The table below gives the code numbers for neoplasms by anatomical site. For each site there are 6 possible code numbers according to whether the neoplasm in question is malignant, benign, in situ, of uncertain behavior, or of unspecified nature. The description of the neoplasm will often indicate which of the 6 columns is appropriate; e.g., malignant melanoma of skin, benign fibroadenoma of breast, carcinoma in situ of cervix uteri.
Codes listed with a dash -, following the code have a required additional character for laterality.
| Name | Malignant Primary | Malignant Secondary | Carcinoma in situ | Benign | Uncertain Behavior | Unspecified Behavior |
|---|---|---|---|---|---|---|
| retroperitoneal (space) (tissue) | C48.0 | C78.6 | - | D20.0 | D48.3 | D49.0 |
| retroperitoneum | C48.0 | C78.6 | - | D20.0 | D48.3 | D49.0 |
| retropharyngeal | C14.0 | C79.89 | D00.08 | D10.9 | D37.05 | D49.0 |
| retrovesical (septum) | C76.3 | C79.89 | D09.8 | D36.7 | D48.7 | D49.89 |
| rhinencephalon | C71.0 | C79.31 | - | D33.0 | D43.0 | D49.6 |
| rib | C41.3 | C79.51 | - | D16.7 | D48.0 | D49.2 |
| Rosenmuller's fossa | C11.2 | C79.89 | D00.08 | D10.6 | D37.05 | D49.0 |
| round ligament | C57.2 | C79.82 | - | D28.2 | D39.8 | D49.59 |
| sacrococcyx, sacrococcygeal | C41.4 | C79.51 | D16.8 | D48.0 | D49.2 | |
| – region | C76.3 | C79.89 | D09.8 | D36.7 | D48.7 | D49.89 |
| sacrouterine ligament | C57.3 | C79.82 | - | D28.2 | D39.8 | D49.59 |
Where such descriptors are not present, the remainder of the Index should be consulted where guidance is given to the appropriate column for each morphological (histological) variety listed; e.g., Mesonephroma - see Neoplasm, malignant; Embryoma - see also Neoplasm, uncertain behavior; Disease, Bowen's - see Neoplasm, skin, in situ. However, the guidance in the Index can be overridden if one of the descriptors mentioned above is present; e.g., malignant adenoma of colon is coded to C18.9 and not to D12.6 as the adjective "malignant" overrides the index entry "Adenoma - see also Neoplasm, benign."