Cytologic features of inflammatory pseudotumor of the lung have not been described frequently. We report fine needle aspiration cytologic(FNAC) finding of a case of inflammatory pseudotumor misdiagnosed as adenocarcinoma in a 63-year-old man. The FNAC displayed a mixture of histiocytes, myofibroblasts, pneumocytes, and plasma cells. Some histiocytes and myofibroblasts had large nuclei with irregular nuclear membrane and prominent nucleoli, which mislead the diagnosis of adenocarcinoma on FNAC. The heterogeneous cell population is the unique cytologic features of inflammatory pseudotumor, which are helpful to distinguish it from other circumscribed benign and malignant lesions. Familiarity with these features is essential to avoid misdiagnosis and possible overtreatment.