Systemic mastocytosis

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Systemic mastocytosis is a blood disorder that can affect many different body systems. Individuals with the condition can develop signs and symptoms at any age, but it usually appears after adolescence.

Signs and symptoms of systemic mastocytosis often include extreme tiredness (fatigue), skin redness and warmth (flushing), nausea, abdominal pain, bloating, diarrhea, the backflow of stomach acids into the esophagus (gastroesophageal reflux), nasal congestion, shortness of breath, low blood pressure (hypotension), lightheadedness, and headache. Some affected individuals have attention or memory problems, anxiety, or depression. Many individuals with systemic mastocytosis develop a skin condition called urticaria pigmentosa, which is characterized by raised patches of brownish skin that sting or itch with contact or changes in temperature. Nearly half of individuals with systemic mastocytosis will experience severe allergic reactions (anaphylaxis).

There are five subtypes of systemic mastocytosis, which are differentiated by their severity and the signs and symptoms. The mildest forms of systemic mastocytosis are the indolent and smoldering types. Individuals with these types tend to have only the general signs and symptoms of systemic mastocytosis described above. Individuals with smoldering mastocytosis may have more organs affected and more severe features than those with indolent mastocytosis. The indolent type is the most common type of systemic mastocytosis.

The severe types include aggressive systemic mastocytosis, systemic mastocytosis with an associated hematologic neoplasm, and mast cell leukemia. These types are associated with a reduced life span, which varies among the types and affected individuals. In addition to the general signs and symptoms of systemic mastocytosis, these types typically involve impaired function of an organ, such as the liver, spleen, or lymph nodes. The organ dysfunction can result in an abnormal buildup of fluid in the abdominal cavity (ascites). Aggressive systemic mastocytosis is associated with a loss of bone tissue (osteoporosis and osteopenia) and multiple bone fractures. Systemic mastocytosis with an associated hematologic neoplasm and mast cell leukemia both involve blood cell disorders or blood cell cancer (leukemia). Mast cell leukemia is the rarest and most severe type of systemic mastocytosis.

Individuals with the milder forms of the condition generally have a normal or near normal life expectancy, while those with the more severe forms typically survive months or a few years after diagnosis.

ORPHANET DEFINITION A heterogeneous group of rare, acquired and chronic hematological malignancies related to an abnormal accumulation/proliferation of neoplastic mast cells (MCs) in one or several organs, mainly the bone marrow (BM), associated frequently with skin involvement.

Inheritance

From: MedlinePlus Genetics, National Library of Medicine

Not inherited

Frequency in the source

From: MedlinePlus Genetics, National Library of Medicine

Annual incidence: 1-9 / 1 000 000; Italy; Value and class. Point prevalence: 1-5 / 10 000; Worldwide; Class only. Annual incidence: 1-9 / 1 000 000; Denmark; Value and class. Point prevalence: 1-9 / 100 000; Denmark; Value and class.

Understanding terms used in the source

These definitions explain medical words used above. A definition is not evidence that another condition is present, and it does not predict how a symptom will develop. Ask the clinician which terms apply to the actual examination or test result.

Gastroesophageal reflux

A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter.

Nasal congestion

Reduced ability to pass air through the nasal cavity often leading to mouth breathing.

Abdominal pain

An unpleasant sensation characterized by physical discomfort (such as pricking, throbbing, or aching) and perceived to originate in the abdomen.

Mastocytosis

The presence of an increased number of mast cells and CD34+ mast cell precursors in the body.

Osteoporosis

Osteoporosis is a systemic skeletal disease characterized by low bone density and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility. According to the WHO criteria, osteoporosis is defined as a BMD that lies 2.5 standard deviations or more below the average value for young healthy adults (a T-score below -2.5 SD).

When it may begin

From: MedlinePlus Genetics, National Library of Medicine

All ages

Inheritance in the source

From: MedlinePlus Genetics, National Library of Medicine

Not inherited

Frequency and the population described

From: MedlinePlus Genetics, National Library of Medicine

Annual incidence: 1-9 / 1 000 000; Italy; Value and class. Point prevalence: 1-5 / 10 000; Worldwide; Class only. Annual incidence: 1-9 / 1 000 000; Denmark; Value and class. Point prevalence: 1-9 / 100 000; Denmark; Value and class.

Which doctor should you see?

The suggested department for discussing Systemic mastocytosis is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Systemic mastocytosis. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.