It is a well-known epidemiological research issue that cancer patients are at high risk for developing multiple primary cancers. The risk increase is more likely among cancer survivors and elderly people. We present a case of synchronous cancers with pulmonary cancer and extramedullary plasmacytoma. A 68-year-old male patient was evaluated for back pain, walking difficulty, and urinary incontinence. MRI showed a vertebral mass lesion on T10‒11, with a pre-diagnosis of metastatic bone disorder. A PET-CT scan was performed to find out the primary cancer. This time, two mass lesions were striking: one on the right infrahilar region of the lungs and the other as a large lesion on the vertebras, as seen on MRI, which seemed to be two separate malignant lesions. Two biopsies were decided. The patient’s clinical picture deteriorated, and an urgent surgery for decompression and a diagnostic lung biopsy by bronchoscopy were performed. Histology of the vertebral lesion revealed kappa monotypic cell infiltration consistent with plasmacytoma, and histology of the lung revealed non-small cell lung carcinoma. He had a monoclonal gammopaty as IgG kappa with a level of 1.24 g/dL. Further investigation covered bone marrow, which confirmed the diagnosis of solitary plasmocytoma and primary lung carcinoma. Treatment was designed as radiotherapy for plasmocytoma and referral to the oncology unit with a recommendation for three monthly follow-ups for pursuing active myeloma development.

Multiple cancers comprise two or more primary cancers occurring in an individual originating in a primary site or tissue and are neither an extension nor a recurrence or metastasis. According to the timing of the cancers' diagnosis, the development of different cancers may be differentiated as synchronous or metachronous. The risk for the development of multiple primary cancers may be multifactorial as inherited predisposition to cancer; the lifestyle, cancerogen exposure related with environmental factors; previous cancer and increased survival and surveillance of cancer patients. We highlighted the need for comprehensive epidemiological data collection in cancer patients by publishing this case.