Hypereosinophilic syndrome

A heterogeneous group of disorders with the common feature of prolonged eosinophilia of unknown cause and associated organ system dysfunction, including the heart, central nervous system, kidneys, lungs, gastrointestinal tract, and skin. { There is an idiopathic form not otherwise characterized, but the group also includes Churg-Strauss syndrome, and a group of Eosinophil-Associated Gastrointestinal Disorders (EGID):

• Eosinophilic Esophagitis (EE): high numbers of eosinophils occurring in the esophagus. *Eosinophilic Esophagitis
• Eosinophilic Gastritis (EG): high numbers of eosinophils in the stomach.
• Eosinophilic Gastroenteritis (EGE): affects the stomach and small intestine.
• Eosinophilic Colitis (EC): describes the occurrence of high numbers of eosinophils in the large intestine.

The diagnosis requires:

• a peripheral eosinophil count of greater than 1.5 per microliter for longer than 6 months
• evidence of organ involvement, thus excluding benign eosinophilia
• an absence of other causes of eosinophilia, such as parasite infestation (most common cause of eosinophilia worldwide), allergy (most common cause of eosinophilia in the United States), malignancy, and collagen-vascular disease.

A support group reports three patients with the idiopathic form.

Pathology

There is a massive increase in the number of eosinophils in the blood, mimicking leukemia, and extensive eosinophilic infiltration of the various organs. Eosinophil production is known to be stimulated by interleukins.