Eur Respir J 2006; 27: 230–232 DOI: 10.1183/09031936.06.00089405 CopyrightßERS Journals Ltd 2006 CASE STUDY Cough and hypereosinophilia due to FIP1L1-PDGFRA fusion gene with tyrosine kinase activity K.F. Chung*, M. Hew*, J. Score#, A.V. Jones#, A. Reiter", N.C.P. Cross# and B.J. Bain+ ABSTRACT: Eosinophil-associated conditions, such as asthma and eosinophilic bronchitis, have AFFILIATIONS been associated with chronic persistent cough, usually responding to corticosteroid therapy. *National Heart and Lung Institute, Imperial College and Royal Brompton This case study reports a case of persistent cough associated with gastro-oesophageal reflux Hospital, (GOR) and hypereosinophilia. Treatment of GOR with proton pump inhibitors and fundoplication +St Mary’s Hospital Campus of did not control the cough. However, high dose prednisolone, but not inhaled corticosteroids, did. Imperial College, London, and, # The presence of the FIP1L1-PDGFRA fusion gene in myeloid cells was confirmed by fluo- Wessex Regional Genetics Laboratory, Salisbury District rescence in situ hybridisation analysis using CHIC2 deletion as a surrogate marker. The cough and Hospital, Salisbury, UK. other disease features were subsequently suppressed by the tyrosine kinase inhibitor, imatinib. "III Medizinische Universita¨tsklinik, This is the first case of persistent cough caused by hypereosinophilic syndrome characterised Fakulta¨tfu¨r Klinische Medizin by FIP1L1-PDGFRA fusion gene and aberrant tyrosine kinase activity. Mannheim der Universita¨t Heidelberg, Heidelberg, Germany. KEYWORDS: Cough, fusion gene, hypereosinophilic syndrome, imatinib, tyrosine kinase CORRESPONDENCE K.F. Chung National Heart and Lung Institute Dovehouse Street hronic cough is a common clinical pro- However, his eosinophil count was 1.76109?L-1. London SW3 6LY blem [1, 2]. Asthma, post-nasal drip or He was treated with inhaled corticosteroids for UK C rhino-sinusitis, and gastro-oesophageal 3 months and a week’s course of prednisolone Fax: 44 2073518126 reflux are the most common causes of chronic without benefit. He complained of regular epi- E-mail: [email protected] cough [3], but in many patients, no cause can be sodes of gastro-oesophageal reflux and a 24-h Received: identified despite thorough investigations and recording of oesophageal pH showed significant August 02 2005 empirical treatment [4, 5]. Conditions associated reflux of gastric acid. Treatment with proton Accepted after revision: with eosinophils in the airways, such as asthma pump inhibitors for up to 6 weeks and a Nissen October 13 2005 and eosinophilic bronchitis, have been associated fundoplication did not resolve his cough, with chronic cough and treatment with cortico- although his symptoms of reflux disappeared steroids, which suppress eosinophils, is usually after surgery. effective in controlling such cough. This study describes a patient with persistent cough In 2003, he was referred to the Royal Brompton associated with FIP1L1-PDGFRA positive hyper- Hospital because of intractable cough, which eosinophilia, a condition that has been described prevented him from working. He was producing recently [6]. This cough was controlled by high- a small amount of clear sputum. He also dose oral corticosteroid therapy and also by a complained of diarrhoea and night sweats, and specific inhibitor of this acquired, constitutively had lost 15 kg in weight in the preceding 2 yrs. active tyrosine kinase, imatinib. He had stopped smoking 15 yrs previously with a 15 pack-yr history. Clinical examination was CASE REPORT normal. Blood eosinophil count was 5.06109?L-1 A previously well 54-yr-old male scientist, an and immunoglobulin E was 61 IU?mL-1 (normal expert in bomb disposal, developed a chronic range 3–150 IU?mL-1); no anti-neutrophil cyto- cough in 2001. He was investigated using plasmic antibodies were detected. Computed spirometry, computed tomograms of the lungs tomography of the lungs showed thickening of and an endobronchial biopsy; all were normal. intrapulmonary airways with distal airway plug- European Respiratory Journal ging. Forced expiratory volume in one second, Print ISSN 0903-1936 For editorial comments see page 1. lung volumes and carbon monoxide gas transfer Online ISSN 1399-3003 230 VOLUME 27 NUMBER 1 EUROPEAN RESPIRATORY JOURNAL K.F. CHUNG ET AL. COUGH AND HYPEREOSINOPHILIA were normal, but he had a sensitive cough response to inhaled of PDGFRA gene further downstream than reported pre- capsaicin. Endobronchial biopsy showed goblet cell hyperpla- viously (fig. 2). The position of this previously undescribed sia and eosinophilic stromal inflammation. Bronchoalveolar breakpoint probably explains the difficulty in detection of the lavage fluid contained 25% eosinophils. Because of his fusion