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SEER Inquiry System - Report
Produced: 01/10/2025 12:19 PM
Question 20180087
Inquiry Details
References:
Solid Tumor Rules. Malignant CNS, 10/12/2018
Question:
Solid Tumor Rules (2018)/Multiple Primaries--Brain: How many primaries are there and what M Rule applies when two tumors identified in the brain are pathologically proven to be glioblastoma, IDH-wild type and anaplastic astrocytoma per the pathology report final diagnosis, but the diagnosis comment and tumor board indicates multifocal glioblastoma is favored? See Discussion.
Discussion:
The patient has one tumor each in the left parietal and left medial temporal lobe. The tumors were excised. The final diagnosis for the left parietal tumor is glioblastoma, IDH-wild type. he final diagnosis of the left medial temporal tumor is, at least anaplastic astrocytoma, WHO grade III; see comment. The comment states: There is a single focus of vascular hyperplasia, separate from neoplastic cells. No necrosis is identified. These findings on their own would warrant a diagnosis of anaplastic astrocytoma, WHO grade III. However, in the context of the patient's glioblastoma in the left parietal lobe, and imaging showing ring-enhancing lesions of the parietal and temporal lobes, this specimen is favored to be an un-sampled glioblastoma, WHO grade IV. The Solid Tumor Rules indicate we may no longer use terms like favor(s) to code the histology, leaving the final diagnosis as the priority source for coding histology per the Histology coding rules.
The tumor board review confirmed that, despite the anaplastic astrocytoma on pathology, they felt strongly that this is a multifocal glioblastoma and not an anaplastic astrocytoma. Both the pathologist's comment and the tumor board's assessment indicate this patient does not have two primaries. However, the Solid Tumor Rules do not give priority to the tumor board's assessment over the pathology, and registrars are not to use ambiguous terms to code histology thus leaving the two histologies to consider. Per the Solid Tumor Rules, one tumor that is glioblastoma and one tumor that is anaplastic astrocytoma are multiple primaries per M11 (Abstract multiple primaries when separate, non-contiguous tumors are on different rows in Table 3 in the Equivalent Terms and Definitions. Timing is irrelevant).
As a central registry, we cannot ask the pathologist or attending physician for clarification as suggested in Section 3 of the Malignant CNS and Peripheral Nerves Equivalent Terms and Definitions. We can only follow the current Solid Tumor Rules. In doing so, we would have to ignore both the pathologist's and tumor board's assessment that this patient has multifocal glioblastoma. Is there any concern that this will lead to over-reporting?
Answer:
Abstract separate primaries based on the two histology codes as these are separate tumors on different rows in Table 3 of the 2018 Solid Tumor Rules for Malignant CNS, Rule M11. The priority order for using documentation to identify histology for Malignant CNS is to use pathology/tissue from the resection over the tumor board.
