While it can be disconcerting to discover that you've developed a line of bumps on your skin, in many cases, the cause of these bumps is identifiable and treatable. In many cases, they result from infectious or allergic causes. If you're concerned about bumps, you should see your doctor, who can do a physical exam and order tests -- if needed -- to diagnose your condition. Treatment may be as simple as taking a short course of medication or applying a cream to the affected area.
While there are many specific causes of bumps on the skin, the general process underlying bump formation is relatively constant. That is, if your skin comes into contact with something it considers foreign, say Kim Barrett and colleagues in "Ganong's Review of Medical Physiology," it will release molecules that cause the circulation to become leaky and to recruit immune cells that help to defend your system from the foreign stiumulus. This leads to the characteristic red, raised appearance of many bumps on your skin.
Causes of Bumps
Many, many things can cause a line of bumps to appear on your skin. In trying to determine what's caused your bumps, you should ask yourself what you were doing before the bumps appeared? If you've just returned from a hike in the woods, you could be experiencing poison ivy or poison oak. Under what circumstances did the bumps appear? Bumps that appear in a linear pattern across a patch of skin that was painful for two or three days prior to the bumps' emergence may be reactivation of the virus that causes chicken pox. A doctor can ask you these questions, and others, to help determine the cause of your symptoms.
Viruses and Parasites
Many different viruses and parasites can cause bumps to appear on your skin. For example, according to Wayne Shandera and Shruti Patel writing in "Current Medical Diagnosis and Treatment," varicella zoster, the virus that causes chicken pox, can reactivate years after the initial infection has subsided, occasionally during periods of stress or immunosuppression -- for example, if you are on steroids for a separate disease. Another virus, herpes, and a parasite, scabies, can also cause lines of bumps on your skin, although their presentations differ somewhat from zoster's.
If you developed your bumps after coming into contact with something new, or something known to be allergenic such as poison ivy, you may be experiencing contact dermatitis. This is a kind of allergy that develops when immune cells in your skin are hyper-sensitive to a certain stimulus, say Calvin McCall and Thomas Lawley in "Harrison's Principles of Internal Medicine." Common man-made stimuli that cause contact dermatitis are latex, fabric detergent, and some fabrics.
Treatment of your bumps will depend on identifying their cause. For example, bumps caused by reactivation of a viral infection are typically treated with antiviral medications, and in some cases, recurrent outbreaks can be prevented by taking daily suppressive medications. In contrast, bumps caused by allergic contact dermatitis are typically treated with topical steroid creams, and reoccurrances are prevented by avoiding the allergic stimulus.