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Alphabetical Index

The alphabetical index is used to code topography (anatomical sites) and morphology (histological terms). The index also includes selected tumor-like lesions and conditions. Topography codes are identified by the letter C, the first character of codes in Chapter II ICD-10. The prefix M is used to identify morphology codes. The terms are listed under both the noun and the adjective. For example, basophil adeno-carcinoma is listed under B for "basophil" and under A for "adenocarcinoma, basophil."

Format and Use of Alphabetic Index

Figure 11 shows the first column of terms in the alphabetic index. Any word that appears as part of three or more terms is in bold type (such as "Abdomen," "Abdominal," and "Abdominal wall"), and the terms that include this word are indented under it. Topographic (C) and Morphologic terms (M) are not mixed under a single heading; there is always a vertical space before and after each group.

The first lead term is "Abdomen." Since there are more than three modifying terms, Abdomen is in bold type. The "NOS" term is always listed first under a heading in the index (rather than in alphabetic order under N).

A vertical space separates the "Abdomen" group and the next two terms containing the word "abdominal." Since there are only two morphologic terms beginning with "abdominal," they do not need a heading; however the following four topography terms do have a bold heading "Abdominal."

In the alphabetic index, a vertical space means:

  1. a change from topographic to morphologic term(s) or vice versa
  2. the end of a group

Tumor-like lesions and conditions

At the bottom of the column in Figure 11 , the alphabetic index also includes certain tumor-like lesions and conditions in their appropriate alphabetic order. These could be confused with neoplasms: for example, they end in "oma" or are premalignant conditions. No ICD-O morphology code is given after the M-, only seven dashes (M-------), because these conditions are not considered to be neoplasms.

Figure 11. First Column of Alphabetic Index
- A -

Abdomen
C76.2 NOS
C47.4 autonomic nervous system
C49.4 connective tissue
C49.4 muscle
C47.4 peripheral nerve
C44.5 skin
C49.4 subcutaneous tissue
M-8822/1 Abdominal desmoid
M-8822/1 Abdominal fibromatosis
Abdominal
C49.4 aorta
C15.2 esophagus
C77.2 lymph node
C49.4 vena cava
Abdominal wall
C76.2 NOS
C44.5 NOS (carcinoma, melanoma, nevus)
C49.4 NOS (sarcoma, lipoma)
C49.4 adipose tissue
C47.4 autonomic nervous system
C49.4 connective tissue
C49.4 fatty tissue
C49.4 fibrous tissue
C49.4 muscle
C47.4 peripheral nerve
C49.4 skeletal muscle
C44.5 skin
C49.4 soft tissue
C49.4 subcutaneous tissue
C72.5 Abducens nerve
M-9871/3 Abnormal marrow eosinophils, acute myeloid leukemia with (includes all variants)
M-9871/3 Abnormal marrow eosinophils, acute myelomonocytic leukemia with (includes all variants)
M-8075/3 Acantholytic squamous cell carcinoma
M------- Acanthoma, clear cell (see SNOMED)
M------- Acanthosis nigricans (see SNOMED)

Instead, there is a note in parentheses (see SNOMED) to refer the reader to the Systematized Nomenclature of Medicine (2,3)

In ICD-O-1 and ICD-O-2, a SNOMED code was provided. However, because at least two editions of SNOMED are in current use and the codes differ slightly for these non-neoplastic lesions and conditions, specific SNOMED codes were omitted from ICD-O, Third Edition.

Lymphoma and Leukemia Listings

Lymphomas and leukemias are exceptions to the rule of listing conditions under all parts of the terms. The number of permutations and combinations in leukemia and lymphoma terms is such that the index would have been too long. There is only one list for "lymphoma, malignant" and one for "leukemia."