Dirofilariasis is a common parasite infection in stray dogs caused by Dirofilaria immitis (dog heartworm). Under very rare circumstances, it can cause human pulmonary lesion via a vector/intermediate host, the mosquito. It typically presents as a well-circumscribed, peripheral, solitary pulmonary nodule on radiograph, and is easily confused with lung malignancy. Diagnosis rests on histopathologic identification of the excised worm. We reported a 48-year-old female with a rare coexistence of pulmonary dirofilariasis and lung cancer. Clinical suspicion of a mixed etiology should be maintained in a lung cancer patient with a separate lung nodule. An undetermined pulmonary nodule should not preclude the possibility of surgical intervention for lung cancer patients with resectable disease.