The appearance and distribution of pulmonary nodules can help narrow the differential diagnosis. Among infectious causes, typical bacterial pathogens can cause solitary nodular consolidations; septic emboli cause peripheral nodules (often with cavitation). Although invasive pulmonary aspergillosis commonly causes nodular pneumonia, those nodules are often surrounded by ground glass (halo sign) because of angioinvasion and parenchymal hemorrhage; in this case, the nodules had smooth borders without ground glass components, making aspergillus less likely. The radiographic appearance of the nodules, taken together with clinical signs, including the indolent course, absence of cough and dyspnea, progression despite antimicrobial regimen, and absence of neutropenia all supported a noninfectious etiology. Among malignant causes of pulmonary nodules, different radiographic patterns are possible. Primary lung cancer does not usually present as multiple, small pulmonary nodules; however, intrapulmonary metastases can. Renal cell carcinoma and medullary thyroid cancer can cause multiple, small nodules; however, the latter often have a micronodular, miliary pattern.