The morphology code records the type of cell that has become
neoplastic and its biologic activity; in other words, it records
the kind of tumor that has developed and how it behaves. There
are three parts to a complete morphology code:
4 digits cell type (histology)
1 digit behavior
1 digit grade, differentiation or phenotype
In ICD-O morphology codes, a common root codes the cell type
of a given tumor, while an additional digit codes the behavior.
The grade, differentiation, or phenotype code provides supplementary
information about the tumor.
Cancer and Carcinoma
The words "cancer" and "carcinoma" are
often (incorrectly) used interchangeably, for example "squamous
cell cancer" is used for "squamous cell carcinoma."
To code the former as the latter would be reasonable. However,
"spindle cell cancer" could refer either to "spindle
cell sarcoma" or to "spindle cell carcinoma."
In ICD-O, the word "cancer" is listed only once,
as a synonym of the nonspecific term "malignant neoplasm,"
M-8000/3. Obviously, ICD-O cannot provide specific code numbers
for all the instances in which the word "cancer"
is used loosely and imprecisely as a part of a histologic
diagnosis.
Behavior
The behavior of a tumor is the way it acts within the body.
Pathologists use a variety of observations to determine the
behavior of a tumor. Table 18 shows the spectrum of behaviors.
A tumor can grow in place without the potential for spread
(/0, benign); it can be malignant but still growing in place
(/2, noninvasive or in situ); it can invade surrounding tissues
(/3, malignant, primary site); or even disseminate from its
point of origin and begin to grow at another site (/6, metastatic).
Table
18. 5th Digit Behavior Code for Neoplasms
|
Code
|
|
/0
|
Benign |
|
|
/1
|
Uncertain
whether benign or malignant |
|
Borderline
malignancy |
|
Low
malignant potential |
|
Uncertain
malignant potential |
|
|
/2
|
Carcinoma
in situ |
|
Intraepithelial |
|
Noninfiltrating |
|
Noninvasive |
/3
|
Malignant,
primary site |
|
|
/6*
|
Malignant,
metastatic site |
|
Malignant,
secondary site |
|
|
/9*
|
Malignant,
uncertain whether primary or metastatic site |
|
|
*
|
Not
used by cancer registries (used by some pathologists
in some parts of the world) |
|
|
Most cancer registries collect data only on malignant and
in situ neoplasms, that is, /3 or /2 of the behavior code.
Behavior codes /6, malignant, metastatic site, and /9, malignant,
uncertain whether primary or metastatic site, are not generally
used by cancer registries. For example, if a person has a
carcinoma that has spread to the lung and the site of origin
is unknown, the appropriate code is C80.9 (unknown primary
site) M-8010/3 (carcinoma). The /3 signifies the existence
of a malignant neoplasm of a primary site.
Carcinoma in situ and CIN III
Most cancer registries record carcinoma in situ arising at
any site. By far the largest number of in situ carcinomas
are diagnosed in the cervix uteri. In recent years, several
other closely related terms have been used by cytologists
and pathologists, notably intraepithelial neoplasia.
The term cervical introepithelial neoplasia, grade III (CIN
III), is often applied to the cervix. Unfortunately this description
includes both carcinoma in situ and severe dysplasia.
Leading experts in this field in several different countries
were consulted, and the majority felt that CIN III could be
considered as comparable to carcinoma in situ whether severe
dysplasia is mentioned or not. Severe dysplasia of the cervix
uteri without mention of CIN III is coded as for all other
sites of severe dysplasia according to SNOMED. Similar terms
in the vagina (VAIN III), vulva (VIN III), anus (AIN III),
and prostate (PIN III) should be treated in the same way.
Pathologists who do not believe that CIN III (unqualified)
is equivalent to in situ carcinoma can apply the matrix system
and change the behavior code to /1 (uncertain whether malignant
or benign).
The "Bethesda" cytology reporting system (23) recognizes
only two groups, low grade squamous intraepithelial lesion
and high grade squamous intraepithelial lesion; the high grade
group includes moderate dysplasia (CIN II), severe dysplasia,
and carcinoma in situ (CIN III).
Use of Behavior Code in Pathology Laboratories
While most of the instructions provided in this part of the
manual are aimed at coders and tumor or cancer registrars,
this section considers the classification needs of pathologists.
The primary difference between the two groups lies in the
use of the behavior code. Pathologists are usually interested
in "specimen coding" whereas the cancer registrar's
main interest is identification of the primary tumor. A pathologist
may receive several specimens from the same patient, for example
(a) a biopsy, (b) the resected primary site, and (c) a metastatic
site (Table 19). The pathologist wants to keep track of all
three of these specimens; the cancer registrar is only interested
in the primary. Each specimen would be coded with the appropriate
topography and morphology but in (b) the behavior would be
/6 (metastatic), indicating that the associated topography
code is not the site of origin. On the other hand, the cancer
registrar would report only (b) -- the primary site and morphology
with a behavior code/3.
Table
19. Examples of Specimen Coding in a Laboratory
|
|
Code
|
a. Biopsy diagnosis:
Supraclavicular lymph node, metastatic signet
ring cell adenocarcinoma, most likely from
stomach.
|
C77.0 8490/6
|
*b.
Primary site: Fundus of stomach, signet ring
cell ademonarcinoma |
C16.1 8490/3
|
c. Metastatic site:
Upper lobe bronchus, metastatic signet ring
cell adenocarcinoma.
|
C34.1 8490/6
|
|
|
* Codes for this case as
recorded in registry
|
|
|
|
|