal,” “invasive,” “lobular,” “inflammatory” & “carcinoma.”  What do these words mean?

When the breast creates milk, it begins in a lobule.  Once the lobule develops milk, the liquid flows through the milk ducts & exits through the nipple.  When cancer cells develop in one of these areas, the cells may stay within that site or they may invade other parts of the breast tissue.  “In situ” & “invasive” describe what the cancer cells have done.  If the cancer has not spread to surrounding breast tissue, it is said to be “in situ” (i.e. in its original site).  If the cancer has spread beyond the borders of its original location & invaded surrounding breast tissue, it is said to be “invasive.”  The words describing the involved breast area & what the cancer cells have done are combined to form the name of a particular type of breast cancer:

• Ductal – refers to the milk ducts of the breast
  • ductal carcinoma in situ (or DCIS for short) means the tumor (or cancer mass) is contained within the milk ducts
  • invasive ductal carcinoma (or IDC for short) means the tumor growth has broken through the duct wall & spread to the surrounding breast tissue
• Lobular – refers to the lobule milk glands
  • lobular carcinoma in situ (or LCIS for short) means cells that look like cancer are growing in the milk glands; this type isn’t considered cancer yet – it is, however, a condition that needs to be watched
  • invasive lobular carcinoma (or ILC for short; also called “infiltrating lobular carcinoma”) means the tumor growth has broken through the lobule wall & spread to the surrounding breast tissue

For a diagram of the breast anatomy & above types of cancer, click: http://www.breastcancer.org/pictures/types

More terms

• carcinoma – refers to any cancer that begins in the skin or other tissue that cover organs
• inflammatory – refers to the description of inflammatory symptoms accompanying this type of cancer (tenderness, warmth, redness, swelling, &/or an orange-peel appearance to the skin).
  • inflammatory breast cancer (or IBC for short) means an inflammatory response within the breast tissue caused by cancer cells blocking the flow of lymph fluid.  Note: While an antibiotic should improve symptoms caused by an infection or mastitis, it will not help this condition. Be sure to notify your doctor if you’ve been prescribed an antibiotic but your symptoms haven’t gone away.

It’s worth noting there are other types of breast cancer not mentioned.  A comprehensive list includes:

ductal carcinoma in situ
invasive ductal carcinoma
lobular carcinoma in situ
invasive lobular carcinoma
inflammatory
medullary
mucinous or colloid
Paget’s disease

and even less common:
tubular
cribiform
papillary
micropapillary
apocrine
adenocystic
carcinosarcoma
squamous
sarcoma

References
Kneece, Judy, RN, OCN (2012). Breast Cancer Treatment Handbook (8^th ed), p 20-21, 66. South Carolina: EduCare
www.cancer.org
www.breastcancer.org

In our last blog, we described what cancer is.  In this blog, we’ll outline the different types of cancer (listed below).  A starting point to understanding the different types of cancer is to understand how a particular type of cancer gets its name.  Cancers are named based on their appearance & what part of the body they originate in.  For example, breast cancer is named “breast cancer” because the cancer is located in breast tissue.  Lung cancer is named “lung cancer” because the cancer is located in lung tissue & so on.  It’s important to note, however, that even if the cancer progresses (i.e. metastasizes) to other body parts, it is still named based on its original location.  For example, breast cancer which has metastases that go to the lung(s) isn’t called “lung cancer,” it’s called “metastatic breast cancer.”

Breast Cancer – the number one cause of lymphedema in the United States

• Ductal carcinoma in situ
• Lobular carcinoma in situ
• Invasive ductal carcinoma
• Invasive lobular carcinoma
• Inflammatory breast cancer

Lung Cancer

• Small-cell lung cancer
• Non-small-cell lung cancer

Skin Cancer

• Melanoma
• Basal cell carcinoma
• Squamous cell carcinoma
• Neuroendocrine carcinoma

Gastrointestinal Cancer

• Esophageal
• Stomach
• Liver
• Pancreas
• Colon & Rectum

Genitourinary Cancers (cancer of sexual organs & urinary organs)

• Prostate
• Cervix
• Bladder
• Kidney

Hematological Cancers (cancer of the blood & stem cells)

• Leukemia
• Lymphoma
• Multiple Myeloma

Head & Neck Cancers

• Oral cavity
• Nasal cavity
• Thyroid gland
• Pharynx

Sarcomas (cancerous tumors of soft tissue & bone anywhere in the body)

• Osteosarcomas (primary bone sarcomas)
• Soft tissue sarcoma (such as tumors arising from fat tissue, muscles, nerves, blood vessels, etc.)

Brain & Spinal Cord Tumors

• Glioma (tumors that start in glial cells)
• Meningioma (tumors that start in the outer lining of the brain)
• Acoustic Neuromas & Schwannomas (tumors that develop from Schwann cells – which line the cranial & peripheral nerves)
• Medulloblastoma (which arise from fetal cells in the cerebellum; more commonly found in children but they can be found in adults)

http://www.cancer.org/cancer/showallcancertypes/index
Smith-Gabai, Helene (2011).  Occupational Therapy in Acute Care, p. 416-426.  Maryland: The American Occupational Therapy Association, Inc.
Coleman, Norman, MD (2006). Understanding Cancer, p. 43-45. Baltimore: The John Hopkins University Press.