Spots that look like freckles on a person's inner thighs or stomach is one typical symptom of systemic mastocytosis, according to the American Academy of Allergy, Asthma and Immunology. Other symptoms include low blood pressure, shortness of breath, anaphylaxis, fainting and headache. People with systemic mastocytosis may also experience nausea, diarrhea, uterine cramps, musculoskeletal pain and flushing.
Spots indicative of systemic mastocytosis are called urticaria pigmentosa, explains the American Academy of Allergy, Asthma and Immunology. If these spots become irritated, they begin to itch and transform into hives. Common sources of irritation include exposing the skin to any extreme change in temperature or stroking the skin around the urticaria pigmentosa.
Systemic mastocytosis is a disorder that causes mast cells to increase within the body, notes Mayo Clinic. Consuming alcohol or spicy foods, taking certain medications and temperature changes can all provoke the mast cells into releasing substances that trigger symptoms.
To diagnose systemic mastocytosis, a doctor orders blood and urine tests to verify the cause of the patient's symptoms, states Cancer.net. Bloodwork may indicate high levels of tryptase, which is sometimes indicative of systemic mastocytosis. These tests can also determine patient's current organ function. Doctors often require a skin biopsy to make a definitive diagnosis and may also order a bone marrow aspiration and biopsy to determine if the mastocytosis is systemic. Molecular testing helps determine any unique characteristics of the mast cells, and doctors use the results to recommend treatment options.