(4) The term "cancer" when modified by an adjective or adjectival phrase
indicating a morphological type should be coded in the same manner as "carcinoma"
with that adjective or phrase. Thus, "squamous cell cancer" should be coded in the
same manner as "squamous-cell carcinoma."
b. Morphology codes (Volume 1, pages 1055 -1076).
(1) ICD-9-CM provides an optional set of four -digit codes preceded by the letter
"M" for identifying the morphology of neoplasms. An additional set of single digits is
provided to identify the behavior of the neoplasm, such as "/3" for malignant, primary
site. Morphology codes are not used in the inpatient record.
(2) The morphology codes may be located in the Alphabetical Index (Volume 2)
in alphabetical sequence under the main term entry for the specific neoplasm.
(3) The word morphology is defined as the study of the form and structure of
the cells and tissues from which the neoplasms arise.
(a) The properties of a particular neoplasm is determined by the tissue of
origin as opposed to the organ of origin.
(b) The type of cells that a malignant neoplasm is comprised of often
determines the rate of growth, degree of malignancy, and the particular type of
(4) Metastatic neoplasms are identified at the metastatic site by their
morphology, which is different from that of the normal tissue at the metastatic site and
the same as the morphology of the tissue and cells at the primary site. This is important
to remember when coding neoplasms and determining primary versus secondary sites.
(a) Classification of neoplasms by the tissue from which they arise are:
1. Epithelial tissue--adenoma, papilloma, carcinoma, and
2. Connective tissue--fibroma, leiomyoma, fibrosarcoma, and
3. Nervous tissue--meningioma and glioma.
(b) Classifications of neoplasms by cells from which they arise are:
1. Clear cell adenoma.
2. Acinar cell adenoma.
3. Basal cell carcinoma.
4. Squamous cell carcinoma.