Meaning of "NOS" & How It Is Used

"NOS" is printed after topographic and morphologic terms that appear elsewhere in ICD-O with an additional modifying word or phrase. In the alphabetical index, "NOS" is listed, followed by the alphabetic listing of modifying words. Use the code for a term followed by "NOS" when:

  1. a topographic or morphologic term is not modified
  2. a topographic or morphologic term has an adjective that does not appear elsewhere
  3. a term is used in a general sense

For example, Figure 12 shows that in the alphabetic index "adenocarcinoma, NOS" is followed by a long list of adjectival descriptors, each with its specific code. If the diagnosis is adenocarcinoma, the correct code is M-8140/3 "adenocarcinoma, NOS."

Figure 12. Examples of NOS Code Placement
  Adenocarcinoma(See also Carcinoma)
M-8140/3 NOS
M-8140/6 NOS, metastatic
M-8280/3 acidophil
M-8550/3 acinar
M-8550/3 acinic cell
M-8370/3 adrenal cortical
M-8251/3 alveolar
M-8244/3 and carcinoid, combined
M-8560/3 and epidermoid carcinoma, mixed
M-8560/3 and squamous cell carcinoma, mixed
M-8402/3 apocrine
M-8147/3 basal cell
M-8300/3 basophil
M-8160/3 bile duct
M-8250/3 bronchilolar
M-8250/3 bronchiolo-alveolar
M-8420/3 ceruminous
M-8270/3 chromophobe and so forth

If a diagnostic phrase such as "atypical adenocarcinoma" is used, the code is also M-8140/3 because the adjective (atypical) does not appear in the list of terms modifying "adenocarcinoma." Thus, "NOS" is printed in both the numerical lists and the alphabetic index to indicate to the coder and to the decoder that other modifiers of the term are listed elsewhere.

In a few instances, "NOS" is also used to indicate that a particular term is used in a general sense. For example, "NOS" is printed after "endocrine gland" in "C75.9 endocrine gland, NOS" to indicate that other specific endocrine glands such as "pineal gland" and "pituitary gland" are also listed with their specific codes.