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4 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
Type A and type AB thymoma are the indolent end of thymoma, tumours of the thymus gland made of spindle-shaped epithelial cells (type A) or mixed with lymphocyte-rich areas (type AB), mostly in older adults and driven by a GTF2I mutation. Nine in ten are found at an early stage and almost none come back after complete surgery, so surgery alone is usually the whole treatment.
The WHO classification of thymic tumours divides thymoma into types A, AB, B1, B2 and B3 (with rare others), and the ITMIG consensus refined the criteria at the A/AB borderland and proposed the term atypical type A thymoma for tumours with increased mitoses or necrosis (Marx 2014). In the worldwide database, type A made up 12 percent and, with type AB, occurred at a higher age (64 and 57 years); 90 percent of type A were stage I or II, and recurrence after resection was 1 to 2 percent for types A and AB against 2 to 7 percent for B1 to B3 (Weis 2015). The GTF2I L424H mutation, characteristic of types A and AB, is recorded on the parent page. Atypical type A components can rarely metastasise, as in a case with lung and brain metastases 10 and 15 years after diagnosis (Journal of Thoracic Disease 2017).
How it differs from its parent: the parent page covers all thymoma types and their staging; types A and AB are the oldest patients, the earliest stages, the lowest recurrence and the GTF2I-mutant biology, and paraneoplastic myasthenia gravis is less frequent than with the B types.
| Setting | Approach | Guideline |
|---|---|---|
| All stages | Complete resection; postoperative radiotherapy for incomplete resection or stage III as on the parent page; systemic therapy rarely needed. | not mapped |