No peripheral eosinophilia was documented. Open in a separate window Figure?2 S107 Radiological findings in patient number 2 2. cell carcinoma of the head and neck. 2 Cetuximab-associated pulmonary toxicity has been rarely described in the literature.3 4 Here, we report RGS17 on two patients who acquired an interstitial pneumonia most likely caused by cetuximab, since these patients did not improve despite the initiation of antimicrobial treatment. Case presentation Case 1 A 61-year-old Caucasian man was admitted to our hospital with dyphagia resulting in a weight loss of 5?kg undergoing treatment for a cT4b cN2c mesopharynx carcinoma diagnosed 2?months ago. Induction chemotherapy with three cycles of docetaxel, cisplatin and 5-fluorouracil was administered. As a complication of this treatment, the patient developed febrile neutropenia without a septic focus and was empirically treated with cefepime. After partial remission, intensity-modulated radiation therapy was S107 administered to the primary tumour including lymph nodes to a total dose of 70?Gy given in daily 2-Gy fractions combined with cetuximab (total six cycles, loading dose 600?mg, then 400?mg). On admission, the patient had no fever and physical examination revealed an acne-like skin rash of the neck which is a common side effect of cetuximab. Laboratory tests showed an elevated C-reactive protein of 106?mg/l. White blood cell count was normal with 3560/l. No chest x-ray was performed in the absence of pulmonary symptoms. Gastroscopy showed an erosive bulbitis which was interpreted along with the mucositis within the radiation field, as an additional cause of the dysphagia. The patient was commenced on amoxicillin/clavulanic acid on the assumption of a superinfection within the mesopharynx and on a proton pump inhibitor to treat the erosive bulbitis. In addition, a percutaneous endoscopic gastrostomy (PEG) was placed. A few days later, the patient developed pain in the upper abdomen and the PEG insertion site was slightly erythematous, suggestive of a PEG site infection. A superficial swab revealed growth of (with AmpC expression). Therefore, antimicrobial treatment was switched to ertapenem. Owing to increased infective parameter (C-reactive protein of 165?mg/l), the infectious diseases service was consulted regarding further diagnostic steps and treatment. Patient 2 The second patient, a 65-year-old Caucasian man, was also admitted to our hospital for commencement of PEG or nasogastric feeding for management of dyphagia. He suffered from both tonsillar squamous cell carcinoma and oesophageal adenocarcinoma. For the former, radiotherapy was administered starting S107 4?weeks before admission in combination with cetuximab 2?weeks after starting radiotherapy. Carboplatin and taxol were added for treatment of the oesopophageal carcinoma. Four days after stopping cetuximab and carboplatin, the patient developed fever with left renal pain. Physical examination revealed no pathological findings except for dermatitis of the neck which was interpreted as cetuximab-associated skin toxicity. Empiric antibiotic treatment with ceftriaxone was started, assuming a nosocomial pyelonephritis. The infectious diseases service was consulted for advice regarding further management. Investigations and treatment Patient 1 Owing to persistent subfebrile temperatures and previous abdominal pain, nosocomial urinary tract infection or catheter-related blood stream infections were excluded by repeated blood and urine cultures. No ascites or signs of cholecystitis were observed in ultrasound and CT of the abdomen. A subsequent CT of the lung showed ground-glass consolidation in the upper lobe and a small area of consolidation S107 in the inferior lobe of the right lung. Owing to immunosuppression, and serovar type 1 was excluded by induced sputum (Immunofluorescence stain, Kinyoun stain) and by urinary antigen, respectively. A repeat CT due to persistent fever and development of oxygen desaturation 3?days later showed a massive pleura effusion and a large consolidation with air bronchograms in the upper and lower lobe of the right lung (figure 1A). The pleural effusion was punctured and antibiotic treatment was changed from ertapenem to meropenem. The pleural fluid showed only 610 cells with 55% neutrophils, 7.5% lymphocytes and 22% of monocytes. Microbiology testing was.