[Eosinophilia--a challenging differential diagnosis].

BACKGROUND: Eosinophilia is not uncommon in clinical practice. The main causes are allergies and parasitic infections. Rarely, eosinophilia is associated with pulmonary affections, malignant tumors, gastroenteritis, and autoimmune diseases. A new classification based on pathophysiological data for the hypereosinophilic syndrome in order to simplify diagnosis and therapy was introduced in 2006.

CASE REPORT: A 22-year-old man was admitted to another hospital because of acute abdominal pain. An unspecific colitis was diagnosed. Blood counts showed a mild neutrophilic leukocytosis (12.6 Gpt/l) with a severe relative eosinophilia (30%), thrombocytopenia (67 Gpt/l), and an increased C-reactive protein (CRP 122 mg/l). The patient also had a deep venous thrombosis of the left leg. An explorative laparotomy was performed because of a strong suspicion of a presacral abscess. Pulmonary embolism and embolic pneumonia developed after surgery. A macular-cockade exanthema on the trunk and extremities was found. Histological examination revealed perivascular eosinophilic infiltrates. Histological and cytological analysis of bone marrow showed many eosinophilic granulocytes and a hypercellular medulla without increased numbers of blasts. No parasites in the blood and stools were found, and there was no evidence of neoplasm or cardiac involvement. p- and c-ANCAs (antineutrophil cytoplasmic antibodies), ANAs (antinuclear antibodies), and antibody against dsDNA were negative. Further genetic, FISH (fluorescence in situ hybridization), and PCR (polymerase chain reaction) analyses showed no evidence for chromosomal aberrations. An undefined hypereosinophilic syndrome with multiple organ involvement was diagnosed. Shortly after starting an oral prednisolone therapy (1 mg/kg body weight), the eosinophilia normalized. This therapy was stopped after 2 months and the patient is now, 6 months after diagnosis, in normal health.

CONCLUSION: As demonstrated in this case, eosinophilia requires a broad differential diagnosis. A hypereosinophilic syndrome can involve many organs and mimic other diseases. The new classification of the hypereosinophilic syndrome from 2006, based on pathophysiological insights, may foster better diagnosis and therapy for this rare disease.