Table 2.

Common symptoms and findings in mast cell activation syndrome (MCAS). Most are chronic and low-grade, some are persistent, but many are either episodic or waxing/waning. More comprehensive lists [53] and discussions [54] are available.

System	Potential Manifestations of Mast Cell Activation Syndrome (MCAS)
Constitutional	Fatigue, subjective or objective hyperthermia and/or hypothermia, sweats, flushing, plethora or pallor, increased or decreased appetite, weight gain or loss, pruritus, chemical/physical sensitivities (often odd), and poor healing
Dermatologic/integument	Rashes/lesions of many sorts (e.g., classic urticaria pigmentosa, telangiectasias, xerosis, striae, warts, tags, folliculitis, ulcers, dyshydrotic eczema, and migratory but sometimes focally persistent patchy macular erythema), migratory pruritus (sometimes aquagenic), angioedema, dermatographism, alopecia, and onychodystrophy
Ophthalmologic	Irritated eyes, episodic difficulty focusing, and lid tremor/tic (blepharospasm)
Otologic/osmic	Infectious or sterile otitis externa and/or media, hearing loss and/or tinnitus, dysosmia, coryza, congestion, and epistaxis
Oral/oropharyngeal	Pain or irritation (sometimes “burning”), leukoplakia, ulcers, angioedema, dysgeusia, and dental or periodontal inflammation/decay
Lymphatic	Adenopathy (usually sub-pathologic and spontaneously waxing/waning in size, sometimes migratory), adenitis, and splenitis
Pulmonary	Airway inflammation at any or all levels, cough, dyspnea (usually mild, episodic, and “just cannot catch a deep breath” despite normal pulmonary function tests), wheezing, obstructive sleep apnea, and pulmonary hypertension
Cardiovascular	Presyncope or syncope, hypertension and/or hypotension, palpitations, migratory edema, chest pain (usually non-anginal), atherosclerosis, odd heart failure (e.g., takotsubo), allergic angina (Kounis syndrome), and vascular anomalies
Gastrointestinal	Dyspepsia, reflux, nausea, vomiting (sometimes cyclical), diarrhea and/or constipation (often alternating), angioedema, dysphagia (often proximal), bloating/gas, migratory abdominal pain from luminal or solid organ inflammation, malabsorption, and ascites
Genitourinary	Migratory luminal and solid organ inflammation, chronic kidney disease, endometriosis, chronic back/flank/abdominal pain, infertility, and decreased libido; miscarriages may signal an MCAS-rooted anti-phospholipid antibody syndrome
Musculoskeletal	Migratory bone/joint/muscle pain, joint laxity/hypermobility, and osteopenia and/or osteosclerosis
Neurologic	Headache, sensory and/or motor neuropathies, seizure disorders, pseudoseizures, and dysautonomia
Psychiatric	Mood disturbances, anxiety/panic, psychoses, cognitive dysfunction (most commonly memory and word-finding difficulties), and sleep disruption
Endocrinologic/metabolic	Abnormal electrolytes and liver function tests, hypo- or hyperthyroidism, dyslipidemia, impaired glucose control, hyperferritinemia, nutritional deficiencies, delayed puberty, and dysmenorrheal
Hematologic/coagulopathic	Polycythemia or anemia (macrocytic, normocytic, or microcytic), leukocytosis or leukopenia, monocytosis or eosinophilia or basophilia, thrombocytosis or thrombocytopenia, arterial and/or venous thromboembolic disease, and otherwise inexplicable “easy” bruising/bleeding; usually no histologic or molecular evidence of MC aberrancy in the marrow in MCAS
Immunologic	Hypersensitivity reactions, increased risk for malignancy and autoimmunity, impaired healing, increased susceptibility to infection, increased or decreased levels of immunoglobulin of any isotype, and monoclonal gammopathy of undetermined significance