Mastocytosis, a type of mast cell disease, is a rare disorder affecting both children and adults caused by the accumulation of functionally defective mast cells (also called mastocytes) and CD34+ mast cell precursors.People affected by mastocytosis are susceptible to a variety of symptoms, including itching, hives, and anaphylactic shock, caused by the release of histamine and other pro-inflammatory substances from mast cells. Signs and symptoms
When mast cells undergo degranulation, the substances that are released can cause a number of symptoms that can vary over time and can range in intensity from mild to severe. Because mast cells play a role in allergic reactions, the symptoms of mastocytosis often are similar to the symptoms of an allergic reaction. They may include, but are not limited to
Fatigue
Skin lesions (urticaria pigmentosa), itching, and dermatographic urticaria (skin writing)
"Dariers Sign", a reaction to stroking or scratching of urticaria lesions. Abdominal discomfort
Nausea and vomiting
Diarrhea
Olfactive intolerance
Ear/nose/throat inflammation
Anaphylaxis (shock from allergic or immune causes)
Episodes of very low blood pressure (including shock) and faintness
Bone or muscle pain
Decreased bone density or increased bone density (osteoporosis or osteosclerosis)
Headache
Depression
Ocular discomfort
Increased stomach acid production causing peptic ulcers (increased stimulation of enterochromaffin cell and direct histamine stimulation on parietal cell)
Malabsorption (due to inactivation of pancreatic enzymes by increased acid)
HepatosplenomegalyThere are few qualitative studies about the effects of mastocytosis on daily life. However, a Danish study from 2018 describes the multidimensional impact of the disease on everyday life. Pathophysiology
Mast cells are located in connective tissue, including the skin, the linings of the stomach and intestine, and other sites.
The most common SM (>90%)
Smouldering systemic mastocytosis (SSM)
Systemic mastocytosis with associated hematological neoplasm (SM-AHN)
Aggressive systemic mastocytosis (ASM)
Mast cell leukemia (MCL)

Treatment
There is no cure for mastocytosis, but there are a number of medicines to help treat the symptoms:

Anti-mediator therapy
Antihistamines block receptors targeted by histamine released from mast cells. Both H1 and H2 blockers may be helpful, often in combination. Leukotriene antagonists block receptors targeted by leukotrienes released from mast cells. Mast cell stabilizers help prevent mast cells from releasing their chemical contents. Cromoglicic acid is the only medicine specifically approved by the FDA for the treatment of mastocytosis. Ketotifen is available in Canada and Europe and more recently in the U.S. It is also available as eyedrops (Zaditor). Proton-pump inhibitors help reduce production of gastric acid, which is often increased in patients with mastocytosis. Excess gastric acid can harm the stomach, esophagus, and small intestine. Epinephrine constricts blood vessels and opens airways to maintain adequate circulation and ventilation when excessive mast cell degranulation has caused anaphylaxis. Salbutamol and other beta-2 agonists open airways that can constrict in the presence of histamine. Corticosteroids can be used topically, inhaled, or systemically to reduce inflammation associated with mastocytosis. Drugs to prevent/treat osteoporosis include Calcium-Vitamine D, bisphosphonates and in rare cases inhibitors of RANK-LAntidepressants are an important and often overlooked tool in the treatment of mastocytosis. Depression and other neurological symptoms have been noted in mastocytosis. Some antidepressants, such as doxepin and mirtazapine, are themselves potent antihistamines and can help relieve physical as well as cognitive symptoms.