Multiple synchronous primary intra-abdominal neoplasms.

Multiple synchronous primary intra-abdominal neoplasms involving more than one organ system are rare, particularly if the appendix is involved. We report a patient with synchronous primary lesions in the colon, appendix, and the kidney. We also discuss the incidence of this entity with respect to sex and age, the organs most often involved in instances of multiple primary lesions, and review the criteria for differentiation of synchronous versus metachronous lesions.