14.3 Solid Tumor Rules for Head & Neck, Kidney, Urinary, CNS, Melanoma & Other Sites
Key Takeaways
Timing intervals for a new primary differ by module: head and neck more than 5 years, kidney and urinary more than 3 years, Other Sites more than 1 year, and melanoma more than 60 days apart; the CNS modules have no disease-free timing rule.
Tumors on both sides of a paired site are multiple primaries in head and neck (M5), kidney (M5) and melanoma (different laterality, M4), but bilateral nephroblastomas, bilateral vestibular schwannomas and bilateral retinoblastoma are single primaries.
Multiple urothelial carcinomas of the bladder, and urothelial carcinomas in several urinary organs, are generally a single primary; micropapillary plus conventional urothelial carcinoma is two primaries (urinary M8).
A glioblastoma after a glial tumor is a new primary (malignant CNS M7), multiple cranial meningiomas are one primary (non-malignant CNS M10), and a malignant CNS tumor after a resected non-malignant tumor is a new primary (non-malignant CNS M6).
Other Sites: prostate acinar adenocarcinoma is always one primary (M3), Kaposi sarcoma and retinoblastoma are always one primary, and bilateral epithelial ovarian tumors within 60 days are a single primary (M9).
Timing at a glance
| Module | Disease-free interval for a new primary | Rule |
|---|---|---|
| Head and neck | More than 5 years | M6 |
| Kidney | More than 3 years | M6 |
| Renal pelvis, ureter, bladder, other urinary | More than 3 years | M10 |
| Cutaneous melanoma | Melanomas diagnosed more than 60 days apart | M7 |
| Other Sites | More than 1 year | M12 |
| Malignant and non-malignant CNS | No disease-free timing rule | – |
Remember that the rules are hierarchical: an earlier rule, such as a site-code or laterality rule, can decide a case before the timing rule is reached.
Head and neck (M1–M13)
- M3: multiple primaries for tumors in any two listed site pairs, for example the aortic body and carotid body, or two different subsites of the larynx (glottis, supraglottis, subglottis, laryngeal cartilage). The module lists other subsite pairs as well.
- M4: sites that differ at the 2nd or 3rd character, giving multiple primaries.
- M5: tumors on both the right and left side of a paired site, for example both parotid glands, giving multiple primaries.
- M6: a new tumor after more than 5 years disease-free, giving multiple primaries.
- M7/M8: different subtypes or different rows in the site tables, giving multiple primaries (timing irrelevant).
- M9–M11: in situ and invasive combinations. An invasive tumor more than 60 days after in situ is a new primary.
- M12: same site, same row, giving a single primary.
Kidney (M1–M13)
- M3: codes differ at the 2nd, 3rd or 4th character, giving multiple primaries.
- M4: bilateral nephroblastomas (Wilms tumors) are a single primary, whether diagnosed together or years apart.
- M5: tumors in both kidneys (other than nephroblastoma) are multiple primaries.
- M6: more than 3 years disease-free, giving a new primary.
- M7–M9: histology table rules. Synchronous tumors on the same row in the same kidney are a single primary (M8).
Renal pelvis, ureter, bladder and other urinary (M1–M18)
Urothelial carcinoma tends to be multifocal throughout the urinary tract, so several rules make it one primary:
- M3/M4: tumors in both renal pelves, or both ureters, with no other urinary site involved, are multiple primaries.
- M5: synchronous flat in situ urothelial carcinoma (8120/2) in the bladder and one or both ureters, with no other urinary organ involved, is a single primary (coded to bladder by default).
- M6: invasive more than 60 days after in situ is multiple primaries.
- M7: multiple occurrences of in situ (/2) urothelial carcinoma in the bladder, either flat (8120/2) or noninvasive papillary (8130/2), are a single primary, whatever the timing. Only one /2 urothelial bladder primary is abstracted in a patient's lifetime.
- M8: micropapillary urothelial carcinoma 8131/3 and conventional or papillary urothelial carcinoma (8120/3, 8130/3), in any urinary sites, are multiple primaries.
- M9: multiple invasive urothelial carcinomas of the bladder are a single primary.
- M10: more than 3 years disease-free, giving a new primary.
- M11: urothelial carcinomas in multiple urinary organs (except micropapillary) are a single primary.
Malignant CNS and peripheral nerves (M1–M14)
- M3/M4: a recurrence of an oligodendroglioma with new features, or a glioma NOS recurring with a more specific histology, is a single primary.
- M5: a single tumor first diagnosed as non-malignant and managed with active surveillance that becomes malignant is a single primary (the malignant).
