Solid Tumor Rules/Multiple Primaries--Brain and CNS: How many primaries are accessioned when a 2005 diagnosis of glioblastoma multiforme is followed by a 2024 diagnosis of astrocytoma, IDH-mutant, WHO grade 4? See Discussion.
The patient underwent a gross total resection of the 2005 glioblastoma multiforme (9440/3). The patient was subsequently diagnosed with a 2024 diagnosis of astrocytoma, IDH-mutant, WHO grade 4 (9445/3).
Should Rule M13 apply to the new 2024 diagnosis and a new primary be accessioned because astrocytoma, IDH-mutant, WHO grade 4 is listed on a different row than glioblastoma? It is unclear whether histology 9445 should be classified as being on a different row because it is also listed as a subtype/variant for glioblastoma in Table 3. Table 3 lists histology 9445 as both “Astrocytoma, IDH-mutant, WHO grade 4” and as “Glioblastoma IDH-mutant.”
Abstract two primaries using the 2024 Malignant Central Nervous System (CNS) and Peripheral Nerves Solid Tumor Rules, Rule M13. Glioblastoma, IDH-wild-type (9440/3) and astrocytoma, IDH-mutant, grade 4 (9445/3) are on two separate rows in Table 3 of the Malignant CNS and Peripheral Nerves Solid Tumor Rules.
WHO Classification of Central Nervous System, 5th edition, lists the subtypes of glioblastoma, IDH-wild-type as giant cell glioblastoma; gliosarcoma; and epithelioid glioblastoma. The term glioblastoma multiforme is not recommended for glioblastoma, IDH-wildtype in the 5th edition, and lists astrocytoma, IDH-mutant, grade 4 as a subtype of astrocytoma, IDH-mutant.
2024 SEER Manual/Primary Site--Breast: Is Primary Site coded as C504 or C501 based on the Solid Tumor Rules and the SEER Manual Breast Coding Guidelines? The pathology report reads "Right Breast 10:00 1 cm from the nipple."
Codes C502-C505 take priority over code C501. The description for C501 in the Solid Tumor Rules has "Area extending 1 cm around areolar complex."
Assign Primary Site code C504 based on the location in the upper outer quadrant of the right breast, 10 o’clock, as opposed to code C501, around the areolar complex. The 2024 SEER Manual Breast Coding Guidelines advise that C502 - C505 are generally preferred over C501 when there is no other way to determine the subsite.