Primary site/Histology (Pre-2007)/Behavior: What is the correct site and histology/behavior for the following diagnosis: "mucinous cystadenoma of the appendix with perforation and pseudomyxoma peritonei." This was diagnosed at e-lap for a separate adenocarcinoma of the ascending colon.
For tumors diagnosed prior to 2007:
The appropriate code for mucinous cystadenoma of the appendix with perforation and pseudomyxoma peritonei is C18.1 8470/0. It is not reportable to SEER. According to our pathologist consultant, mucinous cystadenoma is a legitimate term for such appendiceal tumors. They may implant all over the peritoneum as pseudomyxoma peritonei, especially in the face of perforation, without being histologically malignant.
For tumors diagnosed 2007 or later, refer to the MP/H rules. If there are still questions about how this type of tumor should be coded, submit a new question to SINQ and include the difficulties you are encountering in applying the MP/H rules.
Reason for No Cancer-Directed Surgery: Could you explain why this field would be coded to 1 [Cancer-directed surgery was not recommended] or 2 [Contraindicated due to other conditions] for a case that presents with distant metastasis at diagnosis?
For cases diagnosed 1998-2002:
Code the Reason for No Cancer-Directed Surgery field to 1 [Cancer-directed surgery was not recommended] for patients who present with either a primary site or histology for which surgery is not a standard treatment. Also use code 1 for those patients who present with distant disease for a primary site that is typically treated surgically. Patients with distant metastasis typically do not have surgery performed as part of first course of treatment.
Code 2 [Contraindicated due to other conditions] is used when surgery would normally be recommended for the site (given the current stage of the tumor) but other medical conditions pose too much of a risk for the patient to undergo surgery.
MP/H Rules/Histology--Head and Neck: What is the histology code for salivary duct carcinoma of parotid gland?
Code salivary duct carcinoma to invasive ductal carcinoma (8500/3). Salivary duct carcinoma is an aggressive adenocarcinoma which resembles high-grade breast ductal carcinoma according to the WHO Classification of Tumors of Head & Neck.
EOD-Extension/EOD-Lymph Nodes--Rectosigmoid: How do you code these fields for a scan-based clinically staged T3 N1 rectosigmoid primary in a patient who received chemotherapy and radiation prior to a resection that demonstrated invasion only into the muscularis and no positive lymph nodes?
For cases diagnosed 1998-2003:
Use the best information available, in this case, the clinical staging, to code EOD. Code the EOD-Extension field to 40 [Invasion through muscularis propria or muscularis, NOS] and the EOD Lymph Node field to 3 [Regional lymph node(s) NOS] because the case had a clinical stage of T3 N1. EOD is coded using the most extensive clinical or pathologic stage.
EOD-Extension/EOD-Lymph Nodes--Cervix: How do you code these fields when the cancer extended to the pelvic wall and there are periaortic LN metastases?
For cases diagnosed 1998-2003:
Assign extension code 65 for contiguous (direct) extension of tumor from the cervix to the pelvic wall. Assign extension code 85 only if the pelvic wall is involved with discontinuous extension from the cervix; i.e., the cervical tumor spread indirectly (through lymph or vascular channels) to the pelvic wall. Code the pelvic wall involvement in the Extension field and the periaortic lymph node involvement in the Lymph Node field. When the computer does the algorithm, it will look at the periaortic lymph nodes and report the summary stage as distant and the TNM stage group as IV because periarotic nodes are M1. Do not code the periaortic lymph nodes in both fields. This is stage IV, distant disease, due to the periaortic lymph node involvement (EOD lymph nodes code 6).
Behavior--Breast: Is a breast biopsy diagnosis of "ductal carcinoma in situ with focal and very early stromal invasion" an invasive tumor with a behavior code 3?
Code the behavior to /3 [malignant, invasive].
"Stromal invasion" means the cancer is invasive. "Stroma" is the supporting connective tissue around and between ducts. It is outside the duct basement membrane. If the tumor cells extend into the stroma, the proper behavior designation for the tumor is invasive.
First course treatment--Heme & Lymphoid Neoplasms: How is a "donor lymphocyte infusion" that is used in the treatment of CLL coded?
Updated May 2026
Donor lymphocyte infusion (DLI) is coded as immunotherapy. The lymphocytes are donated by the same person who donated the original stem cell transplant. The lymphocyte infusion creates an immune response in which the T-cells are activated to attack the cancer cells.
EOD-Extension--Colon: How should this field be coded for "adenocarcinoma penetrating through bowel wall into adjacent adipose tissue?
For cases diagnosed 1998-2003: The difference between EOD-extension codes 40 and 45 is the level of the fat involved. Code 40 is subserosal fat immediately adjacent to the muscular wall of the colon inside the serosa/visceral peritoneum. Code 45 is pericolic fat in areas where there is a serosal surface or in the retroperitoneal areas of the ascending and descending colon where there is no serosa. Code 42 was added for use when it is not possible to determine whether subserosal fat or pericolic fat is involved. Code 42 should be used only when there is a reference to 'fat' (NOS) The answer for the case example above depends on the location of the primary and whether the fat referred to is within or outside the entire thickness of the colon wall. If no additional information is available, use code 42 [Fat, NOS].
Reportability/Histology--Colon: Is tubular adenoma with high grade dysplasia and focal invasion from a pathology report of a colon biopsy reportable?; if so, what is the histology code?
Tubular adenoma with high grade dysplasia and focal invasion is reportable. Assign the histology code and behavior as 8210/3 (Adenocarcinoma in tubular adenoma).
NAACCR Guidelines for ICD-O-3 Implementation discuss the term high grade dysplasia (without invasion). High grade dysplasia and related terms are under review and study for consideration as a reportable neoplasm. Registries should check with their state reporting legislation to see if included in the reporting requirements.
Reportability/Histology: Does Cancer Pathology Coding Histology And Registration Terminology (Cancer PathCHART) determine if the histology is reportable or do we have to use the Excel ICD-O-3.2 spreadsheet?
The CPC ICD-O-3 Site Morphology Validation Lists (SMVLs) designate all tumor site-morphology combinations that are either valid or impossible as determined for the sites reviewed by the Cancer PathCHART initiative. These lists provide information on the Validity Status of specific tumor site and morphology combinations, similar to the way the ICD-O-3 SEER Site/Histology Validation List used to. However, the CPC SMVLs do not include information on the reportability of specific tumor site and morphology combinations. For tumor reportability, you will continue to use the Excel ICD-O-3.2 spreadsheets posted to the NAACCR ICD-O-3 Coding Updates website: https://www.naaccr.org/icdo3/, and the most recent SEER Manual and federal, state, local, and other standard setters' reportability requirements.
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