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Rule D. If the site of origin
of the lymphoma is in the lymph nodes, code to C77._. If a
lymphoma involves multiple lymph node regions, code to C77.8
(lymph nodes of multiple regions). Code extranodal lymphomas
to the site of origin, which may not be the site of the biopsy.
If no site is indicated for a lymphoma and it is suspected
to be extranodal, code to C80.9 (unknown primary site).
Lymphomas are considered to be systemic (generalized) diseases
in contrast to solid tumors, such as breast or stomach cancer.
The majority of lymphomas arise in lymph nodes (topography
C27._) or lymphatic tissue, such as tonsils, spleen, Waldeyer
ring, Peyer
patches in the small intestine, or thymus;
these are all considered "nodal" lymphomas.
Lymphomas can also arise from lymphatic cells in organs,
for example stomach or intestine. Lymphomas occurring in specific
sites are called extranodal or extralymphatic. Lymphomas are
therefore not assigned a site-specific topography code. Although
the terms extranodal and extralymphatic are sometimes used
interchangeably, extranodal means that the the lymphoma does
not arise in a lymph node but may arise in one of the lymphatic
tissues mentioned above, while extralymphatic means the lymphoma
arises in a non-lymphatic organ or tissue.
When referring to nodal or extranodal lymphomas, it is important
to identify the primary site of the tumor, which may not be
the site of the biopsy or the site or spread of metastasis.
For example, diffuse large B-cell lymphoma can be either a
nodal or a primary extranodal tumor. The biopsy may be of
a lymph node, but the bulk of the primary disease may be in
a primary extranodal organ. Staging information from imaging
studies is the only reliable method of making this distinction
but may not be readily available to cancer registries. If
it is clear that a specific lymph node was the primary site,
this should be coded; if not, lymph node, NOS (C77.9) is appropriate.
If it appears that the primary site is not lymph nodes and
the site of origin is unknown, unknown primary site (C80.9)
is the appropriate code. This distinction is important because
extranodal lymphomas may have a better prognosis.
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