Human cells in every organ and body tissue have tightly controlled rates of growth and replication. Abnormalities that accelerate the normal rate of cell growth cause a range of diseases that vary from mild to severe. The skin, bone marrow and nervous system are among the many sites that may be affected by diseases associated with abnormal cell growth, which may be inherited or acquired during life.
Psoriasis
Psoriasis is a chronic, inflammatory skin condition characterized by a rapid growth rate of skin cells known as keratinocytes. The rate of skin regeneration in psoriasis is shortened from the normal 28 days to less than five days. Immune system cells called T cells stimulate the accelerated skin growth that occurs with psoriasis.
With the most common form of psoriasis, known as psoriasis vulgaris, accelerated skin cell growth occurs in discrete areas known as plaques, which appear as red, raised patches of skin with a scaly surface. Common sites of psoriatic plaques include the scalp, knees, lower back and elbows, although the lesions may form on any skin surface. Approximately 7.5 million adults and children in the United States have psoriasis, according to the American Academy of Dermatology, with Caucasians disproportionately affected.
Polycythemia Vera
Polycythemia vera is a condition characterized by abnormal growth and replication of erythrocyte-producing bone marrow cells, leading to an increased level of circulating red blood cells, or erythrocytes. The overabundance of red blood cells increases the blood thickness, causing sluggish flow and an increased risk for blood clot formation.
An acquired genetic abnormality--one not inherited but developing during a person's lifetime--causes primary polycythemia, according to the National Heart, Lung and Blood Institute. Secondary polycythemia vera can develop in response to chronic oxygen deprivation, such as occurs with severe chronic obstructive pulmonary disease or heavy smoking. Possible symptoms of polycythemia vera include a ruddy complexion, widespread itching after a hot bath or shower, excessive sweating, dizziness, weakness, shortness of breath, ringing in the ears, headache and visual disturbances.
Neurofibromatosis
Neurofibromatosis is a genetic disorder characterized by the abnormal growth of support cells that encircle and protect the nerves, leading to the formation of tumors. Types of neurofibromatosis include von Recklinghaus disease, or neurofibromatosis type 1, schwannomatosis and neurofibromatosis type 2. According to the National Institute of Neurological Disorders and Stroke, neurofibromatosis type 1 is the most prevalent form of the disease.
Most tumors associated with neurofibromatosis prove noncancerous but may require surgical removal because of encroachment on other vital structures or disfigurement. Although uncommon, neurofibromas can become cancerous, necessitating removal and possibly chemotherapy or radiation treatment.
References
- American Academy of Dermatology: Psoriasis
- PsoriasisNet: What is Psoriasis?
- "American Family Physician"; Polycythemia Vera; Brian J. Stuart, M.D., Anthony J. Viera, M.D.; May 2004
- National Heart, Lung and Blood Institute: Polycythemia Vera
- National Institute of Neurological Disorders and Stroke: Neurofibromatosis Fact Sheet
