Hyperplasia is an increase in the number of cells in an organ or tissue. Though this process is often harmless and sometimes even beneficial, it can also happen in connection with several illnesses. Generally speaking, all types of hyperplasia can be categorized as physiologic, or benign, and pathologic, or illness-related. This process can also be induced artificially. Regardless of whether its physiologic or pathologic, this process occurs in response to normal stimuli, as opposed to the processes that form tumors, which are abnormal stimuli.
Most people experience some type of harmless hyperplasia at some time during their lives. For instance, certain types of exercise can cause an increase in the number of muscle cells in a particular area, and pregnant women usually develop extra milk gland cells in their breasts in preparation for breastfeeding. It's also extremely common for older men to develop more cells in their prostate glands, which is known as benign prostatic hyperplasia. Some other physiologic types include focal nodular hyperplasia, which is a non-cancerous type of liver growth, and cutaneous lymphoid hyperplasia, a type of skin lesion. One rarer type is intravascular papillary endothelial hyperplasia, in which the cells lining blood vessels increase, usually in the skin of the head or neck.
Sometimes, the increase in cells is extremely beneficial. For example, this process is what allows the liver to regenerate itself even if it is extremely damaged. This is also the reason that liver transplants work — the cells in a section of donated liver can divide and increase to the point where the liver becomes functional again. Additionally, some people induce hyperplasia through injections of Insulin Growth Factor-1 (IGF-1) and Human Growth Hormone (HGH). Though this is not always dangerous, and it does tend to lead to lasting gains in muscle mass, overuse of IGF-1 and HGH is associated with the growth of breasts in men, carpal tunnel syndrome, premature baldness, aggression, and liver and kidney problems, among other things.
Though this process in and of itself usually isn't a dangerous condition, it is sometimes associated with illnesses and may be a precursor to some cancers. For instance, endometrial hyperplasia, which is an increase in the number of cells lining the uterus, is a risk factor for endometrial cancer, but can also happen in response to estrogen therapy or polycystic ovary syndrome (PCOS). Other types are more closely associated with cancer, such as C-cell hyperplasia, which is generally a precursor to medullary thyroid cancer (MTC), and oral verrucous hyperplasia, which is thought to be a precursor to verrucous carcinoma, a type of oral cancer.
Another pathologic type that is not associated with cancer is congenital adrenal hyperplasia (CAH), which affects the adrenal gland's ability to produce hormones such as cortisol and androgens. This is associated with Cushing's syndrome, and usually causes abnormal genitalia, extremely early puberty, infertility, menstrual irregularities, and severe acne. There are two forms of CAH, one of which starts in infancy and is generally more serious than the other, which starts in late childhood or early adolescence.
Symptoms and Diagnosing
The symptoms of this condition depend largely on the underlying cause. Since there are so many different types of this condition, there's no one overall method for diagnosing it, but doctors can generally determine whether a person has it by the associated symptoms or by taking and testing a sample of cells. A few types do have easily visible symptoms; for example, cutaneous lymphoid hyperplasia causes reddish-brownish nodules on the skin, and sebaceous hyperplasia causes shiny bumps on the face. Even in cases with visible symptoms, however, a doctor still usually needs a biopsy to confirm the diagnosis.
Like the diagnostic process, the treatment for hyperplasia depends on the type. In some cases, the treatment centers on the underlying cause, as with CAH, while in others hormonal injections can help. Any nodules and growths formed by this process are usually surgically removed.