- M6: a malignant /3 CNS tumor and a non-malignant /0 or /1 CNS tumor are multiple primaries.
- M7: a glial tumor followed by glioblastoma (9440) is multiple primaries.
- M8: separate brain tumors with the same histology (multicentric or multifocal, any lobe or side) are a single primary.
- M9: tumors in any brain lobe and another part of the CNS (for example, the spinal cord or cauda equina) are multiple primaries.
Non-malignant CNS (M1–M15)
- M4: a benign /0 tumor that transforms to borderline /1 is a single primary.
- M6: a malignant tumor after a resected non-malignant tumor, or when resection status is unknown, is multiple primaries. Compare M3, the active-surveillance case, which is a single primary.
- M7: bilateral vestibular schwannomas (9560/0) or bilateral optic gliomas/pilocytic astrocytomas (9421/1) are a single primary.
- M10: two or more meningiomas of the cranial meninges are a single primary, whatever the laterality.
- M11: same-histology brain tumors are a single primary.
Cutaneous melanoma (M1–M8, 2021+)
- M3: melanomas in sites that differ at the 2nd, 3rd or 4th character are multiple primaries. For example, skin of the trunk C445 and skin of the upper limb C446 are two primaries. This rule also applies to a melanoma of unknown primary plus a known cutaneous primary.
- M4: different laterality gives multiple primaries.
- M5: different subtypes, such as nodular and epithelioid cell melanoma, give multiple primaries.
- M6: synchronous tumors on the same row with the same site code are a single primary.
- M7: melanomas diagnosed more than 60 days apart are multiple primaries. This includes in situ after invasive, and invasive after in situ.
Other Sites (M1–M21, 2023+)
| Rule | Outcome |
|---|---|
| M3 | Prostate acinar adenocarcinoma is always a single primary |
| M4 | Small cell carcinoma of the prostate more than 1 year after acinar adenocarcinoma is multiple primaries |
| M5 / M6 | Retinoblastoma (unilateral or bilateral) and Kaposi sarcoma (any sites) are always a single primary |
| M7 | Papillary and follicular thyroid tumors diagnosed within 60 days are a single primary |
| M8 | Anaplastic thyroid carcinoma plus any other thyroid histology is multiple primaries |
| M9 | Bilateral epithelial ovarian tumors within 60 days are a single primary |
| M10 | Tumors on both sides of a site listed in Table 1 (paired sites) are multiple primaries |
| M11 | Adenocarcinoma in familial adenomatous polyposis is a single primary (small bowel and other sites in this module) |
| M12 | More than 1 year disease-free is a new primary |
| M13 / M14 | Site codes differ at the 2nd or 3rd character, giving multiple primaries. A 4th-character difference gives multiple primaries only for listed sites such as the anus and anal canal |
| M20 | Invasive more than 60 days after in situ is multiple primaries |
Histology rules: patterns that repeat across modules
- A tumor with in situ and invasive parts: code the invasive histology.
- NOS plus a subtype: code the subtype when it is documented under the priority rules. When a subtype is described only with an ambiguous term, the conditions in Section 13.3 apply.
- Combination tables: use a combination code only when the module's table lists it, for example breast duct and lobular carcinoma 8522.
- Many modules have a "last resort" rule. Before using it, confirm that no earlier rule applies.
A patient treated for papillary urothelial carcinoma of the bladder (8130/3) in 2024 has a new invasive urothelial carcinoma of the bladder in 2026 with no micropapillary component. Under the urinary Solid Tumor Rules, how many primaries are there?
Two, because more than one year has passed
Two, because papillary and non-papillary urothelial carcinoma are different rows
One, because multiple invasive urothelial carcinomas of the bladder are a single primary (rule M9), which comes before the three-year timing rule
One, but only if the physician calls the second tumor a recurrence
A patient has a grade 2 astrocytoma resected in 2023 and is diagnosed with glioblastoma in 2026. What do the malignant CNS rules require?
Multiple primaries, because rule M7 abstracts multiple primaries when a glial tumor is followed by glioblastoma
A single primary, because the glioblastoma arose in the same location
A single primary, because the CNS rules have no timing rule
Multiple primaries only if more than three years have passed
Invasive melanomas are diagnosed on the skin of the back (C445) in January 2026 and the skin of the left arm (C446) in February 2026. How many primaries are abstracted?
One, because they were diagnosed within 60 days
Two, because the site codes differ at the fourth character (melanoma rule M3)
One, because both are cutaneous melanoma with the same histology
Two, but only because the diagnoses were more than 30 days apart
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