Multiple Primaries (Pre-2007): Would osteosarcoma of the right arm diagnosed four years after malignant fibrous histiocytoma, also in the right arm, be a second primary when the physician states, "the patient's disease progressed to sarcoma after radiation was administered?"
For tumors diagnosed prior to 2007:
The osteosarcoma is a second primary. The first three digits of the histology codes are different: 8830 [Malignant fibrous histiocytoma] and 918_ or 919_ [Osteosarcoma]. In addition, the diagnoses are four years apart. According to SEER rules, these are separate primaries.
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.
Histology (Pre-2007)/Sarcoma: What code is used to represent the histology "Ewing's Sarcoma/Primitive Neuroectodermal Tumor (PNET)"? See Description.
A comment on one path report states "some authors consider both Ewing's & PNET to be the same biologic entity given that they share the same translocation between chromosomes 11 & 22." The pathologists at our children's hospital agree with this statement and contend that the two should have the same histologic code.
For tumors diagnosed prior to 2007:
Code histology as 9260/3, Ewing sarcoma. Ewing sarcoma is a specific histology on the continuum of primitive neuroectodermal tumors. Code Ewing sarcoma as it is more specific than PNET, NOS.
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.
EOD-Pathology Extension--Prostate: Is extracapsular extension implied by the phrase, "involvement of periurethral or urethral margins"? See Description.
The prostatectomy final pathology diagnosis states that the tumor involves the periurethral margin. The microscopic describes involvement of the urethral margin.
For cases diagnosed 1998-2003: Code the EOD-Extension field in the 20-34 range, which implies no extension beyond the prostate. Disregard involvement of periurethral margin or urethral margin, NOS, unless the pathologist or surgeon specifically mentions "extraprostatic urethra" involvement.
Date of Diagnosis/Histology (Pre-2007)/Behavior--Melanoma: How are these fields coded when the first shave biopsy finds "what appears to be the top of a melanoma" and a subsequent shave biopsy finds "features consistent with lentigo maligna?"
For tumors diagnosed prior to 2007:
Evaluate each case using all available information, including all pathology reports. Use the date of the first biopsy because it did identify the melanoma. The second biopsy confirmed the histologic type.
According to WHO's Histological Typing of Skin Tumors, lentigo maligna melanoma is similar to lentigo maligna, but has dermal invasion by atypical melanocytes.
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.
EOD-Extension--Thyroid: Is this field coded as involvement of the thyroid capsule if the thyroidectomy path specimen reveals papillary thyroid ca "tumor present within capsular blood vessels?"
For cases diagnosed 1998-2003: Tumor present within the blood vessels of the thyroid capsule is localized (extension code 30). The tumor has not penetrated the capsule itself if it is contained within the blood vessels.
Keep in mind that tumor size determines the extent of disease for thyroid extension codes 10, 20, 30 and 40.
EOD-Extension: How is this field coded for synchronous primaries when metastatic disease is found and there is no statement to indicate which primary is the source of the metastases? See Description.
Patient was diagnosed with both esophageal and pancreatic cancer. Liver metastases were also identified. The source of the liver mets is unknown.
For cases diagnosed 1998-2003: Search the record for information about the source of the metastasis. If no such information can be found, code the metastasis to both primaries. Update the abstracts when information becomes available confirming the primary site responsible for the metastasis. Assuming the liver metastases in the example above are distant (i.e. not contiguous) code extension as 85 [Metastasis].
First Course Treatment/Hormone Therapy--Thyroid: Is hormone replacement therapy such as levothyroxine (Synthroid) for thyroid carcinoma coded as first course of treatment? See Discussion.
Examples:
Patient was admitted for thyroidectomy with a diagnosis of probable thyroid cancer. Patient's history stated that patient received work-up for hypothyroidism and was found to have thyroid nodule. Fine needle aspirate suggested carcinoma. Patient's medications included Cytomel and Synthroid.
Patient was given levothyroxine after thyroidectomy for medullary thyroid carcinoma.
Updated December 2025
Do not code levothyroxine given to treat hypothyroidism or as cancer treatment for medullary carcinoma when given as replacement therapy and not as thyroid stimulating hormone (TSH) suppression therapy. Thyroid hormone therapy is generally coded as treatment for follicular, papillary, and oncocytic thyroid carcinomas.
Histology (Pre-2007)--Kidney: Is 8316/3 [Cyst associated renal cell carcinoma] the appropriate code for 1) Cystic renal cell carcinoma, 2) Renal cell carcinoma mass with cystic areas and 3) Cystic renal cell carcinoma, clear cell type?
For tumors diagnosed prior to 2007:
Yes, ICD-O-3 histology code 8316 is the correct code for the three examples above.
There are two categories of cyst-associated renal cell carcinomas: Renal cell carcinoma originating in a cyst, and Cystic renal cell carcinoma.
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.
Primary Site: Should we code C80.9 [unknown primary] or code C34.9 [Lung] according to the terminology, "most likely site of origin is lung"? See Description.
We have a case of metastatic keratinizing squamous cell ca. The work-up shows small densities in the lung that may represent inflammatory or chronic changes. No other imaging that shows origin. Physical exam states 2 months of left axillary mass. H/O SCCA of the skin involving chest wall.
Path reads: Metastatic w/d keratinizing SCCA. This lesion almost undoubtedly represents mets. The most likely site of origin is lung followed by esophageal primary or head & neck. The final discharge states, "Metastatic SCCA to Left Axilla".
Code the primary site according to the physicians' opinion, especially the treatment decision. If the physician treats the patient for a lung primary, code primary site as lung. If the primary site cannot be determined, code C80.9.
According to the pathologist, the most likely primary site for the example above is lung. The final discharge diagnosis does not reflect the pathologist's opinion, and does not contradict it either. If there is no conflicting medical opinion, code primary site to C34.9 [lung].
Surgery of Primary Site/Date Therapy Initiated--Head & Neck: Would a biopsy, NOS, that removed the majority of the tumor be used to code these fields? See Description.
Patient underwent biopsy, NOS, of a carcinoma of the tongue. Subsequent glossectomy revealed microscopic focus of residual squamous cell carcinoma.
If the biopsy NOS removed all macroscopic disease, code the date of the biopsy NOS as the date therapy initiated. If macroscopic disease remained following the biopsy NOS, code the glossectomy date as the date therapy initiated.
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