Gastric carcinoma and renal cell carcinoma as an atypical presentation of multiple primary malignancies: a case report and review of the literature.

Background: Gastric carcinoma (GC) with second primary malignancy (SPM) is the most frequent combination within the multiple primary malignancies (MPM) group. The presentation of a GC associated with a synchronized SPM in the kidney is extremely rare and unusual. This study presents a rare case of synchronous tumors, describes the main associated risk factors, and emphasizes the need to rule out SPM.