| D3A | Benign neuroendocrine tumors |
| D3A.0 | Benign carcinoid tumors |
| D3A.00 | Benign carcinoid tumor of unspecified site |
| D3A.01 | Benign carcinoid tumors of the small intestine |
| D3A.010 | Benign carcinoid tumor of the duodenum |
| D3A.011 | Benign carcinoid tumor of the jejunum |
| D3A.012 | Benign carcinoid tumor of the ileum |
| D3A.019 | Benign carcinoid tumor of the small intestine, unspecified portion |
| D3A.02 | Benign carcinoid tumors of the appendix, large intestine, and rectum |
| D3A.020 | Benign carcinoid tumor of the appendix |
| D3A.021 | Benign carcinoid tumor of the cecum |
| D3A.022 | Benign carcinoid tumor of the ascending colon |
| D3A.023 | Benign carcinoid tumor of the transverse colon |
| D3A.024 | Benign carcinoid tumor of the descending colon |
| D3A.025 | Benign carcinoid tumor of the sigmoid colon |
| D3A.026 | Benign carcinoid tumor of the rectum |
| D3A.029 | Benign carcinoid tumor of the large intestine, unspecified portion |
| D3A.09 | Benign carcinoid tumors of other sites |
| D3A.090 | Benign carcinoid tumor of the bronchus and lung |
| D3A.091 | Benign carcinoid tumor of the thymus |
| D3A.092 | Benign carcinoid tumor of the stomach |
| D3A.093 | Benign carcinoid tumor of the kidney |
| D3A.094 | Benign carcinoid tumor of the foregut NOS |
| D3A.095 | Benign carcinoid tumor of the midgut NOS |
| D3A.096 | Benign carcinoid tumor of the hindgut NOS |
| D3A.098 | Benign carcinoid tumors of other sites |
| D3A.8 | Other benign neuroendocrine tumors |