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For this case, assign code C670 [Trigone of bladder]. The description for this case states that the tumor location is the base of the bladder. Base is a synonym for trigone.

The interureteric ridge (or interureteric crest, or interureteric fold) is a fold of mucous membrane extending accross the bladder between the two ureteric orifices. The trigone is located below the interureteric ridge.

Default the coding of the Primary Site field for chordomas to the bone where the tumor began in the body if the primary site is not clearly stated to be soft tissue. Bone is often the primary site for chordomas.

Based on advice from pathologist consultants: This is one of those situations where we can be quite comfortable with a default, in this case to bone, not soft tissue. Chordoma is a tumor arising in the nucleus pulposis, presumably from remnants of notochord - thus its exclusive origin is in the sacrococcygeal region, spheno-occipital region, and vertebral bodies, otherwise known collectively as the axial skeleton. Any "chordoma" in soft tissue (with no relationship to axial skeleton) is probably a myxoid chondrosarcoma or parachordoma (extremely rare).

Code the primary site to main bronchus [C340].

Primary small cell carcinoma in the thymus/mediastinum is rare. A bronchial lesion with extension into the mediastinum is much more likely. In a case like this, it is difficult to be sure exactly where the tumor arose, however, it is recommended the default site be the main bronchus when there is no information to the contrary.

Updated May 2026

In the Abstractor Notes section in the Heme DB, it indicates the primary site may differ for LCH in the solitary disease and multisystem disease. This patient has multisystem disease with involvement of the bone, liver, spleen and retroperitoneum. The most common sites for multisystem involvement include three of the four above sites (bone, liver, and spleen).

Determine the primary site based on the knowledge of the usual sites of involvement for this disease, the actual sites of involvement for the case presented, and identifying which sites of involvement are likely metastatic and which are the potential primary sites. There are two potential primary sites of involvement: the bone and the retroperitoneum. Bone is a common site of involvement for LCH while the retroperitoneum is not. Code the primary site to C419 [bone, NOS] because multiple bones are involved for this patient and bone is the most common site for LCH based on the documentation in the Abstractor Notes.

The spleen and liver are typically not primary sites for this disease process. They become involved when there is multisystem involvement because they filter the blood. They are typically sites of metastatic involvement.

The Abstractor notes also indicate that if it's not possible to determine primary site for LCH, default to Bone, NOS (C419)

Because the site is specifically stated to "skin" of nipple [C44.5], this case is not reportable.

If possible, you may wish to confirm the type of biopsy performed. If the biopsy was done by FNA or needle biopsy, the biopsy tissue should contain a full-thickness of skin and subcutaneous breast (nipple) tissue. If that is the case, this tumor would likely be a reportable squamous cell carcinoma of nipple [C50.0]. If, however, this was a punch biopsy it is more likely a non-reportable squamous cell carcinoma of the skin [C44.5].

Code the Primary Site field to C809 [unknown] for this case. The thigh tumor is a metastatic site.

If there is no further information about where the cancer originated, assign C220. Use ICD-O-3 as the source for coding topography. The topography code associated with combined hepatocellular and cholangiocarcinoma (8180/3) is C220 when there is no other information available, according to ICD-O-3.

For cases diagnosed 2010 and forward, access the Hematopoietic Database at http://seer.cancer.gov/seertools/hemelymph.

Code primary site to C499 [blood vessels]. The definition in the Heme DB does specify that this type of extranodal large B-cell lymphoma is characterized by lymphoma cells within the lumina of blood vessels with the exception of larger arteries and veins. The reason no primary site is specified is that Western variant can originate in the skin or CNS.

SEER*Educate provides training on how to use the Heme Manual and DB. If you are unsure how to arrive at the answer in this SINQ question, refer to SEER*Educate to practice coding hematopoietic and lymphoid neoplasms. Review the step-by-step instructions provided for each case scenario to learn how to use the application and manual to arrive at the answer provided. https://educate.fhcrc.org/LandingPage.aspx.

The primary site is C482 [Peritoneum, NOS]. "Paracaval" means alongside or near the vena cava.

Code the site in which the primary tumor originated.

For cases diagnosed 1998-2003:

If only the extramedullary site is involved, such as colon, code the Primary Site field to the site of origin. Granulocytic or myeloid sarcoma is an exception to the rule that all leukemias should be coded to bone marrow as the primary site. Granulocytic sarcoma is a deposit of malignant myeloid cells in a site other than bone marrow (extramedullary). For EOD staging, granulocytic sarcoma [9930/3] is included in the Hematopoietic, Reticuloendothelial, Immunoproliferative and Myeloproliferative Neoplasms scheme and the Extension field is coded to 10 when the lymph nodes are negative, since it (like solitary plasmacytoma) is a localized deposit of tumor.

However, if the regional lymph nodes associated with the extramedullary primary site are involved, code the EOD-Extension field to 80 [Systemic disease] because the disease is no longer an isolated deposit of malignant granulocytes (in other words, it is not localized).

The EOD-Lymph Nodes field is coded to 9 regardless of whether or not the lymph nodes are involved because that is the only allowable code for that field.