Multiple myeloma is a plasma cell dyscrasia characterized by neoplastic proliferation of plasma cells, producing a monoclonal immunoglobulin. Small lymphocytic lymphoma (SLL) is a neoplasm consisting of monoclonal B-cell lymphocyte proliferation. We present an extremely rare case of coexisting multiple myeloma, SLL, and squamous cell carcinoma of the lung in a 74-year-old female patient. She initially presented with a midline mass with pain in the lumbar area. Debulking surgery was performed, and pathology showed plasmacytoma. Further evaluation revealed coexistent IgG kappa myeloma. Imaging revealed extensive abdominal lymphadenopathy, and mesenteric lymph node biopsy confirmed the presence of SLL. The patient was also found to have a mass in the left lower lobe of the lung; biopsy showed squamous cell carcinoma. This patient was treated with lenalidomide and dexamethasone for multiple myeloma, and stereotactic body radiotherapy for limited stage lung cancer. Due to the more indolent course of SLL, watchful waiting was applied.