gene mRNA using standard PCR primers. extensive travels in tropical countries, stool examination and Following demonstration of the FIP1L1-PDGFRA fusion gene serological investigations were carried out and excluded 10 months after starting prednisolone therapy, the tyrosine parasitic infestations. A course of ivermectin had no effect on kinase inhibitor imatinib (100 mg?day-1) was commenced, with his cough or eosinophilia. Abdominal computed tomography a rapid disappearance of blood eosinophils. Prednisolone revealed hepatosplenomegaly with a 16-cm long spleen and a dosage was gradually discontinued after 2 months of imatinib craniocaudal liver span of 19 cm. therapy. The patient’s cough has not recurred and his Oral prednisolone (40 mg?day-1) was started and, within 2 diarrhoea has improved since commencing imatinib. No weeks, the cough and diarrhoea were controlled, but on steroid side-effects have been noted and the fusion gene is no longer tapering (a minimum daily dose of 20 mg was needed for detectable by specific RT-PCR designed for the breakpoints symptom control). Blood eosinophilia persisted at ,16109?L-1. present in this patient. Because of his persistent hypereosinophilia, he was referred for DISCUSSION further haematological investigations. Bone marrow aspirate This patient had evidence of severe gastro-oesophageal reflux and trephine biopsy showed increased numbers of eosinophils but his cough did not respond to treatment with proton pump and loosely clustered mast cells with no increase in blast cells inhibitors. A Nissen fundoplication that abolished reflux also or abnormal lymphoid infiltrate. There was no rearrangement failed to improve the patient’s cough, contrary to what has of TCRB or TCRG genes to suggest lymphocyte clonality. been previously reported in patients in whom a cough was Cytogenetic analysis was normal. Single-step RT-PCR for the evidently the result of reflux [7]. This therefore excluded the FIP1L1-PDGFRA fusion gene was negative, but nested PCR possibility of gastro-oesophageal reflux as underlying his was intermittently positive. Fluorescence in situ hybridisation cough. (FISH) analysis showed CHIC2 deletion, suggesting the The association of the persistent hypereosinophilia with the presence of this fusion gene, in 23% of interphase cells cough was next investigated. There was evidence of eosinophil (normal: f 10%) (fig. 1). The weak positive results with RT- inflammation in the airways mucosa, but the patient did not PCR and the low proportion of abnormal cells on FISH analysis have symptoms of asthma and his histamine bronchial led to further molecular investigation, which revealed a responsiveness was not abnormal. The level of hypereosino- breakpoint involving exon 16 of the FIP1L1 gene and exon 12 philia puts him into the category of idiopathic hypereosino- philic syndrome, but this diagnosis can now only be made after rigorously excluding all other causes of hypereosinophi- lia. Parasitic infestations, in view of his extensive travels to the tropics, were excluded. It was also unlikely that he represented a case of acute eosinophilic pneumonia, such as has been described in American servicemen serving in Iraq, attributed to exposure to desert sand or explosives [8]. Hypereosinophilic syndrome comprises a range of conditions, but recent developments have led to the identification of two distinct entities, in addition to residual idiopathic cases. First, a lymphocytic variant with hypereosinophilia secondary to a T- cell lymphoproliferative disorder demonstrated by the pre- sence of a circulating clonal T-cells has been described [9, 10]. This was excluded in this patient by the lack of rearrangement of the TCRB or TCRG genes. Secondly, a myeloproliferative disorder resulting from an interstitial deletion of the long arm of chromosome 4, leading to formation of a FIP1L1-PDGFRA fusion gene and synthesis of a protein with aberrant tyrosine b) FIP1L1 PDGFRA Centromere Telomere FIP1L1 PDGFRA RP11-119G9 exon 16 exon 12 RP11-317M11 RP11-232C18 FISH probes RP11-571I18 RP11-24O10 5CTTCCTGGTTCTGCTCCTTCt c t cAGATGGGAGTTTCCA3 L P G S A P S L R W E F P FIGURE 1. Fluorescence in situ hybridisation (FISH) analysis. a) Normal interphase with two overlapping red/green signals corresponding to two normal FIGURE 2. Molecular investigation of the FIP1L1-PDGFRA fusion in this case copies of chromosome 4. The metaphase spread on the right shows one normal study, showing the in-frame mRNA junction and predicted amino acid sequence. chromosome 4 and one CHIC2-deleted chromosome 4 (green signal only). b) The FIP1L1 sequence is shown in plain type, a four base pair insert of unknown c Scheme indicating the position of the genes and FISH probes. origin in lower case and PDGFRA in bold type.