With the widespread use of computed tomography (CT), subsolid nodules are more frequently encountered in daily practice. We present the case of a 74-year-old man with a large persistent well-defined subsolid nodule on CT. Although the lesion had a predominant ground-glass appearance on CT, 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) showed moderate FDG uptake. Lobectomy was performed and histopathologic examination showed an extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue. Teaching Point: When large persistent subsolid nodule with a predominant ground-glass aspect shows moderate uptake on 18F-FDG-PET, other possible diagnoses than adenocarcinoma should be kept in mind, including primary pulmonary lymphoma.