Other Differences

Special Codes in ICD-O for Topography of Lymph Nodes (C77) and Hematopoietic and Reticuloendothelial Systems (C42)

In ICD-10, the category C77 is used for secondary and unspecified malignant neoplasms of lymph nodes. In ICD-O, C77 is used as the topography code for lymph nodes. As a result, most of the malignant lymphomas (C81-C85) in ICD-10 are coded to the topography code C77 in ICD-O.

C42 is a vacant category in ICD-10 but is used in ICD-O to designate several topographic sites within the hematopoietic and reticuloendothelial systems. This category serves principally as the topography site for most of the leukemias and related conditions classified to C90-C95 in ICD-10. Figure 6 lists the subcategories for C42 in ICD-O.

Figure 6. ICD-O Topography Codes Not in ICD-10
C42 Hematopoietic and Reticuloendothelial System
C42.0 Blood
C42.1 Bone Marrow
C42.2 Spleen
C42.3 Reticuloendothelial system, NOS
C42.4 Hematopoietic system, NOS

For example chronic lymphocytic lymphoma is coded C91.1 in ICD-10. In ICD-O, it is coded C42.1 (the topography code for bone marrow), M-9823/3 (the morphology code for chronic lymphocytic leukemia).

The ICD-10 category for malignant neoplasm of the spleen (C26.1) does not appear under digestive organs in ICD-O, Third Edition. Following the practice of ICD-O, First Edition, the spleen is assigned code C42.2, under the hematopoietic and reticuloendothelial systems.

Hydatidiform Mole and Neurofibromatosis (Von Recklinghausen disease except bone)

The final differences between ICD-O and Chapter II of ICD-10 are that hydatidiform mole, NOS (C58.9 M-9100/0 in ICD-O) is classified not in Chapter II (Neoplasms) of ICD-10 but in Chapter XV "Pregnancy, Childbirth and the Puerperium" (Category O01.9, Hydatidiform mole), and neurofibromatosis including Von Recklinghausen disease except bone (M-9540/1 in ICD-O) appears in Chapter XVII "Congenital Malformations, Deformations and Chromosomal Abnormalities" as Category Q85.0.

HIV Disease and AIDS

There has been great interest in malignant neoplasms associated with human immunodeficiency virus (HIV) disease. These neoplasms should be coded following the rules in the ICD-O-3 manual. The associated condition, acquired immunodeficiency syndrome (AIDS), could be coded in a separate field of the cancer registry data file.

Functions of Neoplasms

ICD-O does not generally provide code numbers for the function of neoplasms, for example catecholamine production by a malignant pheochromocytoma (C74.1, M-8700/3). Separate codes, such as those in Chapter IV "Endocrine, Nutritional and Metabolic Diseases" of ICD-10, can be used to record some of the functions of neoplasm. Catecholamine production in the example above would be coded to E27.5.