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SEER Inquiry System - Report
Produced: 04/26/2025 7:04 AM
Question 20130190
Inquiry Details
References:
WHO Class Thymus Tumors, 164. 2004
Question:
Reportability: Is a thymoma, type B3 malignant and, therefore, reportable? See Discussion.
Discussion:
Recent information received from a registrar/pathologist states the WHO classifies well-differentiated thymic carcinoma [8585/3] as a synonym for type B3 thymoma.
Answer:
For cases diagnosed prior to 2021
Thymoma, type B3 [8585/1] is not reportable. Well-differentiated thymic carcinoma [8585/3] is reportable.
WHO lists well-differentiated thymic carcinoma as a synonym for type B3 thymoma, but indicates the behavior code differs as indicated above.
See the applicable SEER manual for cases diagnosed 2021 and later.
History:
Type B3 thymoma (8585/1) is not reportable. Well-differentiated thymic carcinoma (8585/3) is reportable.
WHO lists well-differentiated thymic carcinoma as a synonym for type B3 thymoma, but shows two different ICD-O-3 codes as indicated above.
