Upon getting your child ready for bed, you draw them a nice warm bath. When you take them out of the tub, though, they've got a red, raised bump that looks like a bug bite on their back, belly, arm, or leg. You know that this mark wasn't there when you put your child in the bath, so what could it be? What could have possibly bitten your child while they were in the bathtub?

Nothing bit your child. The bug bite-like blemish that you see on their body is mastocytosis -- a rare condition characterized by an overabundance of mast cells.

Understanding Mast Cells

Mast cells are located all over the skin, in the stomach, and in the intestines. They're produced by bone marrow and they play a crucial role in healing wounds and defending the body against infection. When triggered by an irritant, mast cells release histamine. 

The histamine's job is to open up the blood vessels so that white blood cells can easily travel by the masses to the irritated skin. Histamine also prompts fluid to be released at the site of irritation in an effort to wash away the irritant.

Mast cells, along with the histamine they produce, play such a vital role in the body's immune system that some scientists believe that there's no way a person could survive without ample quantities of them.

Too Much Of A Good Thing

Mastocytosis occurs when too many mast cells congregate in one particular place, making that region of the body susceptible to the side-effects of an overactive immune system.

Under normal conditions, mast cells are triggered to release histamine only by true threats, such as insect bites, snake venom, or poisonous plants. In a person with mastocytosis, however, temperature fluctuations, stress, certain foods, and even gentle rubbing on the affected area can cause histamine levels to surge.

When you placed your child in the bath, either the temperature of the water or the way in which the washcloth stimulated his or her skin resulted in a histamine release, and that histamine release resulted in the red, raised, possibly itchy spot on your child's body.

When To Worry

If you go searching around on the Internet, you're going to find some scary stories about this condition. It's important for you to know that there is a big difference between adult and childhood mastocytosis. 

When excess mast cells are present in the bone marrow, they can travel to the stomach or intestines and cause abdominal pain, nausea, diarrhea, and/or ulcers. Although rare, mast cells are also capable of becoming cancerous.  

When present in adults, mastocytosis usually does affect the bone marrow, and therefore other organs of the body. In children, however, the risk of bone marrow involvement is far less. In fact, 70% percent of children who are diagnosed with mastocytosis show great improvement by the age of ten years old, without undergoing any treatment. 

Your Next Step

Schedule an appointment with your family's dermatology specialist to have your child examined. The dermatologist can run some blood work or perform a skin biopsy to determine whether or not the condition is present beyond the skin. If your child's condition does involve other organs, your dermatologist will recruit the help of specialty doctors and begin drafting a plan of care.

If your child gets red, raised bumps on their skin upon emerging from a bath, it's highly likely that they have a rare condition known as mastocytosis. Visit your dermatologist to ensure the problem is limited to their skin, and to discuss how to limit their symptoms by avoiding things that commonly trigger histamine release in mastocysosis sufferers.