DIFFERENTIAL DIAGNOSIS, INVESTIGATION AND TREATMENT
Pneumo-allergen specific IgE assay was normal, and the parasitological examination of the stools was sterile. The thoracic-abdominal-pelvic scan showed some emphysema lesions and a hepatic angioma. The patient received two trial antiparasitic treatments with Stromectol* (Ivermectin) but persistent hypereosinophilia was observed at 5060/mm3 (June 2015). In September 2015, he was referred to hematology for a specialized consultation. He then presented with pruritic urticarial skin lesions, evolving by flush associated with known dry cough and dyspnea. He did not present any alteration of performans status nor fever, no digestive disorder, no sign of cardiac insufficiency, no neurological deficit, no joint pain. Apart the hypereosinophilia, the rest of the blood cell count was without abnormality. Liver and kidney function tests, HIV and HTLV1 viral serologies, LDH, serum protein electrophoresis were also normal. Troponin and BNP assays, in search of cardiac damage, were normal. The respiratory function test showed an obstructive ventilatory disorder. The thoracic and abdominal-pelvic scans showed no tumor formation, which was confirmed by the PET scan. A search for the FIP1L1-PDGFRA transcript was then performed and was positive. The BCR-ABL transcript was undetectable. The search for T clonality was negative. Bone marrow aspiration revealed a rich marrow with eosinophilic hyperplasia, the karyotype showed a loss of the Y and in FISH examination, an interstitial deletion in 4q12 was found, the equivalent of FIP1L1-PDGFRA rearrangement. Therefore the diagnosis of a FIP1L1-PDGFRA-positive HES with skin and lung involvement was done. Treatment with Imatinib was started in October 2015 at a dose of 100mg/day with regular biological and clinical monitoring every 3 months.