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Produced: 09/19/2025 12:02 AM
Question 20020062
Inquiry Details
References:
ICD-O-3, 34. Rule K
Question:
Discussion:
Can this same histology be used when you have two type B features in the thymoma specimen? What code is used to represent the histology?
Example 1: Thymoma, spindle cell and epithelial type
Example 2: Thymoma, mixed lymphocytic and epithelioid type
Answer:
For tumors diagnosed prior to 2007:
For example 1, code histology to 8582 [Thymoma, type AB]. This code is only applicable to "Type AB thymoma [mixed]" in the WHO classification. Use 8582 only for thymomas with type A and type B features. Spindle cell is a type A feature and epithelial is a type B3 feature.
For example 2, code histology to 8585 [Thymoma, type B3]. Lymphocytic is a B1 feature (8583) and epithelial is a B3 feature (8585). There is no type A component. Code the histology based on ICD-O-3 rule K on page 34.
For tumors diagnosed 2007 or later, refer to the MP/H rules. If there are still questions about how this type of tumor should be coded, submit a new question to SINQ and include the difficulties you are encountering in applying the MP/H rules.
