Format of ICD-O Topography Terms in the Numerical List

Each topographic term appears only once in the numerical list, as the examples in Table 1 demonstrate. The first listed term, printed in bold type under a particular code, is the preferred term.

In this example, "parotid gland" would describe all cases coded to C07.9. The bold type indicates that this is the preferred (first) term. The synonym, "parotid, NOS," is indented under "Parotid gland." The non-indented terms, "Stensen duct" and "parotid gland duct," are called equivalent terms. They are not synonyms of the preferred term (parotid gland) but are listed under the same code number because they are topographic subdivisions of the term listed first and are not sufficiently different to have their own codes. In the alphabetic index all these terms are given the code C07.9.

Table 1: Topography Term in Numerical list
Code Term
C07.9 Parotid Gland Bold type indicates that this is the preferred (first) term
        _____Parotid, NOS Synonym for "Parotid gland"
  Stenson Duct Non-indented terms are equivalent terms. They are not synonyms of the preferred term (parotid gland) but are listed under the same code number
        _____Parotid Gland Duct

Updated: December 13, 2023