Multiple Myeloma (MM) is a malignant proliferation of the plasma cells mainly affecting bone marrow. Most common sites of extramedullary dissemination reported in the literature are skin, liver, kidneys and central nervous system. Multiple Myeloma is rarely associated with lung plasmacytoma. In fact; dissemination of MM in lung is relatively uncommon being described in only 5% of cases and therefore the diagnosis of this entity can be misleading to most clinicians. We report a rare case of lung plasmacytoma with MM in a 65-year-old, smoker, male who presented with shortness of breath and a heterogeneous mass involving the lower left lobe visualized on CT scan. Careful integration of the clinical manifestations with the radiological and pathological data from CT-guided transparietal lung biopsy and bone marrow biopsy led to the diagnosis of Multiple Myeloma with lung plasmacytoma. Given the rarity of this localization, the purpose of this study was to increase knowledge of this disease among pulmonologists, in order to provide more timely diagnosis.