| Autoimmune | Chronic granulomatous disease |
| Rheumatoid arthritis |
| Sarcoidosis |
| Cardiopulmonary | Coronary vasospasm (i.e., Prinzmetal angina) |
| Takayasu arteritis |
| Temporal (giant cell) arteritis |
| Endocrinologic | Carcinoid tumor |
| Diabetes mellitus or insipidus |
| Eosinophilic pneumonia |
| Hyperthyroidism |
| Hypogonadism, male |
| Menopause |
| Obstructive sleep apnea |
| Hematologic | Lymph node hyperplasia |
| Obesity |
| Pheochromocytoma |
| Polycythemia vera |
| Thrombocythemia, essential |
| Infection | Babesiosis |
| Cysticercosis |
| Endocarditis |
| HIV |
| Malaria |
| Mononucleosis |
| Pneumonia |
| Malignancy | Leukemia |
| Lymphoma |
| Tuberculosis |
| Miscellaneous | Chronic fatigue syndrome |
| Environmental factors |
| Gastroesophageal reflux disease |
| Inflammatory pseudotumor |
| Other neoplasm |
| Pregnancy/postpartum transition |
| Silicone breast implants |
| Neurologic | Anxiety disorder |
| Autonomic dysreflexia |
| Syringomyelia |
| Psychiatric | Depression |
| Panic disorder |
| Posttraumatic stress disorder |
