What is the Difference Between Mastocytosis and MCAS

The key difference between mastocytosis and MCAS is that mastocytosis is a condition caused by an excess number of mast cells gathering in the tissues of the body, while MCAS is a condition in which the mast cells in the body release an inappropriate amount of chemicals into the body.

Mastocytosis and MCAS are two different types of mast cell diseases. Mast cell diseases are rare conditions. People with mast cell diseases may experience unexplained flushing, abdominal pain, bloating, severe reactions to foods, medicines, or insect stings. These people may feel hot even when in a room with a normal temperature. These symptoms could also signal an allergic reaction.

CONTENTS

1. Overview and Key Difference
2. What is Mastocytosis  
3. What is MCAS
4. Similarities – Mastocytosis and MCAS
5. Mastocytosis vs MCAS in Tabular Form
6. Summary – Mastocytosis vs MCAS

What is Mastocytosis?

Mastocytosis is a condition that is caused by excess mast cells gathering in the tissues of the body. There are two main types of mastocytosis: cutaneous mastocytosis and systematic mastocytosis. Cutaneous mastocytosis mainly affects children. In cutaneous mastocytosis, mast cells gather in the skin but are not found in large numbers elsewhere in the body. On the other hand, systematic mastocytosis mainly affects adults. In systematic mastocytosis, mast cells gather in body tissues, including skin, internal organs, and bones.

The symptoms of cutaneous mastocytosis include abnormal growths (lesions) on the skin such as bumps, spots, or blisters. The symptoms of systematic mastocytosis include flushing, itching, hives, abdominal pain, diarrhoea, nausea, vomiting, anemia, bleeding disorders, bone and muscle pain, enlarged liver, spleen, or lymph nodes, depression, mood changes, or problems in concentrating. People with mastocytosis also face a high risk of developing severe allergic reactions called anaphylaxis.

The cause of mastocytosis is the KIT gene mutation, which makes mast cells more sensitive to the effects of a signalling protein called stem cell factor (SCF). SCF plays a role in stimulating the production and survival of mast cells inside the bone marrow. Moreover, this condition can be diagnosed through skin biopsies, blood tests, ultrasound, DEXA scans to measure bone density, and bone marrow biopsy tests. Furthermore, mastocytosis can be treated with steroid creams, antihistamines, epinephrine, other medications (relive diarrhoea and stomach pain), and ultraviolet light.

What is MCAS (Mast Cell Activation Syndrome)?

MCAS (mast cell activation syndrome) is a condition in which mast cells in the body release an inappropriate amount of chemicals into the body. This disease may cause severe allergic reactions and other symptoms. MCAS is normally idiopathic. But MCAS can occur due to genetic changes such as somatic mutations in KIT, MC regulatory genes, and inherited increased copy number of TPSAB1 gene.

The symptoms of this condition include itching, flushing, hives, easy bruising, reddish complexion, burning feeling, dermatographism, light-headedness, dizziness, presyncope, syncope, arrhythmia, tachycardia, diarrhoea, nausea, vomiting, cramping, intestinal discomfort, constipation, swallowing difficulties, throat tightness, congestion, coughing, wheezing, and anaphylaxis. This condition is usually diagnosed through serum tests for the level of mast cell tryptase and urine tests for levels of N-methylhistamine, 11B-prostaglandin F2 α, or leukotriene E4. Furthermore, treatments for MCAS include H1 and H2 antihistamines, aspirin, mast cell stabilizers, antileukotrienes, and corticosteroids.

What are the Similarities Between Mastocytosis and MCAS?

• Mastocytosis and MCAS are two different types of mast cell diseases.
• Both are rare conditions.
• Severe allergic reactions such as anaphylaxis can be present in both conditions.
• Both conditions are treatable with antihistamines.

What is the Difference Between Mastocytosis and MCAS?

Mastocytosis is a condition caused by an excess of mast cells gathering in the tissues of the body, while MCAS (mast cell activation syndrome) is a condition in which the mast cells in the body release an inappropriate amount of chemicals into the body. Thus, this is the key difference between mastocytosis and MCAS. Furthermore, the disease incidence of mastocytosis is 5-10 per 1,000,000 people, while the disease incidence of MCAS is 2.7 per 1,000,000 people.

The below infographic presents the differences between mastocytosis and MCAS in tabular form for side by side comparison.

Summary – Mastocytosis vs MCAS

The three major forms of mast cell diseases are mastocytosis, mast cell activation syndrome (MCAS), and alpha tryptasemia (HAT). Mastocytosis is a condition that is caused by an excess number of mast cells gathering in the tissues of the body, while MCAS (mast cell activation syndrome) is a condition in which the mast cells in the body release an inappropriate amount of chemicals into the body. So, this summarizes the difference between mastocytosis and MCAS.

Reference:

1. “Mastocytosis & Mast Cells: Symptoms & Treatment.” Cleveland Clinic.
2. “Mast Cell Activation Syndrome: Symptoms, Causes, and Treatment.” WebMD.

Image Courtesy:

1. “Mastocytosis2019” By Doc James – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Blausen 0018 Anaphylaxis” By Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia