A 44-year-old man, a nonsmoker, has experienced a 3-kg weight loss over the past 3 months. He recently developed a low-grade fever and cough with mucoid sputum production, and after 1 week, he noticed blood-streaked sputum. On physical examination, his temperature is 37.7deg C. There are bilateral crackles in the left upper lobe on auscultation of the chest. Chest CT scan shows a 3-cm left upper lobe nodule with decreased attenuation centrally. Laboratory studies show hemoglobin, 14.5 g/dL; platelet count, 211,400/ mm3; and WBC count, 9890/ mm3 with 40% segmented neutrophils, 2% bands, 40% lymphocytes, and 18% monocytes. Which of the following findings in his sputum sample is most likely to be present?