Abstract
BACKGROUND: Reports of synchronous multiple primary cancers in patients with oral cancer have recently been increasing because of progress in radiographic diagnostic techniques. Multiple primary cancers in patients with oral cavity cancer mainly occur in the head and neck region, lung, and esophagus. 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography is usually used to identify synchronous multiple primary cancers. CASE PRESENTATION: We herein describe a 69-year-old woman diagnosed with synchronous quadruple multiple primary cancers, namely a squamous cell carcinoma of the mobile tongue, invasive ductal carcinoma of the right breast, intraductal carcinoma of the left breast, and chromophobe renal cell carcinoma of the right kidney. We removed the four tumors over three surgical procedures to reduce the surgical risk because the patient had diabetes mellitus. To the best of our knowledge, this combination of multiple primary cancers has not been reported to date. Importantly, we followed this case for 5 years after surgery. The patient was alive and well with no clinical or radiologic signs of recurrent or metastatic disease at the time of this writing. CONCLUSIONS: In the present case, the kidney cancer could not be detected by 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography but could be detected by contrast-enhanced computed tomography. To avoid overlooking multiple primary cancers of the kidney, we suggest that contrast-enhanced computed tomography should cover a region extending to the inferior margin of the kidney, rather than only to the liver, in patients with oral cavity cancer.