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SEER Inquiry System - Report
Produced: 01/07/2026 11:22 AM
Question 20190095
Inquiry Details
References:
#1: ICD-O-3
#2: 2018 SEER Manual, 7. 1.a.vii
Question:
Reportability/Histology--Thymus: Is a thymoma a malignancy if described as having separate tumor nodules within peri-thymic adipose tissue? See Discussion.
Discussion:
Patient had a thymectomy including pericardial fat for a mediastinal mass found incidentally during lung screening. Final diagnosis is WHO B3 thymoma. Staging Summary lists transcapsular invasion: "Present, as separate tumor nodules within peri-thymic adipose tissue." Tumor extension is stated to be "Confined to thymus, including peri-thymic adipose tissue." The pathologist staged this resection as pT1a pNX with no mention of mets. Clinically, there are no noted metastatic sites and no further treatment is planned.
Answer:
Report this case as a malignant thymoma. Our expert pathologist consultant reviewed this case and in his opinion, the "separate tumor nodules within peri-thymic adipose tissue" fit registry reporting criteria for separate tumor nodules making this a malignant thymoma.
