Stay alert for most appropriate code for 'overlapping sites.' If you have trouble distinguishing the cecum from the sigmoid colon or the duodenum from the descending colon, take a moment to review the graphic below. To see how anatomy can compare to your coding options, check the table, which offers a sampling of codes related to primary neoplasm diagnoses. Caution: For example, ICD-9 offers 151.8 (Malignant neoplasm of stomach; other specified sites of stomach) with the note: "Malignant neoplasm of contiguous or overlapping sites of stomach whose point of origin cannot be determined."