Table 4.
MCAS Mimickers: Differential Diagnoses to MCAS *.
| Disorder/Mimicker | Clinical Findings/Symptoms Presenting as Mimicry |
| Cardiovascular Mimickers | |
| Myocardial Infarction | Hypotension, Shock, Syncope |
| Endocarditis/Endomyocarditis | Hypotension, Shock |
| Aortic Stenosis with Syncope | Syncope |
| Pulmonary Infarction | Dyspnea, Hypotension |
| Endocrinologic Mimickers | |
| Acute Hypothyroidism | Hypotension, Shock |
| Acute Hypoglycemia | Hypotension, Shock |
| Adrenal Insufficiency | Hypotension, Shock |
| Hypopituitarism | Hypotension, Shock |
| Gastrointestinal Mimickers | |
| Acute Inflammatory Bowel Disease | Diarrhea, Pain, Dehydration, Hypotension |
| VIP-secreting Tumor (VIPoma) | Diarrhea, Dehydration, Hypotension |
| Active Crohn’s Disease or Colitis Ulcerosa | Diarrhea, Pain, Dehydration, Hypotension |
| Food Intoxication | Diarrhea, Dehydration, Hypotension |
| Infectious Disease Mimickers | |
| Severe Bacterial or Viral Infections | Septic Shock |
| Acute Gastrointestinal Infection | Diarrhea, Cramps, Dehydration, Hypotension |
| Acute Encephalitis / Meningitis | Headache, Confusion, Fatigue, Hypotension |
| Acute Parasitic Diseases (e.g., Acute Chagas Disease) | Dehydration, Rash, Hypotension |
| (e.g., Acute Chagas Disease) | Headache, Dyspnea, Hypotension |
| Neurologic/Central Nervous System (CNS) Mimickers | |
| Epilepsy | Headache, Confusion, Fatigue, Shock |
| CNS Tumors | Headache, Confusion, Fatigue, Hypotension |
| Other CNS Diseases | Headache, Fatigue, Hypotension |
| Intoxication | Headache, Confusion, Fatigue, Hypotension |
| Somatoform disorders | Headache, Fatigue, Hypotension |
| Psychiatric conditions | Headache, Confusion, Fatigue, Hypotension |
| Cutaneous Mimickers | |
| Hereditary or Acquired Angioedema | Angioedema, Rash, Hypotension |
| Acute Lupus Erythematosus | Rash, Headache, Fatigue |
| Acute Toxic Dermatoses | Exanthema, Hypotension |
| Hematologic Mimickers: Acute Anemia | |
| Acute Gastrointestinal Bleeding | Hypovolemic Shock |
| Massive Hypermenorrhea | Hypovolemic Shock |
| Drug-related Mimickers (Adverse Events after Drug Intake) | |
| Drug-induced Hypoglycemia | Fatigue, Loss of Consciousness |
| Drug-induced Hypotension | Hypotension, Shock |
| Drug-induced Diarrhea | Diarrhea, Cramps, Dehydration, Hypotension |
| Drug-Induced CNS Damage | Headache, Fatigue, Hypotension, Confusion |
* In most instances, symptoms of acute hypotension are recorded. If additional MCA-mimicking symptoms, such as skin lesions, headache and/or diarrhea are found, it is often difficult to separate the pathology from MCA and thus MCAS. Abbreviations: MCA, mast cell activation; MCAS, MCA syndrome; VIP, vasoactive intestinal peptide.